JP2010136027A - Acoustic measurement system and acoustic recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure acoustic characteristics in a specified space using a plurality of microphones by considering changes of microphone positions when recording acoustic characteristics of a playback system or changes of ear positions of listeners when reproducing acoustic characteristics of an original sound field in the playback system. <P>SOLUTION: An acoustic recording device 1 has a projecting base 3 which secures a specified closed space 8 which projects from a head side 6 based on a dummy head placed at a measurement target position in an acoustic space or the position of a listener's ear 2, and a plurality of microphones 10 which are arranged on the outer surface 9 of the projecting base 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an acoustic measurement system and an acoustic recording apparatus, and more specifically, by measuring an acoustic signal output from a speaker installed in a specific acoustic space with a plurality of microphones, from each speaker in the acoustic space. The present invention relates to an acoustic measurement system and an acoustic recording apparatus that measure acoustic characteristics of each microphone.

  Conventionally, there has been proposed a sound field reproduction method for recording (measuring) the acoustic characteristics of a certain space (original sound field) and then virtually reproducing the acoustic characteristics of the original sound field measured in a space different from the space. As a method for spatially reproducing a sound field, for example, a boundary sound field control method based on multichannel-multipoint control (for example, Patent Document 1) is known.

  In the method disclosed in Patent Document 1 or the like, a sound field reproduction filter for reproducing a sound field is calculated based on the acoustic characteristics recorded in the original sound field, and a sound source convolution calculation process is performed using the calculated sound field reproduction filter. By performing (for example, a convolution calculation process using an FIR filter), the original sound field is virtually reproduced in a different space. A detailed method for calculating the filter is disclosed in Patent Document 2 and the like. By using such a sound field reproduction method, it is possible for the listener to obtain a feeling as if listening in the original sound field in different spaces.

  On the other hand, even when the above-described method is used, it is not easy to obtain good reproduction accuracy for the entire audio band.

  For example, when reproducing a sound field, it is necessary to record a sound field (original sound field) to be reproduced and an acoustic characteristic of a reproduction system (reproduction sound field) for reproduction. When recording acoustic characteristics in this way, a dummy head is placed at the listening position in order to obtain acoustic characteristics that conform to the sound that the listener (human) actually listens to, and the dummy head (HATS (Head And A method of recording sound (for example, impulse input sound) output in a reproduction environment is provided by providing a microphone near the earlobe (including Torso Simulator).

Further, a method of measuring acoustic characteristics in consideration of the state of sound transmission in the ear hole by forming an earlobe and an ear hole on the dummy head in the same manner as a human and installing a microphone in the back of the ear hole is also used. In this way, by installing the microphone in the ear portion of the dummy head and recording the acoustic characteristics, it is possible to acquire the same acoustic characteristics as when the listener is actually located at that location.
JP 2008-118559 A Japanese Patent Laid-Open No. 2005-249989

  However, the microphone installed in the ear part of the dummy head is often locally installed in the back of the ear hole or in the vicinity of the earlobe. For this reason, when reproducing the acoustic characteristics of the original sound field by the reproduction system, there is a problem that good reproduction accuracy cannot be obtained if the listener's ear position deviates greatly from the microphone position. Moreover, since the position of the microphone is local, the listening point is almost a “point”. For this reason, if there is a gap between the microphone position when recording the acoustic characteristics of the playback system and the ear position when the listener actually listens to the sound in the reproduced sound field, the effect of the position gap will be affected. There was a problem of appearing prominently.

  In order to reduce the influence of such microphone misalignment, the method disclosed in Patent Document 1 measures the sound field environment by arranging a plurality of microphones so as to cover the head of the dummy head. A wide range of methods has been proposed. By thus installing a plurality of microphones so as to cover the head, it is possible to realize a good sound field reproduction over a wide range. However, in this method, it is necessary to install an infinite number of microphones so as to cover the periphery of the head, and in order to reproduce the entire audio band well, it is necessary to closely arrange a plurality of microphones. There was a problem that it was not easy to use in reality.

  The present invention has been made in view of the above problems, and fluctuations in the microphone position when recording the acoustic characteristics of the reproduction system, or fluctuations in the listener's ear position when reproducing the acoustic characteristics of the original sound field in the reproduction system. In view of the above, it is an object to provide an acoustic measurement system and an acoustic recording apparatus capable of measuring acoustic characteristics in a specific space using a large number of microphones.

  In order to solve the above-described problem, an acoustic measurement system according to the present invention records an acoustic signal output from a plurality of speakers installed in a specific acoustic space with a plurality of microphones, so that each speaker in the acoustic space is recorded. A sound measurement system for measuring sound characteristics from the microphone to each microphone, wherein the dummy head or the head of the listener is set based on the position of the ear of the dummy head or the listener installed at the measurement target position in the acoustic space. An acoustic recording device having a tufting base that can secure a certain closed space that is tufted from the side, and the plurality of microphones disposed on the outer surface of the tufting base, and the measurement target position in the acoustic space An imaging device for imaging the dummy head or the head of the listener installed on the head, and the state of the head imaged by the imaging device at the position to be measured. Characterized in that it comprises a display device that visibly displayed.

  In addition, the sound recording apparatus according to the present invention records sound signals output from speakers installed in a specific sound space with a plurality of microphones, so that sound characteristics from each speaker to each microphone in the sound space can be obtained. A sound recording apparatus for measuring, wherein the dummy head installed at the measurement target position in the acoustic space or a certain closed position raised from the side of the head of the listener based on the position of the listener's ear It is characterized by having a tuft base that can secure a space and the plurality of microphones arranged on the outer surface of the tuft base.

  In the acoustic measurement system and the acoustic recording apparatus according to the present invention, the microphone constituting the acoustic recording apparatus secures a certain closed space raised from the dummy head or the listener's head side surface with reference to the ear position of the listener. Arranged on the outer surface of the possible bunching base. For this reason, when the acoustic characteristics in a specific acoustic space are measured using the acoustic measurement system and the acoustic recording device according to the present invention, at a plurality of microphone positions arranged three-dimensionally on the outer surface of the tufted base. By controlling the sound field using this microphone position as a control point, the entire closed space surrounded by the side of the head and the buttock base becomes a substantial control area. It is possible to determine that the acoustic characteristics of are equivalent to the original sound field.

  Accordingly, it is possible to acquire a wide range of acoustic characteristics as control points compared to the case where a single microphone is installed at the ear position of the dummy head as in the conventional case, and to cover the entire head as in the conventional case. As compared with a method of measuring a wide range of acoustic characteristics around the head by arranging a microphone, it is possible to calculate acoustic characteristics in a predetermined range by an easier and more realistic method.

  Furthermore, since a certain range of acoustic characteristics that constitute the closed space can be obtained, individual differences due to the type of dummy heads and the case where the acoustic characteristics are measured using a dummy head or a direct listener as in the past It is possible to obtain acoustic characteristics that are not easily influenced by individual differences (individual differences) due to the ear shape of the listener.

  In addition, the acoustic measurement system according to the present invention includes an imaging device that images a dummy head or a listener's head, and a display device that displays the state of the imaged head so as to be visible at a measurement target position. Therefore, when the sound signal output from the speaker is recorded by the microphone using the sound recording device, the head position, that is, the installation position of the sound recording device can be confirmed. For this reason, it can suppress that a microphone position changes greatly, and it becomes possible to suppress the fall of the precision of the acoustic characteristic accompanying the fluctuation | variation of a microphone position.

  Furthermore, by suppressing the fluctuation of the microphone position and improving the accuracy of the acoustic characteristics at the measurement target position, it is possible to improve the reproduction accuracy of the reproduction target position when reproducing the acoustic characteristics of the original sound field in the reproduction system.

  Further, the acoustic measurement system described above uses the acoustic measurement system to measure the acoustic characteristics of the acoustic space in the reproduction system, thereby obtaining the acoustic characteristics of the reproduction system and the acoustic characteristics measured in the acoustic space of the original sound field. And when the sound field reproduction filter for reproducing the acoustic environment of the original sound field is calculated in the reproduction system, the reproduction system has a plurality of speakers for outputting an acoustic signal. The speaker of the reproduction system corresponds to the input direction of the acoustic signal relative to the microphone position at which the acoustic characteristics are measured in the original sound field and the direction of the high sound pressure level of the input acoustic signal. It may be arranged in a direction based on the measurement target position.

  As described above, in the acoustic measurement system according to the present invention, the plurality of speakers installed in the reproduction system includes the input direction of the acoustic signal and the high sound pressure level based on the microphone position at which the acoustic characteristics are measured in the original sound field. The input direction of the acoustic signal in the original sound field and the direction of the high sound pressure level of the input acoustic signal are reproduced with higher accuracy in the playback system. It becomes possible to do. For this reason, the output environment and output state of the acoustic signal in the reproduced sound field can be brought close to the output environment and output state of the acoustic signal in the original sound field, and the improvement of the sound reproducibility such as localization in the original sound field can be improved. It can be realized in the field.

  Furthermore, in the acoustic measurement system described above, the upper limit of the distance between the plurality of microphones disposed on the outer surface of the attraction base and the adjacent microphones is the measurement target of the acoustic signal recorded by the microphone. It may be set so as to have an interval of ½ wavelength or less of the frequency.

  As described above, in the acoustic measurement system according to the present invention, the interval between other adjacent microphones is set to an interval equal to or less than ½ wavelength of the upper limit frequency to be measured. It is possible to reliably obtain the acoustic characteristics of the frequency band. For this reason, for example, by defining the interval between adjacent microphones to an interval of about 0.85 cm or less, which is a half wavelength of a 20 kHz sound that is the upper limit frequency that can be heard by humans, It is possible to measure acoustic characteristics corresponding to the frequency band.

  According to the acoustic measurement system and the acoustic recording apparatus according to the present invention, the microphone constituting the acoustic recording apparatus is a constant closed space raised from the dummy head or the listener's head side surface with reference to the ear position of the listener. Because it is arranged on the outer surface of the bunch base that can secure the sound, it is possible to obtain the acoustic characteristics at a plurality of three-dimensionally arranged microphone positions, and the sound field is controlled using these microphone positions as control points. By doing so, the entire closed space surrounded by the head side surface and the buttock base becomes a substantial control area, and it is possible to determine that the acoustic characteristics in the closed space are equivalent to the original sound field.

  For this reason, it is possible to acquire a wide range of acoustic characteristics as control points as compared with the conventional case where a single microphone is installed at the ear position of the dummy head, and the entire head is covered as in the conventional case. In this way, it is possible to calculate the acoustic characteristics within a predetermined range by an easier and more realistic method as compared with the method of measuring a wide range of acoustic characteristics around the head by arranging the microphone.

  Furthermore, since a certain range of acoustic characteristics that constitute the closed space can be obtained, individual differences due to the type of dummy heads and the case where the acoustic characteristics are measured using a dummy head or a direct listener as in the past It is possible to obtain acoustic characteristics that are not easily influenced by individual differences (individual differences) due to the ear shape of the listener.

  Hereinafter, an acoustic measurement system and an acoustic recording apparatus according to the present invention will be described in detail with reference to the drawings. In the acoustic measurement system according to the present embodiment, the boundary sound field control method is used as the sound field reproduction method. The boundary sound field control method is that when listening to the output sound in the reproduced sound field, multiple control points (microphones) are installed near the ear position of the listener, and the characteristics of the original sound field are reproduced at this control point. In this way, the sound field is controlled so that the original sound field is perceptually perceived. In order to realize the installation of the microphone, an acoustic recording apparatus having a headphone structure is used in the acoustic measurement system according to the present invention.

[Configuration of sound recording device]
FIG. 1A is a side view showing the sound recording apparatus according to the present embodiment, FIG. 1B is a front view showing the sound recording apparatus, and FIG. It is sectional drawing which showed the AA cross section in 1 (b).

  As shown in FIGS. 1 (a) to 1 (c), the sound recording device 1 includes a base portion (boiling base portion) 3 that is formed in a substantially hemispherical shape so as to cover the ear 2, and a left and right side. And the arch portion 4 for connecting the base portions 3 and 3 of the headphone, and has the same structure as a general headphone. A recess 5 is formed inside the base 3 so that the ear 2 can be accommodated. By enclosing the ear 2 in the recess 5, the head side surface (side face) 6 and the outer surface of the base 3 are provided. 9, a closed space 8 covering the ear 2 can be secured.

  A plurality of microphones (microphone elements) 10 are arranged on the outer surface 9 of the base 3. Since the base 3 is formed in a substantially hemispherical shape, the outer surface 9 is constituted by a three-dimensional curved surface. The microphones 10 are three-dimensionally arranged M / 2 (M in total, left and right) along the three-dimensional curved surface, and the distance between the adjacent microphones 10 is 0.8 cm or less. It is installed to keep the distance of The number of microphones 10 (M) is determined by the width of the outer surface 9 because the distance between the microphones 10 is set to 0.8 cm or less.

  Note that the upper limit frequency of a sound that can be heard by humans is said to be up to about 20 kHz, and the half wavelength of this sound is about 0.85 cm. In the sound recording apparatus 1 according to the present embodiment, since the interval between adjacent microphones 10 is defined to be 0.8 cm or less, sound in a frequency band of 20 Hz to 20 kHz, which is a frequency band of sound that can be heard by humans, is recorded. It becomes possible to do. In addition, when recording a sound in a higher frequency band, it is possible to record a sound including the upper limit frequency by arranging the microphones 10 at intervals of at least 1/2 or less of the wavelength of the upper limit frequency. It becomes.

  As shown in FIG. 1, by providing a plurality of microphones 10 on the outer surface 9 of the base 3, it is possible to ensure a control point of acoustic characteristics with reference to the three-dimensional installation position of each microphone 10. Thus, by ensuring the three-dimensional control points densely, the sound field can be faithfully reproduced at the control points on the outer surface 9.

  Further, if the characteristics of the original sound field are faithfully reproduced at the control points on the outer surface 9, the sound field of the closed space 8 surrounded by the head side surface (side surface of the face) 6 and the outer surface 9 of the base 3 will be described. Can be considered equivalent to the original sound field. For this reason, as shown in FIG.1 (c), the closed space 8 enclosed by the head side surface 6 and the outer surface 9 of the base 3 can be made into a substantially controllable area, and the acoustic characteristic of an original sound field Even if the listener's ear position is moved in the reproduction environment, the acoustic characteristics of the original sound field can be faithfully reproduced if the movement range of the ear position is within the closed space 8.

  Furthermore, by using the sound recording device 1 according to the present embodiment, the sound field can be measured in a state where the ear is covered (a state where the ear is located in the closed space 8). Therefore, it is possible to minimize the influence of individual differences (individual differences) such as the dummy head and the listener's ear position and ear shape in the recording work of the sound field characteristics.

  Next, a process for measuring the acoustic characteristics of the original sound field and a process for measuring the acoustic characteristics in the reproduction system using the acoustic recording apparatus 1 according to the present embodiment will be described, and further obtained from the measured acoustic characteristics. A process for reproducing the acoustic environment of the original sound field in the reproduction system using the sound field reproduction filter will be described.

[Measurement of acoustic characteristics in the original sound field]
FIG. 2 is a diagram showing a schematic configuration of an original sound field measurement system for measuring acoustic characteristics in an acoustic space (original sound field) desired to be reproduced.

  As shown in FIG. 2, the original sound field measurement system 20 includes a speaker unit 22 installed in an acoustic space (original sound field) 21 desired to be reproduced, a sound output device 23 that outputs sound to the speaker unit 22, and a sound. Sound is collected by the computer 24 that outputs the evaluation sound to the output device 23, the dummy head D installed in the original sound field 21, the acoustic recording device 1 attached to the dummy head D, and the microphone 10 of the acoustic recording device 1. And a voice input device 26 for inputting the recorded sound.

  In the present embodiment, the acoustic environment in the passenger compartment is used as an example of the original sound field 21. Thus, by using the vehicle interior space as the original sound field 21, the acoustic environment in the vehicle interior can be faithfully reproduced by a reproduction system described later. For this reason, by using the acoustic characteristics in the passenger compartment measured in advance by the original sound field measuring system 20, it is possible to reproduce the acoustic field in the passenger compartment by the reproduction system.

  As shown in FIG. 2, the speaker unit 22 includes a front right speaker FR installed at a right door position on the front seat side of the vehicle 30, a front left speaker FL installed at a left door position on the front seat side, and a rear A rear right speaker RR installed at the right door position on the seat side and a rear left speaker RL installed at the left door position on the rear seat side are provided. Each speaker FR, FL, RR, RL is a general speaker used in a general vehicle 30.

  The audio output device 23 has a role of outputting the evaluation sound output from the computer 24 to each speaker FR, FL, RR, RL of the speaker unit 22. Note that the audio output device 23 can individually output the output destination of the evaluation sound to the speakers FR, FL, RR, and RL according to the control command of the computer 24. Note that the evaluation sound is an output sound used to calculate the acoustic characteristics of the original sound field 21 based on the recorded sound collected via the microphone 10 and the sound input device 26 of the sound recording device 1. Specifically, it corresponds to sound (for example, an M-sequence signal or a Time Stretched Pulse (TSP) signal) suitable for measuring the collected recorded sound as an impulse response.

  As described with reference to FIG. 1, the sound recording apparatus 1 includes a plurality (specifically, M) of microphones 10. The sound recording apparatus 1 is attached to the head of a dummy head D that is installed at a position at a driver's seat 31 in the passenger compartment and at a height that assumes the head position of the driver. In this way, by installing the sound recording device 1 in the driver's seat 31 and measuring the evaluation sound with the microphone 10 of the sound recording device 1, it is possible to measure the acoustic characteristics of the vehicle interior mainly composed of the driver. Become.

  The voice input device 26 has a role of outputting the output sound of the speaker unit 22 measured by the sound recording device 1 to the computer 24. Here, although the plurality of microphones 10 are installed in the sound recording device 1, the sound signal of the sound recording device 1 input in the sound input device 26 becomes an input signal input simultaneously by the plurality of microphones 10. The input is performed as a multi-channel acoustic signal.

  The computer 24 has a function of generating the above-described evaluation sound and calculating the acoustic characteristic of the original sound field 21 based on the recorded sound collected by the acoustic recording device 1 in order to measure the acoustic characteristic in the vehicle interior. is doing.

  The computer 24 is roughly configured by an evaluation sound generating unit 35, an impulse response calculating unit 36, an impulse response recording unit 37, and a control unit 38. The evaluation sound generator 35 has a function of generating an evaluation sound for collecting the impulse response described above. The evaluation sound generation unit 35 generates an evaluation sound in accordance with a control command from the control unit 38 and outputs the evaluation sound to the voice output device 23 via the control unit 38.

  The impulse response calculation unit 36 calculates an impulse response to the evaluation sound based on the recorded sound collected via the sound recording device 1 and the voice input device 26. The impulse response calculated here is calculated for each speaker in accordance with the speakers FR, FL, RR, and RL to which the evaluation sound selected by the audio output device 23 is output.

  The impulse response recording unit 37 records the impulse response calculated for each of the speakers FR, FL, RR, and RL as acoustic characteristics. The impulse response recording unit 37 may be a general hard disk or the like, or may be configured by a flash memory or the like.

  The control unit 38 has a role of performing processing necessary for obtaining acoustic characteristics for each of the speakers FR, FL, RR, and RL in the original sound field 21, and includes a CPU (Central Processing Unit) that mainly performs arithmetic control processing, It is configured by a general arithmetic processor such as a ROM (Read Only Memory) in which a program for measuring acoustic characteristics in the original sound field 21 is recorded, a RAM (Random Access Memory) used in a work area, and the like. .

  As described above, the control unit 38 causes the evaluation sound generation unit 35 to generate an evaluation sound and outputs the generated evaluation sound to the sound output device 23. In addition, the control unit 38 has a role of switching and controlling the output destination speakers FR, FL, RR, and RL of the evaluation sound output from the audio output device 23 by outputting a control command to the audio output device 23. is doing. Further, the control unit 38 causes the impulse response calculation unit 36 to calculate the impulse response for each speaker based on the recorded sound input from the voice input device 26, and the calculated impulse response for each speaker is used as the sound in the original sound field 21. As a characteristic, the impulse response recording unit 37 has a role of recording.

  FIG. 3 is a flowchart showing the acoustic characteristic measurement process of the original sound field 21 in the control unit 38.

  In the original sound field measurement system 20 configured as described above, the control unit 38 outputs a control command for generating an evaluation sound to the evaluation sound generation unit 35 (step S.1). The evaluation sound generator 35 generates an evaluation sound according to the control command of the controller 38 and outputs it to the controller 38.

  Next, the control unit 38 determines an output destination speaker (output channel) of the evaluation sound to be selected by the audio output device 23 (step S.2). Specifically, the control unit 38 determines whether to output the evaluation sound to the front right speaker FR, the front left speaker FL, the rear right speaker RR, or the rear left speaker RL. And the control part 38 outputs the output destination speaker information determined with respect to the audio | voice output apparatus 23 (step S.3), and outputs an evaluation sound with respect to the audio | voice output apparatus 23 (step S.4).

  In the audio output device 23, the output destination of the evaluation sound is set to the designated speaker according to the output destination speaker information received from the control unit 38, and the evaluation sound is output. In the sound recording device 1, output sounds output from designated speakers are collected by a plurality (M) of microphones 10, and the collected recording sounds are output to the sound input device 26. The voice input device 26 outputs the recorded sound acquired from the sound recording device 1 to the control unit 38.

  The control unit 38 acquires the recorded sound from the voice input device 26 (step S.5), and outputs an impulse response calculation processing command to the impulse response calculation unit 36 based on the acquired recorded sound to calculate the impulse response. Processing is performed (step S.6). Then, the impulse response calculated by the impulse response calculation unit 36 is recorded in the impulse response recording unit 37 in association with the speaker from which the evaluation sound is output (step S.7).

  Thereafter, the control unit 38 determines whether or not the evaluation sound output processing has been performed for all the speakers (step S.8), and there is a speaker that has not yet been subjected to the evaluation sound output processing (step S.8). In the case of No in step 8), the process proceeds to step S. The process proceeds to 2 to determine an output destination speaker that has not yet undergone evaluation sound output processing (step S.2), and the above-described processing is repeatedly executed.

  When evaluation sound output processing is performed for all speakers (Yes in step S.8), in the present embodiment, front right speaker FR, front left speaker FL, rear right speaker RR, rear left speaker RL. When the evaluation sound is output for each of the above, the control unit 38 ends the acoustic characteristic measurement process of the original sound field 21 in the original sound field measurement system 20.

In this way, the control unit 38 measures the acoustic characteristics in the original sound field 21, whereby the acoustic characteristics D _i (i is the number of microphones) between each speaker FR, FL, RR, RL and each microphone 10 are determined as the speaker FR. , FL, RR, and RL. Acoustic characteristics _{D i} obtained in this way, the impulse response recording unit 37, before the right speaker FR acoustic properties _D i (FR), before the left speaker FL acoustic properties _D i (FL), rear right speaker RR Are recorded as four types of acoustic characteristics D _i (RR) and acoustic characteristics D _i (RL) of the rear left speaker RL.

[Measurement of acoustic characteristics in playback systems]
Next, a reproduction sound field measurement system for measuring acoustic characteristics in the reproduction system will be described. In this embodiment, a laboratory is used as an example of a regeneration system. As described above, by using the laboratory as a reproduction system, the acoustic environment in the vehicle interior (original sound field 21) described above can be faithfully reproduced in the laboratory. For this reason, it is possible to reproduce the acoustic environment of any vehicle in one laboratory (reproduction system) by measuring the acoustic characteristics of different vehicles 30 using the above-described original sound field measurement system 20.

  As shown in FIG. 4, a reproduction sound field measurement system 40 includes a speaker unit 42 installed in a laboratory (reproduction system 41), an audio output device 23 that outputs audio to the speaker unit 42, and an audio output device. 23, a computer 24 that outputs an evaluation sound to the sound recording device 23, a sound recording device 1 installed in the reproduction system 41, a sound input device 26 that inputs the sound collected by the sound recording device 1, and a sound recording device Cameras (photographing devices) 44a to 44c for photographing the installation position of 1 from the front and the left and right sides, an image processing unit 43 for processing images captured by the cameras 44a to 44c, and an image by the image processing unit 43 A monitor (display device) 45 for displaying the processed image is schematically configured. Note that the acoustic recording device 1, the cameras 44a to 44c, the monitor 45, and the speaker unit 42 correspond to the acoustic measurement system according to the present invention.

  Here, the sound output device 23, the sound recording device 1, the computer 24, and the sound input device 26 used in the reproduction sound field measurement system 40 are the same as the sound output device 23 used in the original sound field measurement system 20 described above. Since the sound recording device 1, the computer 24, and the voice input device 26 have the same configuration and the same function, detailed description thereof is omitted. The sound recording device 1 is attached to the head of a dummy head D installed so as to be positioned at a height that assumes the position of the head of the listener M at the time of listening to the reproduced sound field.

  In addition, the evaluation sound generator 35, the impulse response calculator 36, the impulse response recording unit 37, and the control unit 38 that roughly configure the computer 24 also include the evaluation sound that roughly configures the computer 24 of the original sound field measurement system 20 described above. Since the generation unit 35, the impulse response calculation unit 36, the impulse response recording unit 37, and the control unit 38 have the same configuration and the same functions, detailed descriptions thereof are omitted.

  As shown in FIG. 4, the speaker unit 42 includes a plurality (N in the present embodiment) of speakers 46 arranged in a circle so as to maintain an equal distance from the sound recording device 1. The speaker 46 can output the evaluation sound output from the audio output device 23.

  Further, the speaker 46 is installed so as to be dense with respect to the output direction of the sound source in the original sound field 21 or the direction in which the sound pressure level of the sound source is high with reference to the arrangement position of the speaker unit 22 in the original sound field 21. For example, in the original sound field measurement system 20 according to the present embodiment, four speakers (speakers FR, FL, RR, RL) are provided in the original sound field 21, and the installation position (driver's seat position) of the sound recording device 1 is provided. Is used as a reference, and the speakers (speakers FR, FL, RR, RL) are respectively arranged in the right front direction, left front direction, right rear direction, and left rear direction. For this reason, as shown in FIGS. 4 and 5, the speakers 46 arranged in the reproduction sound field measurement system 40 are arranged so as to be densely arranged in the arrangement direction of the speakers in the original sound field 21 (arrangement direction). Adjustments are made.

  As shown in FIG. 5, the sound source direction of the original sound field and the sound source direction in the playback system can be made common by arranging the speakers 46 densely in each door speaker direction of the vehicle 30 to be the original sound field 21. It becomes possible to improve the reproducibility of the original sound field in the reproduction system, and the reproduction accuracy such as a sense of localization can be improved. Although it is not realistic to change the arrangement of the speakers 46 every time the reproduction target is changed, if the sound source direction of the sound field to be reproduced is almost fixed, the sound source direction (for example, the vehicle interior) In the reproduction of the sound field, it is conceivable that the speakers 46 are densely arranged in the direction of door speakers, tweeters, center speakers, and the like.

  4 and 5 show the case where the speaker 46 is arranged two-dimensionally (planarly), but the arrangement position of the speaker 46 is two-dimensionally arranged. Without limitation, the speaker 46 may be arranged three-dimensionally. Even when the speakers 46 are arranged three-dimensionally, it is possible to improve the reproduction accuracy by densely arranging the speakers 46 in the direction of the sound source of the original sound field 21 or in the direction where the sound pressure level is high.

  For example, the speakers installed at the left and right front and rear positions of the vehicle 30 are generally installed at the lower part of the door portion (near the feet). On the other hand, a speaker such as a tweeter is often installed on the A-pillar of the vehicle (the left and right pillars of the front window), and the audio signal output position is higher than the speaker installed on the lower part of the door (near the feet). Will be located in place. For this reason, it is possible to improve the reproduction accuracy by installing the speaker 46 at a high position assuming the tweeter installation position or installing the speaker 46 at a low position assuming the door installation speaker.

  Similar to the audio output device 23 of the original sound field measurement system 20 described above, the audio output device 23 can individually output the output destination of the evaluation sound to each speaker 46 according to the control command of the computer 24. .

  Here, since the sound recording apparatus 1 according to the present embodiment has a configuration in which a plurality of microphones 10 are arranged on the outer surface 9 of the hemispherical base portion 3, the head side surface (face side surface) 6 and the outside of the base portion 3 are arranged. If it is the range of the closed space 8 formed by the surface 9, even if the listener M's ear position is shifted, it is possible to ensure an acoustic environment with good reproduction accuracy. However, in the sound recording device 1 according to the present embodiment, since the control area is limited to the vicinity of the ear, if the listening position of the listener M deviates greatly and the ear position exceeds the range of the closed space 8, There is a possibility that the reproduction accuracy of acoustic characteristics is greatly deteriorated. On the other hand, when the sound recording apparatus 1 records sound corresponding to the impulse response, the reproduction system 41 uses the position of the microphone 10 when the reproduction system 41 measures the acoustic characteristics and the obtained sound field reproduction filter. The adjustment of the listener M when reproducing the acoustic environment of the original sound field 21 by reproducing the acoustic environment of the original sound field 21 by the reproduction system 41 is performed by adjusting the ear position of the listener M when reproducing the acoustic environment of the original sound field 21. The fluctuation range of the ear position can be made to correspond to the closed space 8 with high accuracy.

  Therefore, in the reproduction sound field measurement system 40 according to the present embodiment, as shown in FIG. 4, the front direction, the left direction, and the listening direction of the listener M (the installation position of the sound recording device 1) on the same horizontal plane, Cameras 44a to 44c for head / ear position photographing are set at three positions in the right direction. Specifically, the cameras 44a to 44c are equidistant annular positions where the speakers 46 are arranged, and are installed at the height position of the listener's head. The camera 44a is provided at the front position of the listener, the camera 44b is provided at the left side position of the listener, and the camera 44c is provided at the right side position of the listener.

  The front image of the listener photographed by the camera 44a, the left side image of the listener photographed by the camera 44b, and the right side image of the listener photographed by the camera 44c are output to the image processing unit 43. .

  The image processing unit 43 acquires images captured by the cameras 44a to 44c, corrects each acquired image in consideration of ease of viewing (as displayed on the mirror), and acquires the acquired images. The images are combined into one image so that the listener can easily compare them. Furthermore, in the image processing unit 43, a guide for showing the ear position and the center position of the face as shown in FIG. 6 is provided so that the listener can easily adjust the position of the ear via the monitor 45. The lines 47 and 48 and the ear position marker 49 are added to the front image and the left and right side images.

  The monitor 45 is installed at the front position of the listener M, and a front image and left and right side images of the listener M that has been subjected to image processing by the image processing unit 43 are displayed on the monitor 45. The listener M confirms the front image and the left and right side images displayed on the monitor 45, and matches the center position of the face and the ear position based on the guide lines 47 and 48 and the marker 49 of the image, thereby optimizing the position. It becomes possible to listen to the impulse input.

  FIG. 7 is a flowchart showing an acoustic characteristic measurement process of the reproduction system 41 in the control unit 38.

  In the reproduction sound field measurement system 40 configured as described above, the control unit 38 outputs a control command for generating the evaluation sound to the evaluation sound generation unit 35 (step S.11). The evaluation sound generator 35 generates an evaluation sound according to the control command of the controller 38 and outputs it to the controller 38.

  Next, the control part 38 determines the output destination speaker (output channel) of the evaluation sound selected in the audio | voice output apparatus 23 (step S.12). Specifically, the control unit 38 determines to which of the N speakers 46 the evaluation sound is to be output. And the control part 38 outputs the output destination speaker information determined with respect to the audio | voice output apparatus 23 (step S.13), and outputs an evaluation sound with respect to the audio | voice output apparatus 23 (step S.14).

  The audio output device 23 sets the output destination of the evaluation sound to the designated speaker 46 according to the output destination speaker information received from the control unit 38, and outputs the evaluation sound. In the sound recording apparatus 1, the output sound output from the designated speaker 46 is collected by a plurality (M) of microphones 10, and the collected recording sound is output to the sound input device 26. The voice input device 26 outputs the recorded sound acquired from the microphone 10 of the sound recording device 1 to the control unit 38.

  The control unit 38 acquires a recorded sound from the voice input device 26 (step S.15), and outputs an impulse response calculation processing command to the impulse response calculation unit 36 based on the acquired recorded sound to calculate the impulse response. Processing is performed (step S.16). Then, the impulse response calculated by the impulse response calculation unit 36 is recorded in the impulse response recording unit 37 in association with the speaker 46 from which the evaluation sound is output (step S.17).

  Thereafter, the control unit 38 determines whether or not the evaluation sound output processing has been performed for all the speakers 46 (step S.18), and there is a speaker 46 that has not yet performed the evaluation sound output processing (step S.18). In the case of No in S.18), the process proceeds to step S.18. 12, the output destination speaker 46 that has not yet been subjected to the process of outputting the evaluation sound is determined (step S.12), and the above-described processing is repeatedly executed.

  When the evaluation sound output process is performed for all the speakers 46 (Yes in step S.18), that is, the evaluation sound is output to each of the N speakers 46, whereby each speaker 46 has an impulse. When the response calculation process is performed, the control unit 38 ends the acoustic characteristic measurement process of the reproduction system 41 in the reproduction sound field measurement system 40.

The acoustic characteristics measured in the reproduction sound field measuring system 40 are obtained based on a number of impulse responses between the N speakers 46 of the speaker unit 42 and the M microphones 10 of the sound recording device 1. The acoustic characteristics A _ij obtained based on all the impulse responses are recorded in the impulse response recording unit 37 (i is the number of microphones 10 and j is the number of speakers 46 of the reproduction system 41).

[Calculation of sound field reproduction filter]
Then, based on the acoustic characteristics _{D i} of each speaker FL, FR, RR, RL calculated in the original sound field measuring system 20, and the acoustic characteristics A _ij calculated in the reproduction sound field measuring system 40, the reproduction system 41 The process for calculating the sound field reproduction filter for realizing the acoustic environment of the original sound field 21 will be described.

  FIG. 8A is a block diagram showing a filter calculation device 50 for calculating a sound field reproduction filter.

  The filter calculation device 50 is roughly configured by a filter calculation processing unit 51, an original sound field characteristic recording unit 52, a reproduction sound field characteristic recording unit 53, and a filter information recording unit 54.

The original sound field characteristic recording unit 52, the speakers FL measured in the original sound field 21, FR, RR, acoustic characteristics D _i of RL is recorded, similarly to the impulse response recording unit 37, and a hard disk, a flash memory It is comprised by the general recording devices, such as. Similarly, the sound characteristic A _ij measured by the reproduction system 41 is recorded in the reproduction sound field characteristic recording unit 53, and is constituted by a general recording device such as a hard disk.

  The filter information recording unit 54 is a recording medium on which the sound field reproduction filter calculated by the filter calculation processing unit 51 is recorded. Similarly to the original sound field characteristic recording unit 52 and the reproduction sound field characteristic recording unit 53, the filter information recording unit 54 is also configured by a general recording device.

Based on the acoustic characteristic D _i recorded in the original sound field characteristic recording unit 52 and the acoustic characteristic A _ij recorded in the reproduction sound field characteristic recording unit 53, the filter calculation processing unit 51 performs the speaker FL, FR, RR, A process for calculating the sound field reproduction filter Q _j for each RL is performed. The filter calculation processing unit 51 is used for a CPU (Central Processing Unit) that mainly performs calculation control processing, a ROM (Read Only Memory) in which a program for calculating a sound field reproduction filter is recorded, a work area, and the like. It is constituted by a general arithmetic processor such as a random access memory (RAM).

The filter calculation processing unit 51 calculates the sound field reproduction filter Q _j by solving the following simultaneous equations (Formula 1).

Here, the element A _ij of the matrix A indicates the acoustic characteristics between the speaker j and the microphone i in the reproduction system, the matrix Q _j indicates the sound field reproduction filter to be obtained, and the matrix D _i indicates the original sound It shows the acoustic characteristics of the field.

In addition, i indicates the number of microphones 10 installed in the sound recording apparatus 1, and M microphones 10 are installed in the sound recording apparatus 1 in the present embodiment.
i = 1, 2,..., M.

Furthermore, j indicates the number of speakers in the reproduction system, and N speakers 46 are installed in the speaker unit 42 of the reproduction system 41 in the present embodiment.
j = 1, 2,..., N.

The filter calculation processing unit 51 performs sound field reproduction filters Q _j (Q ₁ to Q ₁ corresponding to the speakers FR, FL, RR, and RL of the speaker unit 22 based on the above-described Expression 1 according to the flowchart shown in FIG. Q _N ) is obtained (step S.21).
At this time, the filter calculation processing unit 51 is based on the acoustic characteristic A _ij of the reproduction system 41.
(1) a sound field reproduction filter Q _j (FR) for the acoustic characteristic D _i (FR) of the original sound field 21;
(2) a sound field reproduction filter Q _j (FL) for the acoustic characteristics D _i (FL) of the original sound field 21;
(3) a sound field reproduction filter Q _j (RR) with respect to the acoustic characteristic D _i (RR) of the original sound field 21;
(4) A sound field reproduction filter Q _j (RL) for the acoustic characteristic D _i (RL) of the original sound field 21 is calculated.

Then, the filter calculation processing unit 51 causes the filter information recording unit 54 to record the calculated sound field reproduction filters Q _j (FR), Q _j (FL), Q _j (RR), Q _j (RL) (step S.22), the calculation process of the sound field reproduction filter is terminated. In the flowchart shown in FIG. 8B, only the calculation process of one sound field reproduction filter Q _j for one acoustic characteristic D _i is shown for convenience. However, as described above, each acoustic characteristic of the original sound field 21 is shown. (Each sound field reproduction filter (acoustic characteristics D _i (FR), acoustic characteristics D _i (FL), acoustic characteristics D _i (RR), acoustic characteristics D _i (RL)) of (1) to (4) described above) (1) to (4) of the sound field reproduction filter Q _j (FR), sound field reproduction filter Q _j (FL), sound field reproduction filter Q _j (RR), sound field reproduction filter Q _j (RL)). Are calculated and recorded in the filter information recording unit 54.

[Sound environment reproduction processing of the original sound field in the playback system]
Next, a process of reproducing the acoustic environment (sound field) in the vehicle interior that is the original sound field 21 in the laboratory that is the reproduction system 41 will be described. The reproduction of the acoustic environment of the original sound field 21 in the reproduction system 41 is realized by the sound field reproduction system.

  FIG. 9 is a block diagram showing a schematic configuration of the sound field reproduction system 60. As shown in FIG. 9, the sound field reproduction system 60 includes a speaker unit 42 installed in a laboratory serving as a reproduction system 41, an audio output device 61 that outputs audio to the speaker unit 42, and an audio output device 61. A computer 62 for outputting an evaluation sound, an audio device 63 capable of outputting a multi-channel sound signal, a sound input device 26 for outputting a sound signal reproduced by the audio device 63 to the computer 62, Cameras 44a to 44c for photographing the head position of a listener M who listens to music in the sound field reproduction system 60 from the front and left and right sides, and an image processing unit for processing images taken by the cameras 44a to 44c 43 and a monitor 45 for displaying the image processed by the image processing unit 43.

  Here, the audio input device 26 used in the sound field reproduction system 60, the speaker unit 42, the cameras 44 a to 44 c, the image processing unit 43, and the monitor 45 are used as audio inputs used in the reproduction sound field measurement system 40. Since the apparatus 26, the speaker unit 42, the cameras 44a to 44c, the image processing unit 43, and the monitor 45 have the same configuration and the same functions, detailed descriptions thereof are omitted.

  The audio output device 61 has a role of outputting the audio signal output from the computer 62 to each speaker 46 of the speaker unit 42. Note that the audio output device 61 can output the evaluation sound to all the speakers 46 at the same time.

  The audio device 63 is a device that reads out music information recorded on a recording medium such as a CD (Compact Disc), a DVD, or an MD (MiniDisc) and outputs the music information as an acoustic signal. The audio device 63 can output a multi-channel sound signal. For example, a multi-channel sound such as a 5.1-channel sound signal recorded on a DVD can be reproduced. . Note that, in the audio device 63 according to the present embodiment, a case where a two-channel (stereo sound source) sound signal recorded on a recording medium is output will be described.

  The audio device 63 (for example, an in-vehicle audio device) reads two-channel (stereo sound source) sound signals recorded on the recording medium, and uses the stereo sound source for each speaker FR, FL, RR of the speaker unit 22 installed in the original sound field 21. , And distribute to the acoustic signal of 4 channels corresponding to RL. Specifically, the right component of the stereo sound source is distributed to the speakers FR and RR, and the left component is distributed to the speakers FL and RL. As shown in FIG. 10, an acoustic signal S (FR) emitted from the speaker FR and the speaker An acoustic signal S (FL) emitted from the FL, an acoustic signal S (RR) emitted from the speaker RR, and an acoustic signal S (RL) emitted from the speaker RL are output. At this time, depending on the setting on the audio device 63 side, the audio device 63 outputs an acoustic signal obtained by performing acoustic signal processing such as an equalizer for each of the four channels.

  The computer 62 acquires the four-channel acoustic signal reproduced by the audio device 63 via the audio input device 26, and performs acoustic processing on the acquired acoustic signal, thereby obtaining the acoustic signal output in the reproduction system 41. In addition, it has a role of processing so as to have the same acoustic characteristics as the acoustic signal output in the original sound field 21.

  The computer 62 is roughly configured by a control unit 65, a convolution operation processing unit 66, and a sound field reproduction filter recording unit 67. The sound field reproduction filter recording unit 67 records the sound field reproduction filter calculated by the filter calculation device 50 described above. The sound field reproduction filter recording unit 67 is configured by a general recording device.

The convolution operation processing unit 66 performs a convolution operation on the acoustic signal input by the sound input device 26 using a sound field reproduction filter recorded in the sound field reproduction filter recording unit 67 in accordance with a control command of the control unit 65. Processing is performed, and acoustic processing is performed on the acoustic signals output from the N speakers 46 of the speaker unit 42. Specifically, as shown in FIG. 10, four-channel acoustic signals (acoustic signal S (FR), acoustic signal S (FL), acoustic signal S ( RR) and acoustic signal S (RL)) are converted into sound field reproduction filters (sound field reproduction filter Q _j (FR) and sound field reproduction filter Q _j (FL) corresponding to each channel by the convolution operation processing unit 66. ), Convolution calculation processing 70 to 73 using any one of the sound field reproduction filter Q _j (RR) and the sound field reproduction filter Q _j (RL) is performed.

  The acoustic signals of each channel subjected to the convolution operation are added by the adders K1 to KN for each sound output of the same channel subjected to the convolution operation by the respective sound field reproduction filters, and correspond to the number of speakers 46 of the reproduction system 41. Acoustic processing is performed on the acoustic signals of N channel components. Then, the convolution operation processing unit 66 outputs an acoustic signal having N channel components from the control unit 65 to the audio output device 61, and the audio output device 61 supports each channel (1 to N channels). Are simultaneously output from N speakers 46.

  In this way, when the listener M listens to the acoustic signal output from each speaker 46 at the listening position of the sound field reproduction system 60, the reproduction system 41 can reproduce the acoustic environment of the original sound field 21. It becomes. In addition, when the listener M listens to the acoustic signal, the control range in which the acoustic environment of the original sound field 21 can be reproduced is an area corresponding to the closed space 8 near the ear 2 position. Even if it moves slightly, it becomes possible to ensure a sufficiently reproducible acoustic environment.

  Furthermore, the sound field reproduction system 60 is provided with cameras 44 a to 44 c, an image processing unit 43, and a monitor 45, as in the reproduction sound field measurement system 40. For this reason, as shown in FIG. 11, a listener M who listens to music can check the left and right ear positions and the center position of the face based on the image displayed on the monitor 45. By confirming the image displayed on the monitor 45 in this way, the head position capable of obtaining the optimum acoustic environment can be confirmed, and therefore the target range of the control points secured by the closed space 8 In combination, it is possible to more reliably realize an optimal acoustic environment.

  The acoustic measurement system and the sound recording apparatus according to the present invention have been described in detail with reference to the drawings. However, the acoustic measurement system and the sound recording apparatus according to the present invention are not limited to the above-described embodiments. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above-described embodiment, after the sound field reproduction filter is calculated by the filter calculation device 50, the calculated sound field reproduction filter is recorded in the sound field reproduction filter recording unit 67, and the convolution calculation processing unit 66 performs the convolution calculation. However, the sound field reproduction system 60 may calculate the sound field reproduction filter.

  In the above-described embodiment, the image processing unit 43 is provided separately from the computers 24 and 62, and images of the images taken by the cameras 44a to 44c regardless of the control of the control units 38 and 65 of the computers 24 and 62. The image processing unit 43 is integrally configured as one of the functional units of the computers 24 and 62, and the image processing unit 43 is controlled by the control units 38 and 65. It may be configured to perform image processing or the like.

It is a figure which shows schematic structure of the sound recording device which concerns on embodiment, Comprising: (a) is a side view, (b) is a front view, (c) has shown sectional drawing. It is the figure which showed schematic structure of the original sound field measuring system which concerns on embodiment. It is the flowchart which showed the acoustic characteristic measurement process of the original sound field in the control part of the original sound field measurement system which concerns on embodiment. It is the figure which showed schematic structure of the reproduction sound field measurement system which concerns on embodiment. It is the figure which showed the response | compatibility with the arrangement position of the speaker in the reproduction sound field measurement system which concerns on embodiment, and the arrangement position of the speaker in an original sound field measurement system. It is the figure which showed the example of an image shown on the monitor of the reproduction | regeneration sound field measurement system which concerns on embodiment. It is the flowchart which showed the acoustic characteristic measurement process of the reproduction | regeneration system in the control part of the reproduction | regeneration sound field measurement system which concerns on embodiment. (A) is the block diagram which showed schematic structure of the filter calculation apparatus which concerns on this Embodiment, (b) is calculation of the sound field reproduction filter in the filter calculation process part of the filter calculation apparatus which concerns on embodiment. It is the flowchart which showed the process. It is the block diagram which showed schematic structure of the sound field reproduction system which concerns on embodiment. It is explanatory drawing for demonstrating the convolution calculation process by the convolution calculation process part which concerns on embodiment. It is the figure which showed the example of an image shown on the monitor of the sound field reproduction system which concerns on embodiment.

Explanation of symbols

1 ... Sound recording device (acoustic recording device, sound measurement system)
2 ... Ear 3 ... Base (of sound recording device)
4 ... Arch part 5 (of the sound recording device) ... Recess 6 of (base part) ... Side surface 8 ... Closed space 9 ... Outer surface 10 of (base part) ... Microphone 20 (of sound recording device) ... Original sound field measurement system 21 ... Original sound field 22, 42 ... Speaker unit 23, 61 ... Audio output device 24, 62 ... Computer 26 ... Audio input device 30 ... Vehicle 31 ... Driver's seat 35 ... Evaluation sound generation unit 36 ... Impulse response calculation unit 37 ... Impulse response Recording unit 38, 65 ... (computer) control unit 40 ... reproduction sound field measurement system 41 ... reproduction system 43 ... image processing units 44a to 44c ... camera (imaging device, acoustic measurement system)
45 ... Monitor (display device, acoustic measurement system)
46 ... Speaker (speaker, acoustic measurement system)
47, 48 ... guide line 49 ... marker 50 ... filter calculation device 51 ... filter calculation processing unit 52 (of filter calculation device) ... original sound field characteristic recording unit 53 (of filter calculation device) ... reproduced sound field (of filter calculation device) Characteristic recording unit 54 ... Filter information recording unit 60 (of the filter calculation device) ... Sound field reproduction system 63 ... Audio equipment 66 ... Convolution calculation processing unit 67 ... Sound field reproduction filter recording units 70 to 73 ... Convolution calculation processing D ... Dummy head M ... listeners K1 to KN ... adder A _ij ... acoustic characteristics D _i (of the reproduction system) ... acoustic characteristics Q _j (of the original sound field) ... sound field reproduction filter FL ... front left speaker FR ... front right speaker RL ... rear Left speaker RR ... Rear right speaker S (FR), S (FL), S (RR), S (RL) ... Acoustic signal

Claims (4)

An acoustic measurement system that measures acoustic characteristics from each speaker to each microphone in the acoustic space by recording acoustic signals output from a plurality of speakers installed in a specific acoustic space with a plurality of microphones,
A dummy head installed at a measurement target position in the acoustic space or a tuft base that can secure a certain closed space raised from the dummy head or the head side surface of the listener with reference to the ear position of the listener; ,
A plurality of microphones disposed on the outer surface of the bald base;
An imaging device for imaging the dummy head or the listener's head installed at the measurement target position in the acoustic space;
An acoustic measurement system comprising: a display device that displays the state of the head imaged by the imaging device so as to be visible at the measurement target position. By measuring the acoustic characteristics of the acoustic space in the reproduction system using the acoustic measurement system, based on the acoustic characteristics of the reproduction system and the acoustic characteristics measured in the acoustic space of the original sound field, When the sound field reproduction filter for reproducing the acoustic environment of the original sound field is calculated,
A plurality of speakers for outputting acoustic signals in the reproduction system;
The plurality of speakers are adapted to correspond to an input direction of an acoustic signal with reference to a microphone position at which the acoustic characteristics are measured in the original sound field and a direction of a high sound pressure level of the input acoustic signal. The acoustic measurement system according to claim 1, wherein the acoustic measurement system is arranged in a direction based on the measurement target position of the system. The plurality of microphones arranged on the outer surface of the bald base has an interval between adjacent microphones that is equal to or less than ½ wavelength of an upper limit frequency to be measured for an acoustic signal recorded by the microphone. The acoustic measurement system according to claim 1, wherein the acoustic measurement system is set so as to have an interval. An acoustic recording device that measures acoustic characteristics from each speaker to each microphone in the acoustic space by measuring an acoustic signal output from a speaker installed in a specific acoustic space with a plurality of microphones. A fixed head that can secure a certain closed space raised from the side of the head of the dummy head or the listener on the basis of the position of the dummy head or the ear of the listener installed at the measurement target position;
A sound recording apparatus comprising: the plurality of microphones disposed on an outer surface of the bunch base.

Images