JP2014085439A - Impulse response measurement system and impulse response measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure an impulse response having a high S/N ratio in a shorter time than before.SOLUTION: An impulse response measurement system includes: a reproduction device having a speaker and a reproduction control part; and a measurement device having a microphone and an impulse response calculation part. The reproduction control part reproduces a part of a measurement signal from the speaker by excluding first time since the measurement signal starts until the frequency of the measurement signal reaches the reproduction frequency band of the speaker or the recording frequency band of the microphone and second time since the frequency of the measurement signal exceeds the reproduction frequency band of the speaker or the recording frequency band of the microphone until the measurement signal ends. The microphone records the response to the time of a part of the measurement signal under consideration of time based on the reverberation characteristics of the measurement space, and the impulse response calculation part calculates the impulse response from the response and the inverse signal of the measurement signal.

Description

  The present invention relates to an impulse response measurement system and measurement method.

  In the field of room acoustics, impulse responses are often measured in order to calculate various acoustophysical indices of the room (for example, Non-Patent Document 1). In principle, it is sufficient to measure the output when an impulse is directly input to the system. However, since the energy of the impulse itself is small (it is difficult to generate an impulse with a large volume), a high S / N ratio is ensured. Is difficult. Therefore, a Swept-Sine method using a signal obtained by extending an impulse on the time axis as a measurement signal is widely used (for example, Non-Patent Document 2).

  In the measurement of the impulse response by the Swept-Sine method, a higher S / N ratio can be ensured by increasing the length of the measurement signal. For example, in the case of a linear and time-invariant system, if the length of the measurement signal is doubled, the S / N ratio is improved by +3 dB. In particular, in a space where sound insulation design is not sufficiently performed, it is important to ensure a high S / N ratio by emitting a measurement signal as long as possible when measuring the impulse response.

  A conventional impulse response measurement technique will be described with reference to FIGS. For example, in the measurement space shown in FIG. 4, a measurement signal A (TSP (Time Stretched Pulse) signal) having a length T1 shown in FIG. 5 is reproduced from a speaker. Here, in order to ensure a high S / N ratio, T1 is set sufficiently long. Then, the response B having the same length T1 is recorded by the microphone, and the impulse response is calculated by convolving the response B with the inverse signal of the measurement signal A. In this case, the measurement time takes T1.

Fumiaki Sato “Measuring technique of room acoustic impulse response” Journal of the Acoustical Society of Japan, Vol.58 No.10 (2002), pp.669-676 Fumiaki Sato "Sound Propagation Measurement Based on Swept-Sine Method" Journal of the Acoustical Society of Japan, Vol.63, No.6 (2007), pp.322-327

  In the conventional method, the longer the signal length is in order to ensure the S / N ratio, the longer the time required for measurement. In particular, when a large number of impulse responses are measured within a limited time, the signal length cannot be sufficiently increased, and a high S / N ratio may not be ensured. In addition, when a disturbance such as sudden noise occurs even once during measurement, there is a problem that measurement using a long signal must be performed again from the beginning.

  Therefore, an object of the present invention made in view of such a point is to provide an impulse response measurement system capable of measuring an impulse response in a shorter time than before without impairing the S / N ratio.

  In order to solve the above-described problems, an impulse response measurement system according to the present invention includes a speaker that reproduces a measurement signal whose frequency increases or decreases in one direction with time, and a reproduction control that controls reproduction of the measurement signal. An impulse response measurement system comprising: a playback device including: a microphone; a microphone that records a response of the measurement signal; and an impulse response calculation unit that calculates an impulse response of a measurement space from the response. The reproduction control unit includes a first time from the beginning of the measurement signal until the frequency of the measurement signal reaches the reproduction frequency band of the speaker or the recording frequency band of the microphone, and the frequency of the measurement signal is reproduced by the speaker. A second period from the time when the frequency band or the recording frequency band of the microphone is exceeded until the end of the measurement signal. A part of the measurement signal is reproduced from the speaker, and the microphone records the response by adding a time based on a reverberation characteristic of the measurement space to a part of the time of the measurement signal. Then, the impulse response calculation unit calculates the impulse response from the response and an inverse signal of the measurement signal.

  In addition, the reproduction control unit includes the first time from the beginning of the measurement signal until the frequency of the measurement signal reaches the reproduction frequency band of the speaker, and the frequency of the measurement signal satisfies the reproduction frequency band of the speaker. It is preferable that a part of the measurement signal is reproduced from the speaker except for the second time from when the measurement signal is exceeded to the end of the measurement signal.

  In addition, the reproduction control unit may perform the first time from the beginning of the measurement signal until the frequency of the measurement signal reaches the recording frequency band of the microphone, and the frequency of the measurement signal corresponds to the recording frequency band of the microphone. It is preferable that a part of the measurement signal is reproduced from the speaker except for the second time from when the measurement signal is exceeded to the end of the measurement signal.

  In order to solve the above-described problems, an impulse response measurement method according to the present invention controls a speaker that reproduces a measurement signal whose frequency increases or decreases in one direction with time, and controls the reproduction of the measurement signal. In an impulse response measurement system comprising: a playback device including a playback control unit; a measurement device including a microphone that records a response of the measurement signal; and an impulse response calculation unit that calculates an impulse response of a measurement space from the response. In the impulse response measurement method, the reproduction control unit has a first time from the beginning of the measurement signal until the frequency of the measurement signal reaches the reproduction frequency band of the speaker or the recording frequency band of the microphone, and Does the frequency of the measurement signal exceed the playback frequency band of the speaker or the recording frequency band of the microphone? Replaying a portion of the measurement signal from the speaker, except for a second time until the end of the measurement signal; and the microphone reverberates in the measurement space at a portion of the measurement signal. Recording the response in consideration of time based on characteristics, and the step of calculating the impulse response from the response and an inverse signal of the measurement signal by the impulse response calculation unit. Method.

  According to the impulse response measurement system and the impulse response measurement method according to the present invention, it is possible to measure the impulse response in a shorter time than before without impairing the S / N ratio.

It is a figure which shows the structure of the impulse response measuring system which concerns on one Embodiment of this invention. It is a figure which shows the flow of the impulse response calculation concerning this invention. It is a figure which shows the example which cuts out the signal of the reproduction | regeneration frequency band of a speaker from a measurement signal. It is a figure which shows an example of the measurement space of an impulse response. It is a figure which shows the measurement of the impulse response using the conventional measurement signal.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an impulse response measurement system according to an embodiment of the present invention. The impulse response measurement system includes a reproduction device 10 that reproduces a measurement signal for impulse response measurement, and a measurement device 20 that records the measurement signal and calculates an impulse response of the measurement space.

  The reproduction apparatus 10 includes a speaker SP that reproduces a measurement signal whose frequency increases or decreases in one direction with time, a reproduction control unit 11 that controls reproduction of the measurement signal, and a measurement signal storage unit 12 that stores the measurement signal. With. The measurement signal in the present embodiment is, for example, a TSP signal obtained by extending an impulse whose frequency increases with time on the time axis (a frequency of a sine wave is swept), but is not limited thereto.

  The measurement device 20 includes a microphone MC that records the response of the measurement signal from the playback device 10, an impulse response calculation unit 21 that calculates the impulse response of the measurement space from the recorded response, and calculation of the calculated impulse response and impulse response. And a storage unit 22 for storing an inverse signal of the measurement signal to be used.

  FIG. 2 is a diagram showing a flow of calculation of an impulse response according to the present invention. First, in the reproduction apparatus 10, the reproduction control unit 11 reads the measurement signal A having the length T1 from the measurement signal storage unit 12 (FIG. 2A). Here, the reproduction control unit 11 removes the section of the measurement signal A from time Tf from the beginning and time Tb from the end, as shown in FIG. 2B, the reproduction frequency band of the speaker SP of the reproduction apparatus 10 or the measurement apparatus. The measurement signal a having a length T2 including the recording frequency band of the 20 microphones MC is cut out, and the measurement signal a is reproduced from the speaker SP. The time Tf and the time Tb will be described later.

  In the measuring apparatus 20, the microphone MC has a response of length T2 + α in which the time α determined from the reverberation characteristics of the measurement space (α ≧ impulse response length-1 of the measurement space) is added to the length (time) T2 of the measurement signal a. b 'is recorded (FIG. 2 (c)). As the time α, a value measured in advance in each measurement space can be used, or a predetermined value based on the shape and size of the measurement space can be used. In order to match the length of the response b ′ and the measurement signal A, the impulse response calculation unit 21 pads the time Tf before the response b ′ and the time Tb−α after the response b ′ with 0, A response B ′ having the same length T1 as the measurement signal A is created (FIG. 2D). The impulse response calculation unit 21 can calculate the impulse response by convolving the inverse signal A ′ of the measurement signal A with the response B ′.

  FIG. 3 is a diagram showing the relationship between the measurement signal a extracted from the measurement signal A by the reproduction control unit 11 and the reproduction frequency band of the speaker SP. The reproduction control unit 11 has a time Tf from the beginning of the measurement signal A until the frequency of the measurement signal A reaches the reproduction frequency band (lower limit) of the speaker SP, and the frequency of the measurement signal A is the reproduction frequency band (upper limit) of the speaker SP. The measurement signal a having a length T2, which is a part of the measurement signal A, is cut out except for the time Tb from when the measurement signal A is exceeded to the end of the measurement signal A. The measurement signal a is slightly wider than the reproduction frequency band of the speaker SP, thereby covering the reproduction frequency band of the speaker SP and in a time shorter than the length T1 of the original measurement signal A. Measurements can be made.

  The reproduction control unit 11 can extract the measurement signal a from the measurement signal A based on the recording frequency band of the microphone MC of the measurement device 20 by the same processing as in FIG. In this case, the reproduction control unit 11 determines the time Tf from the beginning of the measurement signal A until the frequency of the measurement signal A reaches the recording frequency band (lower limit) of the microphone MC, and the frequency of the measurement signal A is the recording frequency band of the microphone MC. The measurement signal a having a length T2, which is a part of the measurement signal A, is cut out except for the time Tb from exceeding (upper limit) to the end of the measurement signal A. It should be noted that the frequency band of the measurement signal a is slightly wider than the recording frequency band of the microphone MC, thereby covering the recording frequency band of the microphone MC and in a time shorter than the length T1 of the original measurement signal A. Measurements can be made.

  Further, the reproduction control unit 11 can extract the measurement signal a from the measurement signal A so that both the reproduction frequency band of the speaker SP of the reproduction apparatus 10 and the recording frequency band of the microphone MC of the measurement apparatus 20 are included. . In this case, the reproduction control unit 11 measures the time Tf from the beginning of the measurement signal A until the frequency of the measurement signal A reaches the lower one of the lower limit of the reproduction frequency band of the speaker SP or the recording frequency band of the microphone MC, and the measurement signal A. Of the length T2, which is a part of the measurement signal A, except for the time Tb from the time when the frequency exceeds the upper limit of the reproduction frequency of the speaker SP or the recording frequency band of the microphone MC until the end of the measurement signal A Cut out the measurement signal a. Note that the frequency band of the measurement signal a is slightly wider than the reproduction frequency band of the speaker SP and the recording frequency band of the microphone MC, thereby covering the reproduction frequency band of the speaker SP and the recording frequency band of the microphone MC, and Measurement can be performed in a time shorter than the length T1 of the original measurement signal A.

  Thus, according to the present embodiment, the reproduction control unit 11 performs the first time from the beginning of the measurement signal A until the frequency of the measurement signal A reaches the reproduction frequency band of the speaker SP or the recording frequency band of the microphone MC. Except for Tf and the second time Tb from when the frequency of the measurement signal A exceeds the reproduction frequency band of the speaker SP or the recording frequency band of the microphone MC until the end of the measurement signal A, A certain measurement signal a is reproduced from the speaker SP, and the microphone MC records the response b ′ by adding the time α based on the reverberation characteristics of the measurement space to the time of the measurement signal a, and the impulse response calculation unit 21 The impulse response of the measurement space is calculated from b ′ and the inverse signal of the measurement signal A. Thus, by cutting out and reproducing only a relatively short part including the reproduction frequency band of the speaker SP used for measurement or the recording frequency band of the microphone MC from the original measurement signal A, the S / N ratio is impaired. In addition, the impulse response can be measured and calculated in a shorter time than in the past. Further, since the microphone MC records the response b ′ in consideration of not only the time of the cut out measurement signal a but also the time α based on the reverberation characteristic of the measurement space, the microphone MC has a shorter time and a characteristic of the measurement space. It is possible to obtain a matched impulse response.

  The reproduction control unit 11 can reproduce the measurement signal a, which is a part of the measurement signal A, from the speaker SP based on either the reproduction frequency band of the speaker SP or the recording frequency band of the microphone MC. Thereby, the impulse response can be measured in a time shorter than the length T1 of the original measurement signal A, covering the reproduction frequency band of the speaker SP or the recording frequency band of the microphone MC.

  Further, the reproduction control unit 11 can reproduce the measurement signal a, which is a part of the measurement signal A, from the speaker SP so as to include both the reproduction frequency band of the speaker SP and the recording frequency band of the microphone MC. Thereby, it is possible to measure the impulse response in a time shorter than the length T1 of the original measurement signal A while covering the reproduction frequency band of the speaker SP and the recording frequency band of the microphone MC.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, functions included in each component can be rearranged so as not to be logically contradictory, and a plurality of components can be combined into one or divided.

  In the above embodiment, a TSP signal whose frequency increases with time is assumed as the measurement signal, but a signal whose frequency decreases with time can also be used as the measurement signal. In this case, the reproduction control unit 11 determines that the time Tf from the beginning of the measurement signal A until the frequency of the measurement signal A reaches the upper limit of the reproduction frequency band of the speaker SP or the recording frequency band of the microphone MC and the frequency of the measurement signal A A measurement signal a having a length T2, which is a part of the measurement signal A, is cut out except for a time Tb from when the lower limit of the reproduction frequency band of the speaker SP or the recording frequency band of the microphone MC is exceeded. be able to.

  Furthermore, in the present invention, a logarithmic TSP signal (a signal obtained by sweeping the frequency of a sine wave at a constant speed on a logarithmic axis) or the like, the frequency continuously increases and decreases with time and is recorded. Needless to say, any measurement signal can be applied as long as the impulse response can be calculated by convolution of the response and the inverse signal of the measurement signal.

  According to the present invention, there is a usefulness that an impulse response with a high S / N ratio can be measured in a shorter time than before.

DESCRIPTION OF SYMBOLS 10 Playback apparatus 11 Playback control part 12 Measurement signal memory | storage part SP Speaker 20 Measuring apparatus 21 Impulse response calculation part 22 Storage part MC Microphone

Claims (4)

A speaker that reproduces a measurement signal whose frequency increases or decreases in one direction with time, a reproduction device that controls reproduction of the measurement signal, a microphone that records a response of the measurement signal, and In an impulse response measurement system comprising: a measurement device comprising an impulse response calculation unit that calculates an impulse response of a measurement space from the response.
The reproduction control unit includes a first time from the beginning of the measurement signal until the frequency of the measurement signal reaches the reproduction frequency band of the speaker or the recording frequency band of the microphone, and the frequency of the measurement signal is the frequency of the speaker. A part of the measurement signal is reproduced from the speaker except for a second time from the time when the reproduction frequency band or the recording frequency band of the microphone is exceeded until the end of the measurement signal.
The microphone records the response by adding a time based on a reverberation characteristic of the measurement space to a part of the time of the measurement signal,
The impulse response calculation system, wherein the impulse response calculation unit calculates the impulse response from the response and an inverse signal of the measurement signal.   The reproduction control unit includes the first time from the beginning of the measurement signal until the frequency of the measurement signal reaches the reproduction frequency band of the speaker, and the frequency of the measurement signal exceeds the reproduction frequency band of the speaker. 2. The impulse response measurement system according to claim 1, wherein a part of the measurement signal is reproduced from the speaker except for the second time from the first to the end of the measurement signal.   The reproduction control unit includes the first time from the beginning of the measurement signal until the frequency of the measurement signal reaches the recording frequency band of the microphone, and the frequency of the measurement signal exceeds the recording frequency band of the microphone. 2. The impulse response measurement system according to claim 1, wherein a part of the measurement signal is reproduced from the speaker except for the second time from the first to the end of the measurement signal. A speaker that reproduces a measurement signal whose frequency increases or decreases in one direction with time, a reproduction device that controls reproduction of the measurement signal, a microphone that records a response of the measurement signal, and An impulse response measurement method in an impulse response measurement system, comprising: a measurement device including an impulse response calculation unit that calculates an impulse response of a measurement space from the response,
The reproduction control unit has a first time from the beginning of the measurement signal until the frequency of the measurement signal reaches the reproduction frequency band of the speaker or the recording frequency band of the microphone, and the frequency of the measurement signal is the frequency of the speaker. Replaying a part of the measurement signal from the speaker, except for a second time from the time when the reproduction frequency band or the recording frequency band of the microphone is exceeded until the end of the measurement signal;
The microphone records the response by adding a time based on a reverberation characteristic of the measurement space to a part of the time of the measurement signal;
The impulse response measurement method, wherein the impulse response calculation unit includes a step of calculating the impulse response from the response and an inverse signal of the measurement signal.