JP6421273B1 - Apparatus, method and program for measuring normal incident acoustic characteristics - Google Patents

Abstract

A normal incident acoustic characteristic measuring apparatus and a normal incident acoustic characteristic measuring method capable of effectively measuring normal incident acoustic characteristics at a high temperature are provided. A normal incidence acoustic characteristic measuring apparatus includes a tube main body in which a sound source is disposed at one end and a test body to be measured is disposed in a tube, and the sound source and the test in a tube wall of the tube main body. A first sound pressure sensor having a first probe disposed at a first position between the body and the tube wall of the tube body between the sound source and the test body and the first A second sound pressure sensor having a second probe disposed at a second position closer to the specimen than the first position; a first temperature sensor for measuring a temperature of the first probe; A second temperature sensor for measuring a temperature of the second probe, a measured temperature of the first probe by the first temperature sensor, and a measured temperature of the second probe by the second temperature sensor, The temperature distribution of the first probe and the second probe As the degree distribution approaches, including a temperature adjustment unit for heating or cooling one or both of said first probe and said second probe. [Selection] Figure 1A

Description

  The present invention relates to an apparatus, a method, and a program for a normal incidence acoustic characteristic measuring apparatus.

  In Non-Patent Document 1, a transparent quartz tube is used as a standing wave tube, the transparent quartz tube on which the sample is arranged is heated to 400 ° C. in an annular electric furnace, and the sample is subjected to the standing wave ratio method. It is described that the normal incident sound absorption coefficient was measured.

The Acoustical Society of Japan, Vol. 40, No. 9, (1984) 612-619

  However, when measuring normal incidence acoustic characteristics at high temperatures, there are problems with conventional devices and methods.

  The present invention has been made in view of the above problems, and an object thereof is to provide an apparatus, a method, and a program capable of effectively measuring normal incidence acoustic characteristics at high temperatures.

  A normal incidence acoustic characteristic measuring apparatus according to a first aspect of an embodiment of the present invention for solving the above problem is a tube in which a sound source is arranged at one end and a test object to be measured is arranged in the tube. A first sound pressure sensor having a main body, a first probe disposed at a first position between the sound source and the test body of the tube wall of the tube body, and the tube wall of the tube body A second sound pressure sensor having a second probe disposed between the sound source and the test body and at a second position closer to the test body than the first position; A first temperature sensor that measures the temperature of the probe, a second temperature sensor that measures the temperature of the second probe, a measured temperature of the first probe by the first temperature sensor, and the second Based on the measured temperature of the second probe by the temperature sensor of the previous As the temperature distribution of the first probe and the temperature distribution of the second probe approaches, including a temperature adjustment unit for heating or cooling one or both of said first probe and said second probe. ADVANTAGE OF THE INVENTION According to this invention, the normal incidence acoustic characteristic measuring apparatus which can measure the normal incidence acoustic characteristic in high temperature effectively is provided.

  In order to solve the above problems, a normal incidence acoustic characteristic measurement method according to a first aspect of one embodiment of the present invention is a tube in which a sound source is disposed at one end and a test object to be measured is disposed in the tube. A first sound pressure sensor having a main body, a first probe disposed at a first position between the sound source and the test body of the tube wall of the tube body, and the tube wall of the tube body And a second sound pressure sensor having a second probe disposed between the sound source and the test body and at a second position closer to the test body than the first position. Preparing the first sound pressure sensor via the first probe and the second probe while radiating sound waves from the sound source toward the test body into the heated tube body And measuring the sound pressure in the tube by the second sound pressure sensor, During the measurement of the sound pressure by the first sound pressure sensor and the second sound pressure sensor, the temperature of the first probe and the second probe is measured, and the first probe and the second probe are measured. Or heating one or both of the first probe and the second probe so that the temperature distribution of the first probe and the temperature distribution of the second probe approach Cooling, and the sound pressure measured by the first sound pressure sensor and the second sound pressure sensor via the first probe and the second probe, one or both of which are heated or cooled. Based on evaluating normal incidence acoustic properties of the specimen. According to the present invention, there is provided a normal incidence acoustic characteristic measurement method capable of effectively measuring normal incidence acoustic characteristics at high temperatures.

  A normal incidence acoustic characteristic measuring apparatus according to a second aspect of an embodiment of the present invention for solving the above-described problem is a tube in which a sound source is disposed at one end and a test object to be measured is disposed in the tube. A first sound pressure sensor having a main body, a first probe disposed at a first position between the sound source and the test body of the tube wall of the tube body, and the tube wall of the tube body A second sound pressure sensor having a second probe disposed between the sound source and the test body and at a second position closer to the test body than the first position; By circulating a heat exchangeable fluid around the probe and the second probe and / or by connecting the first probe and the second probe with a heat conductive member, Temperature distribution of the first probe and temperature distribution of the second probe Including, and soaking unit to bring the. ADVANTAGE OF THE INVENTION According to this invention, the normal incidence acoustic characteristic measuring apparatus which can measure the normal incidence acoustic characteristic in high temperature effectively is provided.

  The normal incidence acoustic characteristic measuring method according to the second aspect of one embodiment of the present invention for solving the above-mentioned problem is a tube in which a sound source is disposed at one end and a test object to be measured is disposed in the tube. A first sound pressure sensor having a main body, a first probe disposed at a first position between the sound source and the test body of the tube wall of the tube body, and the tube wall of the tube body And a second sound pressure sensor having a second probe disposed between the sound source and the test body and at a second position closer to the test body than the first position. Preparing the first sound pressure sensor via the first probe and the second probe while radiating sound waves from the sound source toward the test body into the heated tube body And measuring the sound pressure in the tube by the second sound pressure sensor, Circulating heat exchangeable fluid around the first probe and the second probe during measurement of the sound pressure by the first sound pressure sensor and the second sound pressure sensor, and / or Alternatively, by connecting the first probe and the second probe with a heat conductive member, the temperature distribution of the first probe and the temperature distribution of the second probe are brought close to each other, and the periphery thereof. And / or by the first sound pressure sensor and the second sound pressure sensor via the first probe and the second probe connected by the heat conductive member. Evaluating normal incidence acoustic characteristics of the specimen based on measured sound pressure. According to the present invention, there is provided a normal incidence acoustic characteristic measurement method capable of effectively measuring normal incidence acoustic characteristics at high temperatures.

  A normal incidence acoustic characteristic measuring apparatus according to a third aspect of an embodiment of the present invention for solving the above-described problem is a tube in which a sound source is disposed at one end and a test object to be measured is disposed in the tube. A first sound pressure sensor having a main body, a first probe disposed at a first position between the sound source and the test body of the tube wall of the tube body, and the tube wall of the tube body A second sound pressure sensor having a second probe disposed between the sound source and the test body and at a second position closer to the test body than the first position; A first temperature sensor for measuring the temperature of the first probe, a second temperature sensor for measuring the temperature of the second probe, and a first sound pressure sensor via the first sound pressure sensor via the first probe. Measurement sound pressure, second by the second sound pressure sensor via the second probe Correction transfer function calculation for calculating a correction transfer function based on constant sound pressure, measured temperature of the first probe by the first temperature sensor, and measured temperature of the second probe by the second temperature sensor Part. ADVANTAGE OF THE INVENTION According to this invention, the normal incidence acoustic characteristic measuring apparatus which can measure the normal incidence acoustic characteristic in high temperature effectively is provided.

  In order to solve the above problems, a normal incidence acoustic characteristic measurement method according to a third aspect of one embodiment of the present invention is a tube in which a sound source is disposed at one end and a test object to be measured is disposed in the tube. A first sound pressure sensor having a main body, a first probe disposed at a first position between the sound source and the test body of the tube wall of the tube body, and the tube wall of the tube body And a second sound pressure sensor having a second probe disposed between the sound source and the test body and at a second position closer to the test body than the first position. Preparing the first sound pressure sensor via the first probe and the second probe while radiating sound waves from the sound source toward the test body into the heated tube body And measuring the sound pressure in the tube by the second sound pressure sensor, During the measurement of the sound pressure, measuring the temperature of the first probe and the temperature of the second probe, a first measured sound pressure by the first sound pressure sensor via the first probe, A correction transfer function is calculated based on the second measured sound pressure by the second sound pressure sensor via the second probe, the measured temperature of the first probe, and the measured temperature of the second probe. And evaluating normal incidence acoustic characteristics of the specimen based on the corrected transfer function. According to the present invention, there is provided a normal incidence acoustic characteristic measurement method capable of effectively measuring normal incidence acoustic characteristics at high temperatures.

  In the normal incidence acoustic characteristic measurement program according to the third aspect of the embodiment of the present invention for solving the above-described problem, a sound source is arranged at one end, and a test object to be measured is arranged in a tube. A tube main body, a first sound pressure sensor having a first probe disposed at a first position between the sound source and the test body among the tube walls of the tube main body, and the tube wall of the tube main body A second sound pressure sensor having a second probe disposed between the sound source and the test body and located at a second position closer to the test body than the first position. A program used for measuring normal incident acoustic characteristics using an apparatus, wherein the first measured sound pressure by the first sound pressure sensor via the first probe, and the second probe via the second probe Second sound pressure measured by a second sound pressure sensor, the first probe Measurement temperature, and a program for causing a computer to function as a correction transfer function calculating means for calculating a correction transfer function based on the measured temperature, the second probe. According to the present invention, there is provided a normal incidence acoustic characteristic measurement program capable of effectively measuring normal incidence acoustic characteristics at high temperatures.

  According to the present invention, an apparatus, a method, and a program capable of effectively measuring normal incidence acoustic characteristics at a high temperature are provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which shows the main structure by a cross sectional view about an example of the normal incidence acoustic characteristic measuring apparatus which concerns on the 1st side surface of one Embodiment of this invention. It is explanatory drawing which shows the main structure by sectional view about the other example of the normal incidence acoustic characteristic measuring apparatus which concerns on the 1st side surface of one Embodiment of this invention. It is explanatory drawing which shows the main structure by a cross sectional view about an example of the normal incidence acoustic characteristic measuring apparatus which concerns on the 2nd side surface of one Embodiment of this invention. It is explanatory drawing which shows the main structure by sectional view about the other example of the normal incidence acoustic characteristic measuring apparatus which concerns on the 2nd side surface of one Embodiment of this invention. It is explanatory drawing which shows the main structure by a cross-sectional view about an example of the normal incidence acoustic characteristic measuring apparatus which concerns on the 3rd side surface of one Embodiment of this invention. It is a flowchart which shows an example of the process performed by the normal incidence acoustic characteristic measuring apparatus which concerns on the 3rd side surface of one Embodiment of this invention. It is explanatory drawing which shows the temperature setting conditions of the normal incidence acoustic characteristic measuring apparatus in the Example which concerns on one Embodiment of this invention. In the Example which concerns on one Embodiment of this invention, it is explanatory drawing which shows an example of the result of having evaluated normal incidence sound absorption coefficient with the normal incidence acoustic characteristic measuring apparatus. In the Example which concerns on one Embodiment of this invention, it is explanatory drawing which shows the other example of the result of having evaluated normal incidence sound absorption coefficient with the normal incidence acoustic characteristic measuring apparatus.

  Hereinafter, an embodiment of the present invention will be described. The present invention is not limited to the example shown in the present embodiment.

  1A, FIG. 1B, FIG. 2A, FIG. 2B, and FIG. 3 show a main configuration in a sectional view of an example of a normal incidence acoustic characteristic measuring apparatus (hereinafter referred to as “this apparatus”) according to the present embodiment. . Hereinafter, the present embodiment will be described with reference to these drawings.

  First, the basic configuration of the apparatus 1 will be described. The apparatus 1 includes a tube main body 10 in which a sound source 20 is disposed at one end 10 a and a test object 30 to be measured is disposed in a tube 10 c, and the sound source 20 and the tube wall 11 of the tube main body 10. The first sound pressure sensor 41 having the first probe 41a disposed at the first position X1 between the test body 30 and the sound source 20 and the test body of the tube wall 11 of the tube body 10 30 and a second sound pressure sensor 42 having a second probe 42a disposed at a second position X2 closer to the test body 30 than the first position X1, and the test Used to measure the normal incident acoustic properties of the body 30.

  In addition, in the normal incidence acoustic characteristic measurement method according to the present embodiment (hereinafter referred to as “the present method”), the sound source 20 is disposed at one end portion 10a, and the test object 30 to be measured is disposed within the tube 10c. A first sound pressure sensor 41 having a tube main body 10 and a first probe 41a disposed at a first position X1 between the sound source 20 and the test body 30 in the tube wall 11 of the tube main body 10. And a second position X2 disposed between the sound source 20 and the test body 30 in the tube wall 11 of the tube body 10 and closer to the test body 30 than the first position X1. Including a second sound pressure sensor 42 having a second probe 42a (for example, the present apparatus 1), and using the apparatus, the normal incident acoustic characteristics of the test body 30 are measured. Is the method.

  The normal incident acoustic characteristics measured by the apparatus 1 and the method are not particularly limited as long as the acoustic characteristics are measured by vertically incident sound waves on the test body 30. For example, the normal incident acoustic absorption characteristics and / or Or a normal incident sound insulation characteristic is mentioned.

  The normal incident sound absorption characteristic is not particularly limited as long as it is a characteristic related to the sound absorption of the test body 30. For example, the normal incident sound absorption coefficient, specific acoustic impedance, complex sound pressure reflection coefficient, sound pressure reflectivity, transfer function, characteristic impedance, propagation One or more selected from the group consisting of a constant, effective density, and bulk modulus can be mentioned, and the normal incident sound absorption coefficient is particularly preferably measured.

  The normal incident sound insulation characteristic is not particularly limited as long as it is a characteristic relating to the sound insulation of the test body 30, and is selected from the group consisting of normal incident sound transmission loss, transfer function, characteristic impedance, propagation constant, effective density, and bulk modulus, for example. In particular, normal incident sound transmission loss is preferably measured.

  When there is a standard for measurement of normal incidence acoustic characteristics, the apparatus 1 and the method are used by a method based on the standard or a method based on the standard with a modification necessary for measurement at a high temperature. It is preferable to perform the measurement according to the above.

  Examples of the standard include JIS A1405-2: 2007, ISO 10534-2: 1998, and ASTM E1050 which specify the transfer function method for measuring the sound absorption coefficient and impedance by an acoustic tube. Is ASTM E 2611.

  The tube body 10 is not particularly limited as long as it is a tubular body that can be used for measurement of normal incidence acoustic characteristics. For example, a tubular body (for example, a so-called acoustic tube) having characteristics defined by the above-mentioned standard is preferably used.

  The cross-sectional shape of the tube body 10 is not particularly limited, but is preferably, for example, a circular shape or a square shape. In the example shown in the drawings of this embodiment, a tube body 10 having a circular cross-sectional shape is used.

  One end portion 10a of the tube body 10 is open, and the sound source 20 is disposed so as to close the opening in the measurement by the apparatus 1 and the method. On the other hand, the other end 10b of the tube body 10 is closed. The tube body 10 shown in the drawings of the present embodiment includes a back plate portion 11a that closes the longitudinal direction of the other end portion 10b. The back plate portion 11a is preferably formed so as to function as a rigid end in the measurement of normal incidence acoustic characteristics.

  In the measurement by the apparatus 1 and the method, the test body 30 is disposed in the tube 10c of the tube body 10. The test body 30 is not particularly limited as long as it can measure the normal incident acoustic characteristics by the apparatus 1 and the method. The shape of the test body 30 is not particularly limited as long as the normal incidence acoustic characteristics can be measured, but the shape defined by the above standard is preferable. That is, for example, the surface 30a on the sound source 20 side of the test body 30 is preferably flat. The test body 30 is disposed so as to close the inside 10 c of the tube in the longitudinal direction of the tube body 10. In the example shown in the drawings of the present embodiment, the test body 30 is a plate-like body arranged so as to close the inside 10 c of the tube in the longitudinal direction of the tube body 10.

  In the example shown in the drawings of the present embodiment, the test body 30 is disposed so as to be in close contact with the back plate portion 11a in the tube 10c of the tube body 10, but is not limited to this. You may form a back air layer (not shown) between the board parts 11a.

  The tube body 10 may include a test body holder (not shown) for holding the test body 30 in the tube 10c. The test body holding part is not particularly limited as long as it is a member suitable for holding the test body 30, but is specified in the above standards (for example, specified in JIS A1405-2: 2007 and JIS A1405-1: 2007). Specimen holder). The test body holding portion is, for example, a tubular body that constitutes the other end portion 10b of the tube body 10 or a midway portion between the one end portion 10a and the other end portion 10b of the tube body 10.

  The sound source 20 is not particularly limited as long as it is a device that can radiate sound waves suitable for measurement of normal incidence acoustic characteristics from the one end 10a of the tube body 10 to the tube interior 10c. For example, a speaker defined by the above standard is preferably used. It is done. In the example shown in the drawings of the present embodiment, a cone-shaped speaker is used as the sound source 20.

  The sound source 20 emits sound waves according to the measurement method. That is, for example, in the measurement by the transfer function method, the sound source 20 radiates broadband noise for forming a plane wave sound field in the tube 10 c of the tube body 10.

  The first sound pressure sensor 41 and the second sound pressure sensor 42 measure the sound pressure at the first position X1 and the second position X2 between the sound source 20 of the tube body 10 and the test body 30, respectively. Provided.

  The first sound pressure sensor 41 includes a first probe 41 a disposed at a first position X <b> 1 between the sound source 20 and the test body 30 in the tube wall 11 of the tube body 10. The second sound pressure sensor 42 is disposed between the sound source 20 and the test body 30 in the tube wall 11 of the tube body 10 and at a second position X2 closer to the test body 30 than the first position X1. And a second probe 42a.

  The first probe 41 a and the second probe 42 a are fixed to the tube wall 11 at a predetermined distance in the longitudinal direction of the tube body 10. Specifically, the first probe 41a and the second probe 42a are respectively inserted into through holes formed in the first position X1 and the second position X2 of the tube wall 11 of the tube body 10, and the tube wall 11 is fixed.

  The first sound pressure sensor 41 and the second sound pressure sensor 42 further include a first microphone body 41b and a second microphone body 42b connected to the first probe 41a and the second probe 42a, respectively. The microphone main bodies 41b and 42b are microphone parts including a diaphragm, for example.

  The probes 41a and 42a are tubular bodies in which cavities for guiding sound waves in the tube 10c of the tube body 10 to the microphone bodies 41b and 42b are formed. That is, one end of the probes 41a and 42a opens to the inner surface 11a of the tube wall 11 of the tube main body 10, and the other end is connected to the microphone main bodies 41b and 42b. Therefore, the sound wave generated in the tube 10c of the tube body 10 propagates from the one end of the probe 41a, 42a to the probe 41a, 42a and is connected to the other end of the probe 41a, 42a. The microphone main bodies 41b and 42b are reached. Thus, the sound pressure sensors 41 and 42 measure the sound pressure via the probes 41a and 42a.

  The sound pressure sensors 41 and 42 are not particularly limited as long as they have the probes 41a and 42a and can measure the sound pressure in the tube 10c, and are preferably realized by, for example, a so-called probe microphone. In the example shown in the drawings of the present embodiment, probe microphones are used as the first sound pressure sensor 41 and the second sound pressure sensor 42.

  In the drawings of the present embodiment, the probes 41a and 42a are shown relatively thick for convenience of explanation, but actually, as the probes 41a and 42a, for example, an outer diameter of 1.5 mm or less, A tubular body having an inner diameter of about 1 mm is preferably used.

  In the measurement by the apparatus 1 and the method, the temperature of the tube 10c (that is, the temperature of the gas (for example, air) filled in the tube 10c) is set to a relatively high desired temperature by heating the tube body 10. Keep within range.

  The first sound pressure sensor 41 and the first sound pressure sensor 41 and the second probe 42a are emitted through the first probe 41a and the second probe 42a while radiating sound waves from the sound source 20 toward the test body 30 into the tube 10c of the heated tube body 10. The sound pressure in the tube 10c is measured by the second sound pressure sensor 42.

  For this reason, in the measurement by this apparatus 1 and this method, the 1st position X1 in which the 1st probe 41a is arrange | positioned among the tube walls 11 of the pipe | tube main body 10, and the 2nd in which the 2nd probe 42a is arrange | positioned. A heater 12 for heating a portion including the position X2 is used.

  The heater 12 is not particularly limited as long as it is a device that can heat the tube body 10 so that the temperature of the tube 10c is maintained within a desired temperature range. For example, the heater 12 preferably includes a heater that generates heat when supplied with electric power. . Specifically, the heater 12 includes, for example, one or more selected from the group consisting of an electric heater, a lamp heater, an oil bath, a water bath, a sand bath, and a salt bath. In the example shown in the drawings of the present embodiment, an electric heater is used as the heater 12. In addition, in order to avoid that the environment around the pipe main body 10 becomes high temperature, you may provide the heat insulating material (not shown) which covers the part in which the heater 12 is arrange | positioned among the pipe walls 11 of the pipe main body 10. FIG.

  As shown in the drawings of the present embodiment, the heater 12 is arranged on the outer side in the radial direction of the tube wall 11 so as to face a portion to be heated in the outer surface 11b of the tube wall 11 of the tube body 10. The position of the heater 12 is not particularly limited as long as the tube wall 11 can be heated so that the temperature in the tube 10c of the tube main body 10 is within a desired temperature range, and the heater 12 is disposed away from the outer surface 11b of the tube wall 11. It may be arranged so as to be in contact with the outer surface 11b.

  In the measurement by the apparatus 1 and the method, as described above, the tube wall 11 of the tube body 10 is heated so that the temperature of the tube 10c of the tube body 10 is maintained within a relatively high desired temperature range.

  Specifically, the heater 12 may be heated so that the temperature in the tube 10c of the tube body 10 and / or the temperature of the tube wall 11 of the tube body 10 becomes 100 ° C. or more, for example, 200 ° C. or more. May be heated to 300 ° C. or higher, may be heated to 400 ° C. or higher, may be heated to 500 ° C. or higher, and may be 600 ° C. or higher. It may be heated to 700 ° C. or higher, or may be heated to 800 ° C. or higher. The upper limit value of the heating temperature is not particularly limited as long as the normal incident acoustic characteristics can be measured by the apparatus 1 and the method, but the heating temperature may be, for example, 1000 ° C. or less.

  The heater 12 may heat the tube body 10 based on a temperature measured by the tube body 10 by a temperature sensor (not shown) disposed on the tube body 10. That is, the heater 12 is, for example, the tube body so that the measured temperature approaches the target temperature under a heating condition determined based on a difference between the measured temperature of the tube body 10 by the temperature sensor and a predetermined target temperature. 10 is heated.

  The heating condition by the heater 12 is determined using, for example, one or more selected from the group consisting of P control, PI control, and PID control. Specific heating conditions include, for example, one or more selected from the group consisting of heating intensity, heating frequency, and heating cycle.

  Specifically, as the heating condition when the heater 12 includes an electric heater, for example, the intensity of heat generated by the electric heater (more specifically, the power supplied to the electric heater), the energization of the electric heater is turned on. One or more selected from the group consisting of the frequency of / OFF, and the period when periodic heating is performed by the electric heater.

  The apparatus 1 may include a heating control unit (not shown) that controls heating by the heater 12. The heating control unit is not particularly limited as long as it performs arithmetic processing for controlling the heating of the tube main body 10 by the heater 12 based on the temperature measured by the temperature sensor, for example, a control including a processor. Realized by the device.

  Specifically, the heating control unit may be realized by, for example, a temperature regulator or a power regulator. In this case, for example, the heating control unit performs a calculation process for PID control based on the measured temperature received from the temperature sensor, and determines a power to be supplied to the heater 12 that is an electric heater (not shown). And an electric power adjustment unit (not shown) that supplies the electric power instructed from the temperature adjustment unit to the heater 12.

  In the measurement by the apparatus 1 and the method, the pipe body 10 is measured based on the sound pressure measured by the first sound pressure sensor 41 and the second sound pressure sensor 42 in a state where the pipe body 10 is heated. The normal incident acoustic characteristics of the test body 30 arranged in the tube 10c are evaluated.

  That is, for example, in the measurement by the transfer function method, based on the sound pressure measured by the first sound pressure sensor 41 and the second sound pressure sensor 42 as shown in the drawings of the present embodiment, the first position X and A transfer function with respect to the second position X2 is calculated, and a normal incident acoustic characteristic is calculated based on the transfer function.

Specifically, for example, in the case of measuring the normal incidence sound absorption coefficient is, the transfer function H ₁₂ is obtained by first formula (I) below.

In the formula (I), _{P 1} is the first measured sound pressure at the position X1 (Unit: Pa) a and, _{P 2} is a second measured sound pressure at the position X2 (Unit: Pa) in There, H ₁₂ is the transfer function between the first position X1 and the second position X2 represented by the ratio of the P ₂ with respect to the P _1, f is the frequency (unit: Hz) with is there.

Then, by using a transfer function _{H 12,} by the following formula (II), normal incidence sound pressure reflectance r (f) is obtained.

  In the above formula (II), t is the distance (unit: m) between the surface 30a on the sound source 20 side of the test body 30 and the first position X1, and s is the first position X1 and the second position X1. The distance from the position X2 (unit: m), k is the wave number (unit: 1 / m), and j is an imaginary unit.

  Then, using the normal incident sound pressure reflectance r, the normal incident sound absorption coefficient α (f) is obtained by the following equation (III).

  The apparatus 1 may include a characteristic calculation unit (not shown) that calculates the normal incident acoustic characteristic of the test body 30 based on the sound pressure measured by the sound pressure sensors 41 and 42. The characteristic calculation unit is realized by, for example, an arithmetic device including a processor (for example, a computer including a CPU). That is, for example, when evaluating the normal incidence acoustic characteristic by the transfer function method, the characteristic calculation unit receives the measured sound pressure from the sound pressure sensors 41 and 42 and executes a calculation process based on the measured sound pressure. A transfer function is calculated, and further, arithmetic processing based on the transfer function is executed to calculate a normal incidence acoustic characteristic.

  Next, the apparatus 1 and the method according to the first aspect of the present embodiment will be described mainly with reference to FIGS. 1A and 1B.

  As shown in FIG. 1A, the apparatus 1 according to the first aspect of the present embodiment has a tube main body 10 in which a sound source 20 is disposed at one end 10a and a test body 30 to be measured is disposed in a tube 10c. A first sound pressure sensor 41 having a first probe 41a disposed at a first position X1 between the sound source 20 and the test body 30 in the tube wall 11 of the tube body 10, and The 2nd probe arrange | positioned between the said sound source 20 and the said test body 30 among the said tube walls 11 of the tube main body 10, and the 2nd position X2 near the said test body 30 from the said 1st position X1. A second sound pressure sensor 42 having 42a, a first temperature sensor 51 for measuring the temperature of the first probe 41a, a second temperature sensor 52 for measuring the temperature of the second probe 42a, The first temperature sensor 51 uses the first profile. Based on the measured temperature of the probe 41a and the measured temperature of the second probe 42a by the second temperature sensor 52, the temperature distribution of the first probe 41a and the temperature distribution of the second probe 42a approach each other. Thus, the temperature adjustment part 60 which heats or cools one or both of the said 1st probe 41a and the said 2nd probe 42a is included.

  Further, in the method according to the first aspect of the present embodiment, the tube body 10 in which the sound source 20 is disposed at one end portion 10a and the test body 30 to be measured is disposed in the tube 10c, and the tube body 10 A first sound pressure sensor 41 having a first probe 41a disposed at a first position X1 between the sound source 20 and the test body 30 and the tube wall of the tube main body 10. 11, a second sound having a second probe 42a disposed between the sound source 20 and the test body 30 and at a second position X2 closer to the test body 30 than the first position X1. A device including the pressure sensor 42 (for example, the present device 1), and radiating a sound wave from the sound source 20 toward the test body 30 into the heated tube 10c of the tube body 10 One probe 41a and the second probe 4 The first sound pressure sensor 41 and the second sound pressure sensor 42 are measured by the first sound pressure sensor 41 and the second sound pressure sensor 42 via a. During the measurement of the sound pressure by, the temperature of the first probe 41a and the second probe 42a is measured, and based on the measured temperature of the first probe 41a and the second probe 42a, Heating or cooling one or both of the first probe 41a and the second probe 42a so that the temperature distribution of the first probe 41a and the temperature distribution of the second probe 42a approach each other; and The first sound pressure sensor 41 and the second sound pressure sensor 4 via the first probe 41a and the second probe 42a, one or both of which are heated or cooled. Based on the measured sound pressure due includes, to evaluate the normal incidence acoustic properties of the test body 30.

  The inventors of the present invention use a pair of probes 41a and 42a fixed to the tube wall 11 of the tube body 10 to obtain the normal incident acoustic characteristics of the test body 30 disposed in the tube 10c of the heated tube body 10. As a result of intensive studies on technical means for improving the accuracy of calculation based on the sound pressure measured by the sound pressure sensors 41 and 42 having the above, the difference in temperature distribution between the pair of probes 41a and 42a is finally It was found uniquely that the accuracy of the normal incident acoustic characteristics calculated in (1) is lowered.

  Therefore, in the present apparatus 1 and the present method, the first probe 41a and the second temperature sensor 52 are used to radiate sound waves from the sound source 20 to the heated tube body 10c of the tube body 10c. While measuring the temperature of the second probe 42a, based on the measured temperature of the probe 41a, 42a, the temperature distribution of the first probe 41a and the temperature distribution of the second probe 42a are close to each other. One or both of the first probe 41a and the second probe 42a are heated or cooled.

  The temperature sensors 51 and 52 are not particularly limited as long as they can measure the temperature of the probes 41a and 42a. For example, a temperature sensor including a temperature sensitive element is preferably used. Examples of the temperature sensitive element include one or more selected from the group consisting of a thermocouple, a resistance temperature detector, a thermistor, and a thermopile (radiation thermometer).

  In the present apparatus 1, one or both of the first temperature sensor 51 and the second temperature sensor 52 measure temperatures at a plurality of locations in the longitudinal direction of one or both of the first probe 41a and the second probe 42a. It is good to do.

  That is, only one of the first temperature sensor 51 and the second temperature sensor 52 determines the temperature at a plurality of locations in one longitudinal direction of the first probe 41a and the second probe 42a that are the one measurement object. Measurement may be performed, or both the first temperature sensor 51 and the second temperature sensor 52 may measure temperatures at a plurality of locations in the longitudinal direction of the first probe 41a and the second probe 42a, respectively. Good.

  In the example shown in FIG. 1A, the first temperature sensor 51 measures the temperature at a plurality of locations in the longitudinal direction of the first probe 41a, and the second temperature sensor 52 is in the longitudinal direction of the second probe 42a. The temperature of several places is measured.

  Specifically, the first temperature sensor 51 includes a plurality of parts spaced apart from each other from the end on the first microphone body 41b side in the longitudinal direction of the first probe 41a toward the end on the tube 10c side of the tube body 10. The first upper stage temperature sensor 51U, the first middle stage temperature sensor 51M, and the first lower stage temperature sensor 51L that measure the temperatures of the three places, that is, the upper stage, the middle stage, and the lower stage are included.

  Similarly, the second temperature sensor 52 has a plurality of locations corresponding to a plurality of locations of the first probe 41a in the longitudinal direction of the second probe 42a, that is, three locations of the upper, middle, and lower steps. A second upper temperature sensor 52U, a second middle temperature sensor 52M, and a second lower temperature sensor 52L are included to measure the respective temperatures.

  The position of each temperature measurement location on the first probe 41a corresponds to the position of each temperature measurement location on the second probe 42a. That is, for example, the distance between the upper temperature measurement position of the first probe 41 a and the outer surface 11 b of the tube wall 11 of the tube main body 10 is the same as that of the upper temperature measurement position of the second probe 42 a and the tube main body 10. The distance from the outer surface 11b of the tube wall 11 is substantially equal.

  Then, the temperature adjusting unit 60 of the present apparatus 1 is based on the measured temperature of the first probe 41 a by the first temperature sensor 51 and the measured temperature of the second probe 42 a by the second temperature sensor 52. One or both of the first probe 41a and the second probe 42a are heated or cooled so that the temperature distribution of the probe 41a approaches the temperature distribution of the second probe 42a.

  That is, if the temperature adjustment unit 60 brings the temperature distribution of the first probe 41a close to the temperature distribution of the second probe 42a, only one of the first probe 41a and the second probe 42a is used. Heating or cooling may be performed, and both the first probe 41a and the second probe 42a may be heated or cooled.

  The temperature adjustment unit 60 may heat at least one or both of the first probe 41a and the second probe 42a. Further, the temperature adjustment unit 60 may cool at least one or both of the first probe 41a and the second probe 42a.

  Further, when one or both of the first temperature sensor 51 and the second temperature sensor 52 measure temperatures at a plurality of locations in the longitudinal direction of one or both of the first probe 41a and the second probe 42a, The temperature adjustment unit 60 may heat or cool part or all of the plurality of portions of one or both of the first probe 41a and the second probe 42a.

  In the example shown in FIG. 1A, the temperature adjustment unit 60 includes a first temperature adjustment unit 61 that heats or cools the first probe 41a, and a second temperature adjustment unit 62 that heats or cools the second probe 42a. , Including.

  Further, the first temperature adjustment unit 61 is a plurality of locations separated from each other from the end on the first microphone main body 41b side in the longitudinal direction of the first probe 41a toward the end on the tube main body 10c side of the tube main body 10. That is, the first upper stage temperature adjustment unit 61U, the first middle stage temperature adjustment unit 61M, and the first lower stage temperature adjustment unit 61L that heat or cool each of the upper, middle, and lower stages are included.

  Similarly, the second temperature adjusting unit 62 has a plurality of locations corresponding to the plurality of locations of the first probe 41a in the longitudinal direction of the second probe 42a, that is, three locations of the upper stage, the middle stage, and the lower stage. The second upper stage temperature adjustment unit 62U, the second middle stage temperature adjustment unit 62M, and the second lower stage temperature adjustment unit 62L are measured.

  The position of each heating or cooling point on the first probe 41a corresponds to the position of each heating or cooling point on the second probe 42a. That is, for example, the distance from the upper heating or cooling position of the first probe 41a to the outer surface 11b of the tube wall 11 of the tube main body 10 is the same as the tube main body 10 from the upper heating or cooling position of the second probe 42a. The distance to the outer surface 11b of the tube wall 11 is substantially equal.

  The temperature adjustment unit 60 is not particularly limited as long as it is a device that can heat or cool the probes 41a and 42a. As the temperature adjusting unit 60 that heats the probes 41a and 42a, for example, a heater that generates heat upon receiving power supply is preferably used. Specifically, for example, an electric heater is preferably used, and a ceramic heater is particularly preferably used. In the example shown in FIGS. 1A and 1B, micro-ceramic heaters are used as the middle stage temperature adjustment units 61M and 62M and the lower stage temperature adjustment units 61L and 62L.

  As the temperature adjusting unit 60 for cooling the probes 41a and 42a, for example, a thermoelectric element is preferably used, and a Peltier element is particularly preferably used. In the example shown in FIGS. 1A and 1B, Peltier elements are used as the upper stage temperature adjustment units 61U and 62U. By using a thermoelectric element (for example, a Peltier element) that can be heated and cooled, the temperature adjustment unit 60 can heat or cool the probes 41a and 42a as necessary. it can.

  The temperature adjustment unit 60 causes the measured temperature to approach the target temperature under a temperature control condition determined based on the difference between the measured temperatures of the probes 41a and 42a by the temperature sensors 51 and 52 and a predetermined target temperature. The probes 41a and 42a may be heated or cooled.

  Specifically, in the example shown in FIG. 1A, the first upper stage temperature sensor 51U, the first middle stage temperature sensor 51M, and the first lower stage temperature sensor 51L, respectively, The temperature of the position is measured, and the temperatures of the upper, middle and lower positions of the second probe 42a are respectively measured by the second upper temperature sensor 52U, the second middle temperature sensor 52M and the second lower temperature sensor 52L. As a result of the measurement, when the measured temperature by the first middle-stage temperature sensor 51M is lower than the target temperature while the measured temperatures at other positions coincide with the target temperature, for example, the first middle-stage temperature adjustment unit 61M By heating the middle position of the first probe 41a, the measured temperature at the middle position of the first probe 41a can be brought close to the target temperature.

  Further, the temperature adjustment unit 60 is a temperature control determined based on the difference between the measured temperature of the first probe 41 a by the first temperature sensor 51 and the measured temperature of the second probe 42 a by the second temperature sensor 52. Under conditions, the first temperature adjustment unit 61 heats or cools the first probe 41a so that the measurement temperature of the first probe 41a approaches the measurement temperature of the second probe 42a, and / or Alternatively, the second temperature adjustment unit 62 may heat or cool the second probe 42a.

  Specifically, in the example shown in FIG. 1A, the first upper stage temperature sensor 51U, the first middle stage temperature sensor 51M, and the first lower stage temperature sensor 51L, respectively, The temperature of the position is measured, and the temperatures of the upper, middle and lower positions of the second probe 42a are respectively measured by the second upper temperature sensor 52U, the second middle temperature sensor 52M and the second lower temperature sensor 52L. As a result of the measurement, the measured temperature by the first middle temperature sensor 51M is lower than the measured temperature by the second middle temperature sensor 52M, while the measured temperatures at the upper stage match and the measured temperatures at the lower stage also match. In this case, for example, by heating the middle position of the first probe 41a by the first middle temperature adjustment unit 61M, The measured temperature of the position of the stage can be brought close to the measured temperature of the position of the middle of the second probe 42a.

  In the example shown in FIG. 1A, the difference between the measured temperature by the first middle temperature sensor 51M and the measured temperature by the second middle temperature sensor 52M, the measured temperature by the first lower temperature sensor 51L, and the second The difference between the temperature measured by the lower temperature sensor 52L and the temperature measured by the lower upper temperature sensor 52L is less than a predetermined value, whereas the difference between the temperature measured by the first upper temperature sensor 51U and the temperature measured by the second upper temperature sensor 52U is different. When the temperature measured by the first upper temperature sensor 51U is higher than the predetermined value and lower than the temperature measured by the second upper temperature sensor 52U, the first probe 41a is used by the first upper temperature adjustment unit 61U. The first upper stage temperature is heated by heating the upper stage position and / or cooling the upper stage position of the second probe 42a by the second upper stage temperature adjustment unit 62U. And temperature measured by sensors 51U, the difference between the temperature measured by the second upper temperature sensor 52U can be reduced below the predetermined value.

  In addition, the heating or cooling by the temperature adjustment unit 60 based on the measured temperature is performed by the temperature adjustment unit 60 that has not heated or cooled the probes 41a and 42a until then newly heating / cooling the probes 41a and 42a. The temperature adjusting unit 60 that has heated or cooled the probes 41a and 42a until then increases the output and heats or cools the probes 41a and 42a more strongly. You may go.

  The temperature adjustment condition by the temperature adjustment unit 60 is determined using, for example, one or more selected from the group consisting of P control, PI control, and PID control. Specific temperature control conditions include, for example, one or more selected from the group consisting of heating or cooling intensity, frequency, and period.

  That is, as a temperature control condition when the temperature adjustment unit 60 is an electric heater, for example, the intensity of heat generated by the electric heater (more specifically, the power supplied to the electric heater), the energization of the electric heater is turned on. One or more selected from the group consisting of the frequency of performing / OFF and the period when performing periodic heating with the electric heater.

  As shown in FIG. 1B, the present apparatus 1 includes a temperature control unit 70 that controls heating or cooling by the temperature adjustment unit 60 based on the temperature measured by the first temperature sensor 51 and the second temperature sensor 52. It is good as well.

  In FIG. 1B, for convenience of explanation, a part of the sound pressure sensors 41 and 42 and a reference number of the temperature sensors 51 and 52 and the temperature adjustment units 60, 61 and 62 shown in FIG. 1A are shown. 1B, the apparatus 1 shown in FIG. 1B also includes the sound pressure sensors 41 and 42, temperature sensors 51 and 52, and temperature adjustment units 60, 61, and 62 similar to the example shown in FIG. 1A. .

  The temperature adjustment control unit 70 is not particularly limited as long as it performs arithmetic processing for controlling heating or cooling by the temperature adjustment unit 60 based on the temperature measured by the temperature sensors 51 and 52. For example, a control device including a processor It is realized by.

  That is, the temperature control unit 70 may be realized by, for example, a temperature regulator or a power regulator. In this case, for example, the temperature control unit 70 performs arithmetic processing for PID control based on the measured temperatures from the temperature sensors 51 and 52 to determine the power to be supplied to the temperature adjustment unit 60 that is a micro heater. This is realized by including a temperature adjusting unit (not shown) and a power adjusting unit (not shown) that supplies power instructed from the temperature adjusting unit to the temperature adjusting unit 60.

  As described above, according to the apparatus 1 and the method according to the first aspect of the present embodiment, the first probe 41a and the first probe 41a and the second probe based on the temperature measured by the first temperature sensor 51 and the second temperature sensor 52 are used. One or both of the two probes 42a are heated or cooled to bring the temperature distribution of the first probe 41a close to the temperature distribution of the second probe 42a, thereby allowing the first probe 41a and the second probe 42a to approach each other. The accuracy of the calculation result of the normal incident acoustic characteristics of the test body 30 based on the measurement temperature via the probe 42a can be effectively increased.

  In addition, in the above-mentioned example, the case where the 1st temperature sensor 51 and the 2nd temperature sensor 52 measure the temperature of the several location in the longitudinal direction of the 1st probe 41a and the 2nd probe 42a, respectively is demonstrated. However, the present invention is not limited to this. For example, the first temperature sensor 51 and the second temperature sensor 52 are provided so as to measure the temperature of one corresponding position of the first probe 41a and the second probe 42a. Then, only one of the first temperature sensor 51 and the second temperature sensor 52 is one or more other in the longitudinal direction of only one of the first probe 41a and the second probe 42a that is the temperature measurement object. It is good also as measuring the temperature of this location.

  Moreover, in the above-mentioned example, although the temperature adjustment part 60 demonstrated the case where both the 1st probe 41a and the 2nd probe 42a were heated or cooled, it is not restricted to this, For example, the temperature adjustment part 60 is Only one of the first probe 41a and the second probe 42a may be heated or cooled.

  That is, for example, the temperature of the first probe 41a is surely lower than the temperature of the second probe 42a depending on conditions such as the environment around the first probe 41a and the second probe 42a. In this case, the temperature adjustment unit 60 heats only the first probe 41a based on the temperature measured by the first temperature sensor 51 and the second temperature sensor 52, so that the first probe 41a The temperature distribution and the temperature distribution of the second probe 42a can be brought close to each other.

  Next, the apparatus 1 and the method according to the second aspect of the present embodiment will be described mainly with reference to FIGS. 2A and 2B.

  As shown in FIGS. 2A and 2B, the device 1 according to the second aspect of the present embodiment has a sound source 20 disposed at one end 10a and a test object 30 to be measured disposed in a tube 10c. A first sound pressure sensor 41 having a tube main body 10 and a first probe 41a disposed at a first position X1 between the sound source 20 and the test body 30 in the tube wall 11 of the tube main body 10. And a second position X2 disposed between the sound source 20 and the test body 30 in the tube wall 11 of the tube body 10 and closer to the test body 30 than the first position X1. A second sound pressure sensor 42 having two probes 42a, and a fluid capable of heat exchange around the first probe 41a and the second probe 42a, and / or the first Probe 41a and second probe 42 DOO thermally conductive member 120a, 120b, by linking at 120c, includes a temperature control unit 100 to approximate the temperature distribution of the temperature distribution and the second probe of the first probe 41a, the.

  In addition, the method according to the second aspect of the present embodiment includes a tube main body 10 in which the sound source 20 is disposed at one end 10a and the test specimen 30 to be measured is disposed in the tube 10c, and the tube main body 10 A first sound pressure sensor 41 having a first probe 41a disposed at a first position X1 between the sound source 20 and the test body 30 of the tube wall 11 and the tube of the tube body 10 A second probe 42a is disposed between the sound source 20 and the test body 30 in the wall 11 and at a second position X2 closer to the test body 30 than the first position X1. A device including the sound pressure sensor 42 (for example, the present device 1), while emitting sound waves from the sound source 20 toward the test body 30 into the heated tube 10c of the tube body 10, First probe 41a and second probe The sound pressure in the tube 10c is measured by the first sound pressure sensor 41 and the second sound pressure sensor 42 via 42a, the first sound pressure sensor 41 and the second sound pressure sensor 42. During the measurement of the sound pressure by means of circulating a heat-exchangeable fluid around the first probe 41a and the second probe 42a and / or the first probe 41a and the second probe By connecting the probe 42a with the thermal conductive member 120, the temperature distribution of the first probe 41a and the temperature distribution of the second probe 42a are brought close to each other, and the fluid is circulated therearound. And / or the first sound pressure sensor via the first probe 41a and the second probe 42a connected by the heat conductive members 120a, 120b, 120c. 1 and based on the measurement sound pressure according to the second sound pressure sensor 42, to evaluate the normal incidence acoustic properties of the test body 30, including.

  That is, for example, as shown in FIG. 2A, the device 1 circulates a heat-exchangeable fluid around the first probe 41 a and the second probe 42 a as the soaking unit 100. A fluid temperature equalizing unit 110 that brings the temperature distribution of the first probe 41a close to the temperature distribution of the second probe 42a is included.

  In this case, a common fluid is circulated around the first probe 41a and the second probe 42a, and heat exchange is performed between the first probe 41a and the second probe 42a and the common fluid. By doing so, the temperature distribution of the first probe 41a and the temperature distribution of the second probe 42a can be effectively brought close to each other.

  In particular, the fluid can be circulated around the first probe 41a and the second probe 42a and can exchange heat with the first probe 41a and the second probe 42a. It is not limited, and either liquid or gas can be used.

  When heating the first probe 41a and the second probe 42a, a fluid having a temperature higher than the temperature of the first probe 41a and / or the temperature of the second probe 42a is circulated. When the one probe 41a and the second probe 42a are cooled, a fluid having a temperature lower than the temperature of the first probe 41a and / or the temperature of the second probe 42a is circulated.

  Specifically, the fluid temperature equalizing unit 110 is realized as a water-cooled cooling device, for example, when water having a temperature lower than the temperature of the first probe 41a and the temperature of the second probe 42a is used as the fluid. When air having a temperature lower than the temperature of the first probe 41a and the temperature of the second probe 42a is used as the fluid, it is realized as an air-cooled cooling device. Further, the fluid temperature equalizing unit 110 that circulates water or air having a temperature higher than the temperature of the first probe 41a and the temperature of the second probe 42a as a fluid is realized as a heating device.

  In the example shown in FIG. 2A, the apparatus 1 is disposed so as to surround the first probe 41a and the second probe 42a, and is higher or lower than the temperature of the first probe 41a and the second probe 42a inside. It includes a fluid soaking unit 110 in which a flow path 111 through which a temperature fluid flows is formed.

  The fluid temperature equalizing unit 110 performs heat exchange between the fluid flowing in the flow path 111 and the first probe 41a and the second probe 42a, thereby the first probe 41a and the second probe 42a. The second probe 42a is heated or cooled.

  In addition, the fluid temperature equalizing unit 110 is not limited to the example illustrated in FIG. 2A, and for example, a common gas may be blown to the first probe 41 a and the second probe 42 a. In this case, the fluid temperature equalizing unit 110 includes, for example, a fan that generates wind by rotating, and is realized as a blower that cools the first probe 41a and the second probe 42a by an air cooling method.

  Further, for example, as shown in FIG. 2B, the present apparatus 1 is configured by connecting a first probe 41 a and a second probe 42 a with heat conductive members 120 a, 120 b, and 120 c as a soaking unit 100. In addition, a connected soaking unit 120 that brings the temperature distribution of the first probe 41a closer to the temperature distribution of the second probe is included.

  In this case, a part of the heat conductive members 120a, 120b, and 120c is connected to the first probe 41a so as to be able to conduct heat, and the other part is connected to the second probe 42a so as to be able to conduct heat. Thus, the first probe 41a and the second probe 42a are connected so as to be able to conduct heat.

  Then, by conducting heat conduction between the first probe 41a and the second probe 42a via the heat conductive members 120a, 120b, and 120c, the temperature distribution of the first probe 41a and the second probe 41a. It is possible to effectively approximate the temperature distribution of the probe.

  The thermal conductive members 120a, 120b, and 120c are not particularly limited as long as they are members having thermal conductivity necessary for soaking the first probe 41a and the second probe 42a. The thermal conductivity of the heat conductive members 120a, 120b, and 120c at 0 ° C. or more and less than 100 ° C. may be 0.1 W / (m · K) or more, and is 1 W / (m · K) or more. It is preferably 10 W / (m · K) or more. The thermal conductivity of the heat conductive members 120a, 120b, and 120c at 100 ° C. or higher and lower than 300 ° C. may be 0.2 W / (m · K) or higher, and 1 W / (m · K) or higher. It is preferable that it is 10 W / (m · K) or more. The thermal conductivity of the heat conductive members 120a, 120b, and 120c at 300 ° C. or higher and lower than 600 ° C. may be 0.5 W / (m · K) or higher, and 1 W / (m · K) or higher. It is preferable that it is 10 W / (m · K) or more. The thermal conductivity of the heat conductive members 120a, 120b, and 120c at 600 ° C. or higher and 1000 ° C. or lower may be 1 W / (m · K) or higher, and is 10 W / (m · K) or higher. It is particularly preferred. In the example shown in FIG. 2B, thermal conductive members 120a, 120b, and 120c having a thermal conductivity at 300 ° C. of 10 W / (m · K) or more are used.

  The material constituting the thermal conductive members 120a, 120b, and 120c is not particularly limited as long as the material has thermal conductivity necessary to soak the first probe 41a and the second probe 42a. , For example, metal (for example, one or more metals selected from the group consisting of copper, aluminum, iron, titanium, lead and molybdenum, and / or an alloy containing one or more metals selected from the group), ceramics (For example, one or more selected from the group consisting of alumina, zirconia and silicon carbide) and one or more selected from the group consisting of carbon. In the example shown in FIG. 2B, metal thermal conductive members 120a, 120b, and 120c are used.

  The shape of the heat conductive members 120a, 120b, and 120c is not particularly limited, and may be, for example, a rod shape, a flat plate shape, a strip shape, a string shape, a plate shape, a net shape, or a tubular shape. In the example shown in FIG. 2B, plate-like heat conductive members 120a, 120b, and 120c are used.

  In the example shown in FIG. 2B, three heat conductive members 120a, 120b, and 120c are used, but the number is not limited to this, and may be one, two, or four. It may be the above.

  Further, one or both of the first probe 41a and the second probe 42a may have at least a part of its outer surface blackened. In this case, since the outer surfaces of the first probe 41a and the second probe 42a are blackened, the first probe 41a and the second probe 42a are rapidly cooled by heat radiation. The one probe 41a and the second probe 42a can be soaked to a temperature near room temperature.

  The material to be blackened is not particularly limited as long as it has a high emissivity. For example, one or more selected from the group consisting of molybdenum disulfide, iron oxide, and zircon is preferably used. The material to be blackened may have, for example, an emissivity at 100 ° C. to 300 ° C. of 0.5 or more, preferably an emissivity at 100 ° C. to 400 ° C. of 0.6 or more, It is more preferable that the emissivity in the range from ℃ to 600 ℃ is 0.7 or more, and it is even more preferable that the emissivity in the range from 100 ℃ to 800 ℃ is 0.8 or more. .9 or more is particularly preferable.

  The method of blackening the outer surfaces of the first probe 41a and the second probe 42a is not particularly limited as long as it is a method of promoting thermal radiation from the outer surface. For example, the emissivity as described above is used. A method of applying a large material to the outer surface, a method of forming a fine uneven structure on the outer surface, and an oxidation treatment of the outer surface (specifically, an oxidation treatment of a metal material constituting the outer surface) Etc.) One or more methods selected from the group consisting of methods are preferably used. The outer surfaces of the probes 41a and 42a are preferably blackened in a range of 60% or more of the total area, and particularly preferably blackened in a range of 80% or more.

  Next, the apparatus 1 and the method according to the third aspect of the present embodiment will be described mainly with reference to FIGS. 3 and 4.

  As shown in FIG. 3, the apparatus 1 according to the third aspect of the present embodiment has a tube body 10 in which a sound source 20 is disposed at one end 10a and a test body 30 to be measured is disposed in a tube 10c. A first sound pressure sensor 41 having a first probe 41a disposed at a first position X1 between the sound source 20 and the test body 30 in the tube wall 11 of the tube body 10, and The 2nd probe arrange | positioned between the said sound source 20 and the said test body 30 among the said tube walls 11 of the tube main body 10, and the 2nd position X2 near the said test body 30 from the said 1st position X1. A second sound pressure sensor 42 having 42a, a first temperature sensor 51 for measuring the temperature of the first probe 41a, a second temperature sensor 52 for measuring the temperature of the second probe 42a, The first sound via the first probe 41a The first measured sound pressure by the sensor 41, the second measured sound pressure by the second sound pressure sensor 42 via the second probe 42a, and the first probe 41a by the first temperature sensor 51. A correction transfer function calculating unit 200 that calculates a correction transfer function based on the measured temperature and the measured temperature of the second probe 42a by the second temperature sensor 52.

  Further, in the method according to the third aspect of the present embodiment, the tube body 10 in which the sound source 20 is disposed at one end 10a and the test body 30 to be measured is disposed in the tube 10c, and the tube body 10 A first sound pressure sensor 41 having a first probe 41a disposed at a first position X1 between the sound source 20 and the test body 30, and the tube wall of the tube body 10. 11, a second sound having a second probe 42a disposed between the sound source 20 and the test body 30 and at a second position X2 closer to the test body 30 than the first position X1. A device including the pressure sensor 42 (for example, the present device 1), and radiating a sound wave from the sound source 20 toward the test body 30 into the heated tube 10c of the tube body 10 One probe 41a and the second probe 4 the first sound pressure sensor 41 and the second sound pressure sensor 42 are used to measure the sound pressure in the tube 10c, and the first sound pressure sensor 41 is connected to the first probe 41a. The first measured sound pressure by the second probe 42a, the second measured sound pressure by the second sound pressure sensor 42, the measured temperature of the first probe 41a, and the second probe Calculating a correction transfer function based on the measured temperature of 42a, and evaluating a normal incident acoustic characteristic of the test body 30 based on the correction transfer function.

  In the program according to the third aspect of the present embodiment (hereinafter referred to as “this program”), the sound source 20 is disposed at one end 10a, and the test object 30 to be measured is disposed in the tube 10c. A first sound pressure sensor 41 having a tube main body 10 and a first probe 41a disposed at a first position X1 between the sound source 20 and the test body 30 in the tube wall 11 of the tube main body 10. And between the sound source 20 and the test body 30 in the tube wall 11 of the tube body 10 and disposed at a second position X2 closer to the test body 30 than the first position X1. A second sound pressure sensor 42 having a second probe 42a, and a program used for measuring normal incident acoustic characteristics using a device (for example, the present device 1), the first probe 41a being The first sound pressure sensor via 1, the second measured sound pressure by the second sound pressure sensor 42 via the second probe 42 a, the measured temperature of the first probe 41 a, and the second This is a program for causing a computer to function as correction transfer function calculating means for calculating a correction transfer function based on the measured temperature of the probe 42a.

In the evaluation of the normal incidence sound characteristic by transfer function, as illustrated in formula (I) below, for the sound pressure P ₁ in the first position X1, as the ratio of the sound pressure P ₂ in the second position X2, the first calculating the transfer function H ₁₂ between the first position X1 and the second position X2, by using the transfer function H _12, to evaluate the normal incidence sound characteristics.

Here, the transfer function H ₁₂ for evaluating the normal incident acoustic characteristics of the test body 30 arranged in the tube 10c of the tube body 10 (hereinafter referred to as “essential transfer function H ₁₂ ”) is the first of the inside of the tube 10c. It is calculated using the sound pressure P ₁ and P ₂ at the first position X1 and the second position X2.

Specifically, in the example shown in FIG. 3, the original transfer function _{H 12,} the sound pressure _{P 1} is measured in the tube 10c side of the end portion Z1 of the first probe 41a, the tube 10c of the second probe 42a It is calculated by using the sound pressure P ₂ measured on the side of the end portion Z2.

However, when using the sound pressure sensors 41 and 42 having the probes 41a and 42a, the sound pressure actually measured by the sound pressure sensors 41 and 42 is the end of the probes 41a and 42a on the microphone main bodies 41b and 42b side. Sound pressures P ₁ ′ and P ₂ ′ measured at Z1 ′ and Z2 ′.

That is, the sound pressure actually measured by the sound pressure sensors 41 and 42 having the probes 41a and 42a is not the sound pressures P ₁ and P ₂ at the ends Z1 and Z2 on the tube 10c side of the probes 41a and 42a, The sound pressures P ₁ ′ and P ₂ ′ reaching the microphone main bodies 41 b and 42 b after passing through the probes 41 a and 42 a.

Then, the sound pressure P ₁ ′ actually measured by the first sound pressure sensor 41 (hereinafter referred to as “first measured sound pressure P ₁ ′”) and actually measured by the second sound pressure sensor 42. Sound pressure P ₂ ′ (hereinafter referred to as “second measured sound pressure P ₂ ′”) and a transfer function H ₁₂ ′ (hereinafter referred to as “measured transfer function H ₁₂ ′”). ) Is represented by the following formula (I ′).

Here, the measured sound pressures P ₁ ′ and P ₂ ′ measured at the ends Z1 ′ and Z2 ′ of the probes 41a and 42a on the microphone main bodies 41b and 42b side pass through the probes 41a and 42a. As compared with the sound pressures P ₁ and P ₂ at the ends Z1 and Z2 on the tube 10c side of the probes 41a and 42a, the sound pressure amplitude is attenuated and / or the sound pressure phase is changed.

However, the environment within the first probe 41a, in the second probe 42a if and have the same environment, the pipe 10c side of the end portion Z1 sound pressure P ₁ with respect to the first of the first probe 41a Attenuation of the amplitude and / or phase change of the measured sound pressure P ₁ ′ and the amplitude of the second measured sound pressure P ₂ ′ with respect to the sound pressure P ₂ at the end Z2 on the tube 10c side of the second probe 42a. Since the attenuation and / or phase change is the same, the actual transfer function H ₁₂ ′ calculated by the above formula (I ′) as the ratio thereof is the original transfer function H ₁₂ calculated by the above formula (I). Therefore, there is no problem in calculating the normal incident acoustic characteristics using the actually measured transfer function H ₁₂ ′.

That is, for example, a transfer function _{H 1} between the first end portions of Z1 and microphone body 41b side of the pipe 10c side in the probe 41a Z1', as formula (IV) below, the end portion It is defined as the ratio of the first measured sound pressure P ₁ ′ to the sound pressure P _{1 at} Z1, and is defined between the end Z2 on the tube 10c side and the end Z2 ′ on the microphone main body 42b side in the second probe 42a. the transfer function H _2, as the following formula (V), _'when defined as the ratio of the measured transfer function H _12' sound pressure P ₂ with respect to the second measuring sound pressure P ₂ at the end Z2 are the following It can be expressed as in formula (VI).

If the attenuation of the sound pressure amplitude and / or phase change in the first probe 41a matches the attenuation of the sound pressure amplitude and / or phase change in the second probe 42a, the first a transfer function _{H 1} in one probe 41a, the transfer function _{H 2} and coincide in a second probe 42a, the measured transfer function _{H 12} 'becomes possible to match the original transfer function _{H 12.}

  However, for example, when the sound pressure is measured by heating the tube main body 10, it is not easy to make the environment in the first probe 41a coincide with the environment in the second probe 42a.

  When the environment in the first probe 41a and the environment in the second probe 42a are different, for example, the temperature in the first probe 41a is different from the temperature in the second probe 42a. Since the speed of sound changes with temperature, the speed of sound in the first probe 41a and the speed of sound in the second probe 42a are different. As a result, for example, in the first probe 41a The attenuation of the sound pressure amplitude and / or the change in the phase of the sound pressure is different from the attenuation of the amplitude of the sound pressure and / or the change in the phase of the sound pressure in the second probe 42a.

Thus, the attenuation of the sound pressure amplitude and / or the change in the phase of the sound pressure in the first probe 41a, and the attenuation of the sound pressure amplitude and / or the change in the phase of the sound pressure in the second probe 42a. Are different from each other, the first measured sound pressure P ₁ ′ measured after passing through the first probe 41a and the second measured sound pressure P ₂ measured after passing through the second probe 42a. The measured transfer function H ₁₂ ′ calculated on the basis of “′” originally does not match the transfer function H ₁₂ .

Therefore, in this case, the normal incidence acoustic characteristic calculated using the actually measured transfer function H ₁₂ ′ does not match the normal incidence acoustic characteristic originally calculated using the transfer function H ₁₂ , and the calculation result is accurate. Problems arise. This decrease in accuracy becomes more prominent as the deviation between the measured transfer function H ₁₂ ′ and the inherent transfer function H ₁₂ increases.

Therefore, in the present apparatus 1 and the present method, the sound generated by the first sound pressure sensor 41 and the second sound pressure sensor 42 via the first probe 41a and the second probe 42a while the tube body 10 is heated. During the measurement of the pressure, the temperature of the first probe 41a and the second probe 42a is measured, the sound pressure measured by the first sound pressure sensor 41 and the second sound pressure sensor, and the first probe Based on the measured temperature of 41a and the measured temperature of the second probe 42a, an unprecedented transfer function (hereinafter referred to as "corrected transfer function H12 _(am) ") is calculated.

The correction transfer function H _{12 (am)} is the measured transmission function H _{12 'described} above corresponds to the correction of the transfer function has been added to that based on the measured temperature of the measuring temperature and the second probe 42a of the first probe 41a .

  Thus, the transfer function is calculated using not only the sound pressure measured by the first sound pressure sensor 41 and the second sound pressure sensor but also the measured temperature of the first probe 41a and the measured temperature of the second probe 42a. It has never been done before.

By calculating the normal incident acoustic characteristic using the corrected transfer function H _{12 (am)} , the normal incident acoustic characteristic can be calculated with higher accuracy than when the actually measured transfer function H ₁₂ ′ is used.

Here, as shown in FIG. 3, the present apparatus 1 has a first sound pressure P ₁ ′ measured by the first sound pressure sensor 41 via the first probe 41 a and a second value via the second probe 42 a. The second measurement sound pressure P ₂ ′ by the sound pressure sensor 42, the measurement temperature of the first probe 41 a by the first temperature sensor 51, and the measurement of the second probe 42 a by the second temperature sensor 52. A correction transfer function calculating unit 200 that calculates a correction transfer function H _{12 (am)} based on the temperature is included.

The corrected transfer function calculation unit 200 is based on the first measured sound pressure P ₁ ′, the second measured sound pressure P ₂ ′, the measured temperature of the first probe 41a, and the measured temperature of the second probe 42a. It is not particularly limited as long as it performs arithmetic processing for calculating the corrected transfer function H _{12 (am)} , and is realized by, for example, an arithmetic device including a processor (for example, a computer including a CPU).

Here, the program is installed in the computer, so that the first measured sound pressure P ₁ ′ by the first sound pressure sensor 41 through the first probe 41a and the second probe 42a through the second probe 42a are used. The second measured sound pressure P ₂ ′ by the second sound pressure sensor 42, the measured temperature of the first probe 41 a by the first temperature sensor 51, and the second probe 42 a by the second temperature sensor 52. The computer is caused to function as a corrected transfer function calculating means for calculating the corrected transfer function H12 _(am) based on the measured temperature. Therefore, the correction transfer function calculation unit 200 of the apparatus 1 may be realized by a computer in which the program is installed.

  In addition, the program may be a program that causes a computer to function as means for executing part or all of the processing in the apparatus 1 and the method described above. That is, the processing in the device 1 and the method may be executed by a control device included in the computer operating according to the program recorded in a computer-readable recording medium.

  Specifically, the program includes a measurement temperature receiving means for receiving the measurement temperature of the first probe 41a by the first temperature sensor 51 and the measurement temperature of the second probe 42a by the second temperature sensor 52, and the correction described above. It is good also as what makes a computer function as a transfer function calculation means.

  The program also includes a first measured sound pressure by the first sound pressure sensor 41 via the first probe 41a and a second measured sound by the second sound pressure sensor 42 via the second probe 42a. The computer may function as a measurement sound pressure receiving means for receiving pressure and the correction transfer function calculating means.

  In addition, this program may cause a computer to function as the above-described measurement temperature receiving unit, measurement sound pressure receiving unit, and correction transfer function calculation unit.

FIG. 4 is a flowchart showing an example of processing executed by the apparatus 1 realized by a computer in which the program is installed. In the example shown in FIG. 4, in the process S <b> 1, the present apparatus 1 radiates a sound wave from the sound source 20 toward the test body 30 into the tube 10 c of the heated tube body 10, while the first probe 41 a and the second probe 1. The first measurement sound pressure P ₁ ′ and the second measurement sound pressure P ₂ ′ measured by the first sound pressure sensor 41 and the second sound pressure sensor 42 are acquired via the probe 42a.

  Further, in the process S2, the apparatus 1 determines the temperature of the first probe 41a and the temperature of the second probe 42a measured by the first temperature sensor 51 and the second temperature sensor 52 during the measurement of the sound pressure. get.

Further, in the process S3, the apparatus 1 performs the first measurement sound pressure P ₁ ′, the second measurement sound pressure P ₂ ′, the measurement temperature of the first probe 41a, and the measurement temperature of the second probe 42a. Based on the above, a corrected transfer function H _{12 (am)} is calculated.

And this apparatus 1 calculates the normal incidence acoustic characteristic of the test body 30 based on correction | amendment transfer function H12 _(am) in process S4.

  Note that, as described above, this program may be recorded on a computer-readable recording medium. The computer-readable recording medium is not particularly limited as long as it can record a program and can be read by a computer. For example, a magnetic disk (for example, a hard disk), a semiconductor memory (for example, a semiconductor memory) , A non-volatile semiconductor memory such as a flash memory) and one or more selected from the group consisting of optical disks (for example, DVD and CD) are preferably used.

Specific methods of calculating the correction transfer function H _{12 (am),} in addition to the first measurement sound pressure P _{1 'and} the second measurement sound pressure P _2', the measured temperature of the first probe 41a and a The method is not particularly limited as long as the measurement temperature of the second probe 42a is used. For example, the first measurement sound pressure P ₁ ′ and the second measurement sound pressure P ₂ ′ and the first probe 41a The difference between the attenuation of the sound pressure amplitude in the first probe 41a and the attenuation of the sound pressure amplitude in the second probe 42a, obtained from the measurement temperature and the measurement temperature of the second probe 42a, and Alternatively, it may be calculated based on a characteristic value relating to a difference between a change in the sound pressure phase in the first probe 41a and a change in the sound pressure phase in the second probe 42a.

  The characteristic values relating to this difference include, for example, (i) sound velocity, (ii) propagation constant, (iii) impedance, (iv) admittance, and (v) in the first probe 41a and the second probe 42a. One or more selected from the group consisting of effective bulk modulus and effective density can be mentioned.

That is, regarding the above (i), in the present apparatus 1, the correction transfer function calculation unit 200 includes, for example, the first measurement sound pressure P ₁ ′, the second measurement sound pressure P ₂ ′, and the first probe 41a. The correction transfer function H12 _(am) is calculated based on the sound speed in the first probe 41a and the sound speed in the second probe 42a obtained from the measurement temperature and the measurement temperature of the second probe 42a. Also good.

Specifically, for example, the temperature of a section having a predetermined length L in the longitudinal direction in the first probe 41a is T1, and corresponds to the section of the first probe 41a in the longitudinal direction in the second probe 42a. H ₂ , which is a ratio of the transfer function H ₂ in the second probe 42 a to the transfer function H ₁ in the first probe 41 a when the temperature of the section of the predetermined length L at the position to be moved is T _2. / H ₁ is represented by the following formula (VII). Except for the section of the length L, it is assumed that there is no temperature difference between the first probe 41a and the second probe 42a.

  In the formula (VII), c1 is a sound velocity (unit: m / s) in the first probe 41a having a temperature T1, and c2 is a sound velocity (unit: m) in the second probe 42a having a temperature T2. / S), f is the frequency (unit: Hz), L is the length of the section (unit: m), and j is an imaginary unit.

Therefore, since the relationship between the temperature in the tube and the sound velocity is known, the sound velocity c1 in the section is obtained from the temperature T1 of the section of the first probe 41a measured by the first temperature sensor 51, and the second by obtaining sound velocity c2 of the inner section from the temperature T2 of the section of the second probe 42a measured by the temperature sensor 52, by the above formula (VII), a transfer function ratio H _{2 /} H ₁ is calculated.

Furthermore, the measured transfer function H ₁₂ ′ calculated by the above formula (I ′) based on the transfer function ratio H ₂ / H ₁ , the first measured sound pressure P ₁ ′, and the second measured sound pressure P ₂ ′. When, by using, as a transfer function corresponding to the original transfer function _{H 12} of formula (VI), the correction transfer function _{H 12 (am)} is calculated.

Then, by calculating the normal incidence acoustic characteristic using the corrected transfer function H _{12 (am)} thus obtained (for example, instead of the transfer function H ₁₂ originally by the above formula (II) and formula (III)). By using the corrected transfer function H _{12 (am)} , the normal incident sound absorption coefficient can be calculated.) Compared with the case where the measured transfer function H ₁₂ ′ is used as it is, the highly accurate normal incident acoustic characteristic is calculated. Can do.

  Note that the sound speed at the specific temperatures T1 and T2 used in the calculation according to the above example is calculated and used by substituting the specific temperatures T1 and T2 into a calculation formula indicating the correlation between the temperature and the sound speed, for example. May be.

  That is, for example, the speed of sound c in a circular tube having an inner diameter D at a temperature T can be expressed by the following formula (VIII) (Source: JF Allard and N. Atalla, Propagation of Sound in Porous Media, John Wiley & Sons, Inc.) (2009)).

In the formula (VIII), ρ is the effective density of air (unit: kg / m ³ ), and K is the effective bulk modulus (unit: Pa) of air. Here, ρ is represented by the following formula (IX), and K is represented by the following formula (X).

In Formula (IX) and Formula (X), P ₀ is the pressure of air inside the circular tube (unit: Pa), and ρ ₀ (T) is the density of air at temperature T (unit: kg / m ³ ). Γ (T) is the specific heat ratio (unit: dimensionless) of air at temperature T, η (T) is the viscosity (unit: Pa · s) of air at temperature T, and Pr (T) is temperature The Prandtl number of air in T (unit: dimensionless), ρ is the effective density of air (unit: kg / m ³ ), and K is the effective bulk modulus (unit: Pa) of air. The values of ρ ₀ (T), γ (T), η (T), and Pr (T) can also be obtained from known literature.

  In addition, the sound speed at the specific temperatures T1 and T2 used in the calculation according to the above-described example is, for example, from a table in which a plurality of temperatures and sound speeds at the respective temperatures are recorded in association with each other. The sound speed corresponding to T2 may be read and used. Such calculation formulas and tables relating to the relationship between temperature and sound speed are stored in advance in a storage device (hard disk, semiconductor memory, etc.) not shown, and the correction transfer function calculation unit 200 reads out from the storage device and uses it for calculation. It is good as well.

Regarding (ii), in the present apparatus 1, for example, the first measured sound pressure P ₁ ′ and the second measured sound pressure P ₂ ′, the measured temperature of the first probe 41a, and the second probe 42a. The corrected transfer function H12 _(am) may be calculated based on the propagation constant in the first probe 41a and the propagation coefficient in the second probe 42a obtained from the measured temperature.

Specifically, for example, the temperature of a section having a predetermined length L in the longitudinal direction in the first probe 41a is T1, and corresponds to the section of the first probe 41a in the longitudinal direction in the second probe 42a. H ₂ , which is a ratio of the transfer function H ₂ in the second probe 42 a to the transfer function H ₁ in the first probe 41 a when the temperature of the section of the predetermined length L at the position to be moved is T _2. / H ₁ is represented by the following formula (XI). Except for the section of the length L, it is assumed that there is no temperature difference between the first probe 41a and the second probe 42a.

  In the formula (XI), Γ1 is a propagation constant (unit: 1 / m) in the first probe 41a having a temperature T1, and Γ2 is a propagation constant (unit in the second probe 42a having a temperature T2). : 1 / m), L is the length of the section (unit: m), and j is an imaginary unit.

Therefore, since the relationship between the temperature in the tube and the propagation constant is known, the propagation constant Γ1 in the section is obtained from the temperature T1 in the section of the first probe 41a measured by the first temperature sensor 51. If the propagation constant Γ2 in the section is obtained from the temperature T2 of the section of the second probe 42a measured by the second temperature sensor 52, the transfer function ratio H ₂ / H ₁ is calculated by the above formula (XI). Is done.

Furthermore, the measured transfer function H ₁₂ ′ calculated by the above formula (I ′) based on the transfer function ratio H ₂ / H ₁ , the first measured sound pressure P ₁ ′, and the second measured sound pressure P ₂ ′. When, by using, as a transfer function corresponding to the original transfer function _{H 12} of formula (VI), the correction transfer function _{H 12 (am)} is calculated.

Then, by calculating the normal incidence acoustic characteristic using the corrected transfer function H _{12 (am)} thus obtained (for example, instead of the transfer function H ₁₂ originally by the above formula (II) and formula (III)). By using the corrected transfer function H _{12 (am)} , the normal incident sound absorption coefficient can be calculated.) Compared with the case where the measured transfer function H ₁₂ ′ is used as it is, the highly accurate normal incident acoustic characteristic is calculated. Can do.

  Note that the propagation constants at the specific temperatures T1 and T2 used in the calculation according to the above-described example are calculated by substituting the specific temperatures T1 and T2 into a calculation formula indicating the correlation between the temperature and the propagation constant, for example. May be used.

  That is, for example, the propagation constant Γ in a circular tube having an inner diameter D at a temperature T can be expressed by the following formula (XII) (Source: JF Allard and N. Atalla, Propagation of Sound in Porous Media, John Wiley & Sons, Inc. (2009)).

In the formula (XII), ρ is the effective density of air (unit: kg / m ³ ), K is the effective bulk modulus of elasticity (unit: Pa), and f is the frequency (unit: Hz). j is an imaginary unit. Here, ρ is represented by the following formula (XIII), and K is represented by the following formula (XIV).

In Formula (XIII) and Formula (XIV), P ₀ is the pressure of air inside the circular tube (unit: Pa), and ρ ₀ (T) is the density of air at temperature T (unit: kg / m ³ ). Γ (T) is the specific heat ratio (unit: dimensionless) of air at temperature T, η (T) is the viscosity (unit: Pa · s) of air at temperature T, and Pr (T) is temperature The Prandtl number of air in T (unit: dimensionless), ρ is the effective density of air (unit: kg / m ³ ), and K is the effective bulk modulus (unit: Pa) of air. The values of ρ ₀ (T), γ (T), η (T), and Pr (T) can also be obtained from known literature.

Regarding (iii), in the present apparatus 1, for example, the first measurement sound pressure P ₁ ′ and the second measurement sound pressure P ₂ ′, the measurement temperature of the first probe 41a, and the second probe The correction transfer function H12 _(am) may be calculated based on the impedance in the first probe 41a and the impedance in the second probe 42a obtained from the measured temperature of 42a.

Regarding (iv), in the present apparatus 1, for example, the first measurement sound pressure P ₁ ′ and the second measurement sound pressure P ₂ ′, the measurement temperature of the first probe 41a, and the second probe The correction transfer function H12 _(am) may be calculated based on the admittance in the first probe 41a and the admittance in the second probe 42a obtained from the measured temperature of 42a.

Regarding the above (v), in the present apparatus 1, for example, the first measured sound pressure P ₁ ′ and the second measured sound pressure P ₂ ′, the measured temperature of the first probe 41a, and the second probe Based on the effective bulk modulus and effective density in the first probe 41a and the effective bulk modulus and effective density in the second probe 42a obtained from the measured temperature of 42a, the corrected transfer function H12 _{(am )} May be calculated.

In the present apparatus 1 and method, the first measurement sound pressure P ₁ ′, the second measurement sound pressure P ₂ ′, the measurement temperature of the first probe 41a, and the measurement temperature of the second probe 42a, calculation of the correction transfer function H _{12 (am)} based on the on the calculation process, if it contains operations equivalent to the calculation of the measured temperature and the correction transfer function H _{12 (am),} described in the above example It is not restricted to the aspect which uses such a type | formula.

In addition, (i) sound velocity, (ii) propagation constant in the first probe 41a and the second probe 42a, the first measurement sound pressure P ₁ ′, the second measurement sound pressure P ₂ ′, The calculation of the corrected transfer function H _{12 (am)} based on (iii) impedance, (iv) admittance, and (v) one or more selected from the group consisting of effective bulk modulus and effective density is also performed in the calculation process. 1 or more selected from the group consisting of (i) sound velocity, (ii) propagation constant, (iii) impedance, (iv) admittance, and (v) effective bulk modulus and effective density, or the corrected transfer function As long as an operation corresponding to the calculation of H _{12 (am)} is included, the present invention is not limited to the mode using the formula described in the above example.

  Next, specific examples according to the present embodiment will be described.

  Using this apparatus 1 shown in FIGS. 1A and 1B, the normal incident sound absorption coefficient of the test body 30 was evaluated by the transfer function method. As the tube body 10, a stainless steel cylindrical body (inner diameter 40 mm, outer diameter 50 mm, length 800 mm) in which one end portion 10 a in the longitudinal direction was opened and the other end portion 10 b was closed was used.

  A cone type speaker as a sound source 20 was arranged at one end 10 a of the tube body 10, and a disk-shaped mat made of inorganic fibers was arranged as a test body 30 at the other end 10 b. In the range of about 450 mm in the longitudinal direction from the other end portion 10b of the tube main body 10, as a heater 12 for heating the tube main body 10, a heating wire fixed to the inner peripheral surface of a cylindrical molded body made of inorganic fibers is used. It arrange | positioned so that the outer peripheral surface 11b of the pipe wall 11 of the pipe | tube main body 10 might be covered.

  In addition, a commercially available K-type thermocouple is disposed as a temperature sensor for measuring the temperature of the tube wall 11 at a plurality of locations in the longitudinal direction of the tube wall 11 of the tube body 10 in the range where the heater 12 is disposed. A control device for heating the tube body 10 by the heater 12 by PID control based on measured temperatures from the plurality of temperature sensors was also prepared.

  As the sound pressure sensors 41 and 42, commercially available probe microphones having probes 41a and 42a (inner diameter 1 mm, outer diameter 1.25 mm, length 160 mm), which are stainless steel cylinders, were used.

  The first probe 41a and the second probe 42a are inserted into through holes formed in the first position X1 and the second position X2 of the tube wall 11 of the tube body 10 and fixed to the tube wall 11. . The distance between the first position X1 and the second position X2 was 30 mm.

  A jig (10 mm × 25 mm, thickness 6 mm), which is an aluminum plate-like piece having excellent thermal conductivity, is fixed to a position approximately 30 mm from the end face on the tube 10c side of each probe 41a, 42a. A commercially available K-type thermocouple as the lower temperature sensors 51L and 52L is fixed to a part of the heater, and a commercially available micro ceramic heater as the lower temperature controllers 61L and 62L is fixed to the other part of the jig. did.

  Similarly, a jig is fixed at a position of about 50 mm from the end face on the tube 10c side of each probe 41a, 42a, and a commercially available K-type thermocouple as a middle stage temperature sensor 51M, 52M is attached to a part of the jig. In addition to fixing, commercially available micro ceramic heaters as the middle temperature adjusting parts 61M and 62M were fixed to the other part of the jig.

  Similarly, a jig is fixed at a position of about 90 mm from the end face on the tube 10c side of each probe 41a, 42a (about 60 mm from the end face on the microphone main body 41b, 42b side), and an upper temperature is applied to a part of the jig. Commercially available K-type thermocouples as the sensors 51U and 52U were fixed, and commercially available Peltier elements as the upper temperature adjusting parts 61U and 62U were arranged on the other part of the jig.

  In the measurement of the normal incidence acoustic characteristics, first, the pipe body is heated by the heater 12 that is PID-controlled based on the measurement temperature so that the temperature measured by the temperature sensor disposed on the pipe wall 11 of the pipe body 10 is 300 ° C. Ten tube walls 11 were heated.

  Next, while radiating sound waves from the sound source 20 toward the test body 30 into the tube interior 10c of the heated tube body 10, the first sound pressure sensor 41 and the first sound pressure sensor 41 and the second probe 42a are emitted via the first probe 41a and the second probe 42a. The sound pressure in the pipe 10c was measured by the second sound pressure sensor 42.

  During the measurement of the sound pressure by the first sound pressure sensor 41 and the second sound pressure sensor 42, the first probe 41 a and the second probe are detected by the first temperature sensor 51 and the second temperature sensor 52. The temperature of the first probe 41a and the second probe 41a and the second probe 42a are measured so that the measured temperature becomes a target temperature based on the measured temperatures of the first probe 41a and the second probe 42a. The probe 42a was heated or cooled.

  That is, at each of the upper, middle, and lower positions of the probes 41a and 42a, the measured temperature at each position becomes the predetermined target temperature shown in FIG. 5 by PID control based on the measured temperature by the temperature sensors 51 and 52. As described above, the probes 41 a and 42 a were heated or cooled by the temperature adjusting units 61 and 62.

  Specifically, as shown in FIG. 5, in the aspect A, the lower probe temperature adjusting unit 61L is configured so that the measured temperature by the lower temperature sensors 51L and 52L is 300 ° C. in both the first probe 41a and the second probe 42a. , 62L, and heating by the middle stage temperature adjusting units 61M, 62M so that the measured temperature by the middle stage temperature sensors 51M, 52M is 260 ° C., so that the measured temperature by the upper stage temperature sensors 51U, 52U is 28 ° C. Then, cooling was performed by the upper temperature adjustment units 61U and 62U. Thus, in the aspect A, the temperature distribution in the longitudinal direction of the first probe 41a and the temperature distribution in the longitudinal direction of the second probe 42a are matched.

  On the other hand, as shown in FIG. 5, as other aspects B to E, a state was created in which the temperature distribution in the longitudinal direction of the first probe 41a and the temperature distribution in the longitudinal direction of the second probe 42a were different.

  That is, in the mode B, the heating by the first middle temperature adjusting unit 61M was performed so that the temperature measured by the middle temperature sensor 51M of the first probe 41a was 250 ° C., and the others were the same as the mode A.

  In aspect C, heating was performed by the first middle temperature adjustment unit 61M so that the temperature measured by the middle temperature sensor 51M of the first probe 41a was 240 ° C., and the others were the same as in aspect A.

  In aspect D, heating was performed by the first intermediate temperature adjusting unit 61M so that the temperature measured by the intermediate temperature sensor 51M of the first probe 41a was 210 ° C., and the others were the same as in aspect A.

  In the aspect E, heating was performed by the second middle stage temperature adjustment unit 62M so that the temperature measured by the middle stage temperature sensor 52M of the second probe 42a was 250 ° C., and the others were the same as in the aspect A.

In each of these aspects A to E, the first measured sound pressure P ₁ ′ measured by the first sound pressure sensor 41 via the first probe 41a and the second via the second probe 42a. _'based on the actual measurement the transfer function H _12' second measuring sound pressure P ₂ measured by second sound pressure sensor 42 to calculate the (above formula (I')), the measured transmission function H ₁₂ ' Was used to calculate the normal incident sound absorption coefficient of the test body 30 (the above formulas (II) and (III)).

  FIG. 6 shows the relationship between the normal incident sound absorption coefficient (dimensionalless) calculated in each of the aspects A to E and the frequency (Hz).

  As shown in FIG. 6, the normal incident sound absorption coefficient calculated in the aspects B to E in which the temperature distribution of the first probe 41a and the temperature distribution of the second probe 42a are different is the temperature distribution of the first probe 41a. It was confirmed that the normal incident sound absorption coefficient is different from that calculated in the aspect A in which the temperature distribution of the second probe 42a is matched.

  Furthermore, as the deviation between the temperature distribution of the first probe 41a and the temperature distribution of the second probe 42a increases, that is, the measured temperature at the middle position of the first probe 41a and the middle stage of the second probe 42a. It was confirmed that the difference between the calculated normal incident sound absorption coefficient and that in the aspect A also increases as the difference between the measured temperature and the measured temperature increases.

  That is, for example, when the temperature distribution between the probes 41a and 42a differs as in the modes B to E by not performing any temperature adjustment of the probes 41a and 42a, the probe 41a as in the mode A. , 42a, it is confirmed that the temperature distribution between the probes 41a, 42a can be matched to obtain a more accurate normal incidence acoustic characteristic.

Next, a corrected transfer function H _{12 (am)} obtained by adding correction based on the temperature difference at the middle position shown in FIG. 5 to the actually measured transfer function H ₁₂ ′ obtained in the modes B to E is calculated, and the corrected transfer The normal incidence sound absorption coefficient of the test body 30 was calculated using the function H12 _(am) .

That is, for example, in the aspect B, the temperature of the middle position of the first probe 41a is 250 ° C., which is 10 ° C. lower than the temperature 260 ° C. of the middle position of the second probe 42a. Assuming that the temperature of the first probe 41a is 255 ° C., which is 5 ° C. uniformly lower than the temperature of the second probe 42a, in a 50 mm long section centered on the middle position, the speed of sound c1 at a temperature 255 ° C. of the section of the probe 41a, based on the speed of sound c2 at a temperature 260 ° C. of the corresponding section of the second probe 42a, for the transfer function _{H 1} of the in the first probe 41a, the calculating a _H 2 / _{H 1} is the ratio of the transfer function of _{H 2} in the second probe 42a (the above formula (VII)), and the transfer function ratio _H 2 / _{H 1,} the actual First measuring sound pressure P _{1 'and} the second measurement sound pressure P _2' actual transfer functions H ₁₂ calculated from the obtained measured _'by using the _(above formula (I')), the compensated transmission The function H _{12 (am)} was calculated (the above formula (VI)). Then, using this corrected transfer function H _{12 (am)} , the normal incident sound absorption coefficient of the test body 30 was calculated (the above formulas (II) and (III)).

Similarly, for each of the modes C to E, the first measurement sound pressure P ₁ ′ and the second measurement sound pressure P ₂ ′ obtained by actual measurement and the middle positions of the probes 41 a and 42 a are similarly obtained. Based on this temperature difference, a corrected transfer function H _{12 (am)} was calculated, and the normal incident sound absorption coefficient of the specimen 30 was calculated using the corrected transfer function H _{12 (am)} .

FIG. 7 shows the relationship between the normal incident sound absorption coefficient (dimensionalless) calculated using the corrected transfer function H _{12 (am} ) and the frequency (Hz) for each of the modes B to E. For comparison, FIG. 7 also shows the normal incidence sound absorption coefficient calculated using the measured transfer function H ₁₂ ′ in the same manner as that shown in FIG.

As shown in FIG. 7, the normal incident sound absorption coefficient of the modes B to E calculated using the corrected transfer function H _{12 (am)} instead of the actually measured transfer function H ₁₂ ′ is between the probes 41 a and 42 a by adjusting the temperature. It was close to the normal incident sound absorption coefficient of the aspect A in which the temperature distribution was matched.

That is, by using the correction transfer function H12 _(am) calculated in consideration of the temperature difference between the probes 41a and 42a, the temperature distribution between the probes 41a and 42a is matched by temperature adjustment. It was confirmed that a highly accurate normal incidence sound absorption coefficient can be obtained.

Claims (5)

A sound source is arranged at one end, and a tube body in which a test object to be measured is arranged in the tube,
A first sound pressure sensor having a first probe disposed at a first position between the sound source and the specimen in the tube wall of the tube body;
A second sound having a second probe arranged between the sound source and the test body in the tube wall of the tube main body and at a second position closer to the test body than the first position. A pressure sensor;
A first temperature sensor for measuring the temperature of the first probe;
A second temperature sensor for measuring the temperature of the second probe;
A first measured sound pressure by the first sound pressure sensor via the first probe, a second measured sound pressure by the second sound pressure sensor via the second probe, the first A correction transfer function calculating unit that calculates a correction transfer function based on the temperature measured by the first probe by the temperature sensor and the temperature measured by the second probe by the second temperature sensor;
A normal incidence acoustic characteristic measuring apparatus including: The correction transfer function calculation unit is obtained from the first measurement sound pressure and the second measurement sound pressure, the measurement temperature of the first probe, and the measurement temperature of the second probe, Difference between attenuation of sound pressure amplitude in the probe and attenuation of sound pressure amplitude in the second probe, and / or change in phase of sound pressure in the first probe and in the second probe Calculating the correction transfer function based on the characteristic value regarding the difference from the change in the phase of the sound pressure in
The normal incidence acoustic characteristic measuring apparatus according to claim 1 . The characteristic values are: (i) sound velocity, (ii) propagation constant, (iii) impedance, (iv) admittance, and (v) effective bulk modulus in the first probe and in the second probe. One or more selected from the group consisting of effective density,
The normal incidence acoustic characteristic measuring apparatus according to claim 2 . A sound source is arranged at one end, and a tube body in which a test object to be measured is arranged in the tube,
A first sound pressure sensor having a first probe disposed at a first position between the sound source and the specimen in the tube wall of the tube body;
A second sound having a second probe arranged between the sound source and the test body in the tube wall of the tube main body and at a second position closer to the test body than the first position. A pressure sensor;
Preparing a device comprising:
The first sound pressure sensor and the second sound are transmitted through the first probe and the second probe while radiating sound waves from the sound source toward the test body in the heated tube body. Measuring the sound pressure in the tube with a sound pressure sensor;
Measuring the temperature of the first probe and the temperature of the second probe during the measurement of the sound pressure;
A first measured sound pressure by the first sound pressure sensor via the first probe, a second measured sound pressure by the second sound pressure sensor via the second probe, the first Calculating a correction transfer function based on the measured temperature of the probe and the measured temperature of the second probe, and evaluating the normal incidence acoustic characteristics of the specimen based on the corrected transfer function;
A normal incidence acoustic characteristic measuring method including: A sound source is arranged at one end, and a tube body in which a test object to be measured is arranged in the tube,
A first sound pressure sensor having a first probe disposed at a first position between the sound source and the specimen in the tube wall of the tube body;
A second sound having a second probe disposed between the sound source and the test body in the tube wall of the tube main body and at a second position closer to the test body than the first position. A pressure sensor;
A program used for measuring normal incidence acoustic characteristics using a device including:
A first measured sound pressure by the first sound pressure sensor via the first probe, a second measured sound pressure by the second sound pressure sensor via the second probe, the first A program for causing a computer to function as a corrected transfer function calculating unit that calculates a corrected transfer function based on a measured temperature of a probe and a measured temperature of the second probe.

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