JP2006003161A - Noise measuring apparatus and noise measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noise measuring apparatus and a noise measuring method capable of reducing cost. <P>SOLUTION: The noise measuring apparatus is provided with a relation calculation means for calculating the mutual relation between a sound pressure level with respect to a predetermined sound in a half-free sound field state or free sound field state, and a sound pressure level with respect to the predetermined sound at a predetermined position being neither in a half-free sound field state nor in a free sound field state, and a correction means for correcting a sound pressure level measured at the predetermined position being neither in a half-free sound field state nor in a free sound field state, on the basis of the mutual relation calculated by the relation calculation means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a noise measuring device and a noise measuring method.

In order to compare the measured values of noise, noise measurement is performed according to the index, and as an example of measurement along this index, the intake sound at the intake port in the engine compartment of the vehicle is in a semi-free sound field state (semi-anechoic state) ). Also known is a noise measurement device that measures intake sound using chassis drum equipment that can assume the actual running state without moving the vehicle in order to create a semi-free sound field state where sound reflection is difficult to occur. (For example, refer to Patent Document 1).
JP-A-9-146443

  However, in the conventional noise measuring device, in order to create a semi-free sound field state, equipment such as a chassis drum equipment that can be assumed to actually run without moving the vehicle is required. Thereby, the cost for noise measurement increases.

  In addition, when a component around the intake port cannot be removed, the sound pressure level is increased by this component, and it is difficult to measure the intake sound in the semi-free sound field state.

  The present invention has been made to solve such problems, and it is a main object of the present invention to provide a noise measurement device and a noise measurement method that realize a reduction in cost.

  In order to achieve the above object, one aspect of the present invention includes: a sound pressure level for a predetermined sound in a semi-free sound field state or a free sound field state; A relationship calculating means for calculating a relative relationship between the sound pressure level and the sound, and a sound pressure level measured at the predetermined position that is not in the semi-free sound field state and the free sound field state; A noise measuring device comprising: a correcting unit configured to correct based on a relative relationship.

  According to this aspect, it is possible to easily perform noise measurement without requiring special equipment such as a chassis drum equipment for measuring sound in a semi-free sound field or a free sound field state. That is, the cost of the noise measuring device can be reduced.

  Further, in this aspect, the relative relationship is, for example, a sound pressure level with respect to the predetermined sound in the semi-free sound field state or the free sound field state, and the predetermined position that is not in the semi-free sound field state and the free sound field state. It is the difference or ratio with the sound pressure level for the predetermined sound.

  Furthermore, in this one aspect, the relationship calculating means performs frequency analysis on at least one speaker that generates the predetermined sound, at least one microphone that detects the predetermined sound, and sound detected from the microphone. It is preferable to include a frequency analyzer and an arithmetic unit that calculates the relative relationship based on the value analyzed by the frequency analyzer.

  One aspect of the present invention for achieving the above object is a noise measurement method for measuring vehicle noise, which measures a sound pressure level for a predetermined sound at a predetermined position that is not in a semi-free sound field state and a free sound field state. A second step of measuring a sound pressure level for the predetermined sound in a semi-free sound field state or a free sound field state, and the sound pressure level measured in the first step and the second step. A third step of calculating a difference or ratio with the measured sound pressure level, a fourth step of measuring a sound pressure level at the predetermined position during actual traveling of the vehicle, and a sound pressure measured in the fourth step. A fifth step of subtracting the difference calculated in the third step from a level, or multiplying the sound pressure level measured in the fourth step by the ratio calculated in the third step. This is a noise measurement method characterized by the following.

  In addition, the said predetermined position is an inlet port in an engine compartment, for example.

  ADVANTAGE OF THE INVENTION According to this invention, the noise measuring device and noise measuring method which implement | achieved cost reduction can be provided.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. Note that the basic concept, main hardware configuration, operating principle, basic control method, and the like of the noise measurement device are known to those skilled in the art, and thus detailed description thereof is omitted.

  FIG. 1 is a system configuration diagram of a noise measuring apparatus according to an embodiment of the present invention.

  In FIG. 1, the noise measurement apparatus 2 according to the present embodiment includes a microphone 4 that detects intake sound or the like at an intake port, and a frequency that is connected to the microphone 4 and performs frequency analysis on the sound detected by the microphone 4. And an analyzer 6. The frequency analyzer 6 is connected to a computer 8 that performs various calculations on the values analyzed by the frequency analyzer 6. Furthermore, the computer 8 is connected to one speaker 10 that generates a predetermined sound, and the speaker 10 generates a predetermined sound or the like based on a control signal from the computer 8. Although the intake sound or the like is detected by one microphone 4, the number of microphones that detect the intake sound or the like may be arbitrary. Moreover, although the predetermined sound is emitted by one speaker 10, the number of the speakers 10 that emit the predetermined sound may be arbitrary.

  The computer 8 is composed of a CPU, a RAM, a ROM, and the like, and mainly performs calculations on values transmitted from the frequency analyzer 6.

  Next, a noise measurement method using the noise measurement device will be described.

  First, the difference between the sound pressure level for a predetermined sound in the semi-free sound field state (semi-anechoic room) and the sound pressure level for the predetermined sound in the air intake in the engine compartment that is not in the semi-free sound field state is calculated. Next, the sound pressure level at the intake port in the engine compartment that is not in the semi-free sound field state during actual traveling of the vehicle is measured. Thereafter, correction is performed by subtracting the calculated difference from the measured sound pressure level, and the sound pressure level of the intake port in the engine compartment in the semi-free sound field state is calculated. As a result, it is possible to measure the intake sound in the engine compartment during actual running in a semi-free sound field state without using chassis drum equipment or the like.

  Furthermore, the noise measurement method described above will be described in detail.

  FIG. 2 is a diagram showing a flow of a noise measuring method according to an embodiment of the present invention. FIG. 3A is a diagram showing the relationship between the frequency and the sound pressure level for a predetermined sound measured in the engine compartment. FIG. 3B is a diagram showing the relationship between the frequency and the sound pressure level for a predetermined sound measured in the semi-free sound field state (semi-anechoic state). FIG. 3C is a diagram showing the relationship between the frequency and the increased sound pressure level (hereinafter referred to as the increased sound pressure level). FIG. 3D is a diagram showing the relationship between the frequency and the sound pressure level with respect to the intake sound in the engine compartment during actual traveling. FIG. 3E is a diagram showing the relationship between the frequency and the sound pressure level with respect to the intake sound during actual running in the semi-free sound field state. 3A to 3E, the vertical axis represents the sound pressure level (dB), and the horizontal axis represents the frequency (Hz). 3A and 3B are diagrams set for convenience, and FIG. 3D shows the actually measured sound pressure level.

  As shown in FIG. 2, in step 100, the microphone 4 is attached to the intake port in the engine compartment, and the speaker 10 is attached to a position away from the microphone 4 by, for example, about 10 cm. Next, the speaker 10 generates a predetermined sound based on a control signal from the computer 8. This predetermined sound is detected by the microphone 4, and the microphone 4 transmits the detected value to the frequency analyzer 6. Since the detected predetermined sound is reflected in the engine compartment, it is not in a semi-free sound field state.

  The frequency analyzer 6 performs frequency analysis on the detection value transmitted from the microphone 4, calculates the relationship between the frequency and the sound pressure level (FIG. 3A), and calculates the relationship between the calculated frequency and the sound pressure level. Send the relationship to the computer 8. For convenience, for example, the sound pressure level = A (constant).

  In step 110, the speaker 10 and the microphone 4 are installed in a semi-free sound field (semi-anechoic room), and the speaker 10 generates a predetermined sound based on a control signal from the computer 8. The predetermined sound is detected by the microphone 4 and transmitted to the frequency analyzer 6. Here, the distance between the speaker 10 and the microphone 4 is, for example, about 10 cm. The frequency analyzer 6 performs frequency analysis on the transmitted detection value, calculates the relationship between the frequency and the sound pressure level (FIG. 3B), and calculates the relationship between the calculated frequency and the sound pressure level by the computer 8. Send to. For convenience, for example, the sound pressure level = B (constant).

  In step 120, the computer 8 subtracts the sound pressure level B calculated in step 110 from the sound pressure level A calculated in step 100 at each frequency, and the relationship between the frequency and the increased sound pressure level (FIG. 3). (C)) is calculated. In this case, the increased sound pressure level is A−B = C (constant) for convenience. Here, sound reflection occurs in the engine compartment because of the closed space. Thereby, the sound pressure level of the intake sound measured in the engine compartment is increased by the above-described increased sound pressure level C as compared with the sound pressure level measured in the semi-free sound field state.

  In step 130, the microphone 4 attached to the intake port in the engine compartment detects the intake sound at the intake port in the engine compartment when the vehicle actually travels, and the detected value is transmitted to the frequency analyzer 6. Since the detected intake sound is reflected in the engine compartment, it is not in a semi-free sound field state. The frequency analyzer 6 performs frequency analysis on the transmitted detection value, calculates a relationship between the frequency and the sound pressure level (FIG. 3D), and calculates the relationship between the calculated frequency and the sound pressure level by the computer 8. Send to.

  In step 140, the computer 8 increases the convenience calculated in step 120 from the sound pressure level during actual driving (broken line in FIG. 3E) that is not in the semi-free sound field state calculated in step 130 at each frequency. The subtracted sound pressure level C is subtracted to calculate the relationship between the actual traveling frequency and sound pressure level (solid line in FIG. 3E) in the semi-free sound field state.

  As described above, it is possible to measure the intake sound in the engine compartment during actual driving in the semi-free sound field state, so this measurement result is compared with the intake sound of other vehicles measured in the semi-free sound field state. Can be used. This increases the usefulness of the measured data. For example, the intake sound in the measured semi-free sound field state can be used as an index of the intake sound for the vehicle to be developed next.

  In addition, it is possible to measure the intake sound in the engine compartment during actual driving in a semi-free sound field state without using chassis drum equipment or the like. As a result, it is possible to provide a noise measurement device and a noise measurement method that achieve cost reduction.

  Although a preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications and substitutions can be made to the above-described embodiment without departing from the scope of the present invention. Can be added.

  For example, although the sound pressure level in the semi-free sound field is measured in the above-described embodiment, the sound pressure level in the free sound field may be measured.

  In step 110, the speaker 10 and the microphone 4 are installed in a semi-free sound field (semi-anechoic chamber), and a predetermined sound is detected by the microphone 4. The predetermined sound may be detected by attaching 10 to the position about 10 cm from the microphone 4 so that no sound is reflected near the air inlet. For example, the hood is removed from the vehicle, the air intake is pulled out of the vehicle so that no sound is reflected near the air intake, and the extracted air intake is fixed at a predetermined position outside the vehicle. The predetermined sound may be detected in a low state.

  Furthermore, although the intake sound at the intake port in the engine compartment is measured in the above-described embodiment, when the gap between the body and the sounding body is narrow, for example, the radiated sound of a transmission or a muffler may be measured. It is only necessary to measure sound in a place where sound is easily reflected in a closed space.

  In step 120, the computer 8 subtracts the sound pressure level B calculated in step 110 from the sound pressure level A calculated in step 100. A ratio with the calculated sound pressure level B may be calculated. In this case, in step 140, the computer 8 multiplies the sound pressure level during actual traveling in the semi-free sound field state calculated in step 130 by the ratio calculated in step 120, and during actual traveling in the semi-free sound field state. The relationship between the frequency and the sound pressure level is calculated.

  The present invention can be used for a vehicle noise measurement device and a noise measurement method. The appearance, weight, size, running performance, etc. of the vehicle to be measured are not limited.

1 is a system configuration diagram of a noise measurement device according to an embodiment of the present invention. It is a figure which shows the flow of the noise measuring method which concerns on one Example of this invention. (A) It is a figure which shows the relationship between the frequency and sound pressure level about the predetermined sound measured within the engine compartment. (B) It is a figure which shows the relationship between the frequency and sound pressure level about the predetermined sound measured in the semi-free sound field state. (C) It is a figure which shows the relationship between a frequency and an increase sound pressure level. (D) It is a figure which shows the relationship between the frequency with respect to the intake sound in the engine compartment at the time of real driving | running | working, and a sound pressure level. (E) It is a figure which shows the relationship between the frequency with respect to the intake sound at the time of actual driving | running | working in a semi-free sound field state, and a sound pressure level.

Explanation of symbols

2 Noise measurement device 4 Microphone 6 Frequency analyzer 8 Computer 10 Speaker

Claims (5)

Calculation of a relationship for calculating a relative relationship between a sound pressure level with respect to a predetermined sound in a semi-free sound field state or a free sound field state and a sound pressure level with respect to the predetermined sound at a predetermined position not in the semi-free sound field state and the free sound field state Means,
Correction means for correcting the sound pressure level measured at the predetermined position not in the semi-free sound field state and the free sound field state based on the relative relationship calculated by the relationship calculation unit, A noise measuring device. The noise measuring device according to claim 1,
The relative relationship is as follows: a sound pressure level with respect to the predetermined sound in a semi-free sound field state or a free sound field state, and a sound pressure level with respect to the predetermined sound in the predetermined position that is not in the semi-free sound field state and the free sound field state. A noise measuring device characterized by being a difference or a ratio. The noise measuring device according to claim 1 or 2,
The relationship calculating means includes
At least one speaker for generating the predetermined sound;
At least one microphone for detecting the predetermined sound;
A frequency analyzer for performing frequency analysis on the sound detected from the microphone;
A noise measuring device comprising: an arithmetic unit that calculates the relative relationship based on a value analyzed by the frequency analyzer. A noise measurement method for measuring vehicle noise,
A first step of measuring a sound pressure level for a predetermined sound at a predetermined position that is not in the semi-free sound field state and the free sound field state;
A second step of measuring a sound pressure level for the predetermined sound in a semi-free sound field state or a free sound field state;
A third step of calculating a difference or ratio between the sound pressure level measured in the first step and the sound pressure level measured in the second step;
A fourth step of measuring a sound pressure level at the predetermined position during actual traveling of the vehicle;
The difference calculated in the third step is subtracted from the sound pressure level measured in the fourth step, or the ratio calculated in the third step is subtracted from the sound pressure level measured in the fourth step. A noise measurement method comprising: a fifth step of multiplying. The noise measurement method according to claim 4,
The noise measuring method according to claim 1, wherein the predetermined position is an intake port in an engine compartment.

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