WO2022059364A1

WO2022059364A1 - Sound processing system, sound processing method, and recording medium

Info

Publication number: WO2022059364A1
Application number: PCT/JP2021/028343
Authority: WO
Inventors: 僚太山口; 孝司大杉
Original assignee: 日本電気株式会社
Priority date: 2020-09-17
Filing date: 2021-07-30
Publication date: 2022-03-24
Also published as: JPWO2022059364A1

Abstract

This sound processing system comprises: a sound source that emits a sound, which is based on a prescribed sound source signal; a sound reception unit that acquires a sound reception signal of an arrived sound; a calculation unit that acquires, from the sound reception signal, the impulse response from the sound source to the sound reception unit; and a sound absorption material that covers an object, said object being on the path of a reflected sound that arrives at the sound reception unit at least within a prescribed observation period from the production of the aforementioned sound.

Description

Sound processing system, sound processing method, and recording medium

The present invention relates to an acoustic processing system, an acoustic processing method, and a recording medium. The present invention relates to, for example, a method of acquiring a head-related impulse response (HRIR) for reproducing a sound having a stereoscopic effect using headphones, earphones, or the like.

Conventionally, a method of reproducing a sound having a three-dimensional effect has been proposed. For example, Patent Document 1 discloses a method of synthesizing a two-channel acoustic signal by convolving each of the sound wave transmission characteristics from a sound source to the left and right ears of a listener as a head-related transfer function into a source sound. By presenting the sound based on the acoustic signal obtained by this method to the left and right ears of the listener, sound image localization in the direction of the sound source is realized. HRIR corresponds to the head related transfer function expressed as an impulse response in the time domain.
On the other hand, it is known that even if an acoustic signal synthesized in advance using a common HRIR is used, a desired stereoscopic effect cannot be obtained for 30% or more of the listeners. Therefore, it is important to obtain HRIRs for individual listeners.

Patent Document 1 describes a measuring device that measures a head transmission function by installing a microphone in the subject's ear with a signal of a pseudo sound source emitted from around the subject's head. This measuring device has a sound source storage unit, an output control unit, an output unit, an input unit, a key input unit that supports the start of measurement, an input control unit that records measurement data in the data storage unit, and a reflector. Then, this measuring device starts the input in synchronization with the output of the output control unit at the time of measurement in the measurement room not subjected to the non-reverberation processing, and ends the data input before the reverberation sound reaches the input unit. However, it is characterized in that a reflector is arranged in the path of the reflected sound reaching the input unit within the measurement time.

Japanese Patent Application Laid-Open No. 8-307988

However, a special environment is required to obtain HRIR. The special environment refers to an environment where there is no reflection such as an anechoic chamber, or an environment where the influence is negligible and there is little reflection. This is because if the HRIR includes the influence of reflection, it becomes impossible to reproduce the sound waves arriving at the left and right ears from the target direction of the sound image localization. In this respect, the measuring device described in Patent Document 1 reduces the influence of reflection by arranging a reflector in the path of the reflected sound to block the reflection to the microphone. Therefore, it is difficult to arrange a reflector in the path of the reflected sound except for an acoustic engineer who has knowledge about the path of the reflected sound.

The present invention has been made to solve the above-mentioned problems. An example of an object of the present invention is to provide an acoustic processing system, an acoustic processing method, and a recording medium capable of acquiring HRIR more easily.

According to the first aspect of the present invention, the sound processing system includes a sound source that emits a sound based on a predetermined sound source signal, a sound receiving unit that acquires a sound receiving signal of the incoming sound, and the sound source from the sound receiving signal. A calculation unit that acquires an impulse response from the sound receiving unit to the sound receiving unit, and a sound absorbing material that covers an object on the path of the reflected sound that arrives at the sound receiving unit within at least a predetermined observation period from the generation of the sound. Be prepared.

Further, according to the second aspect of the present invention, the sound processing method includes a sound absorbing material that covers an object on the path of the reflected sound that arrives at the sound receiving portion within at least a predetermined observation period from the generation of the sound from the sound source. A first step in which the sound source emits a sound based on a predetermined sound source signal, and the sound receiving unit acquires a sound receiving signal of the incoming sound. It has a second step and a third step in which the arithmetic processing unit acquires an impulse response from the sound source to the sound receiving unit from the sound receiving signal.

Further, according to the third aspect of the present invention, the recording medium is a sound absorbing material that covers an object on the path of the reflected sound that arrives at the sound receiving portion within at least a predetermined observation period from the generation of the sound from the sound source. A computer of a sound processing system provided with a first step in which the sound source emits a sound based on a predetermined sound source signal, a second step in which the sound receiving unit acquires a sound receiving signal of the incoming sound, and an operation. The processing unit stores a program for executing the third step of acquiring an impulse response from the sound source to the sound receiving unit from the sound receiving signal.

According to one aspect of the present invention, HRIR can be obtained more easily.

It is a top view which shows the structural example of the acoustic processing system which concerns on 1st Embodiment. It is a side view which shows the structural example of the acoustic processing system which concerns on 1st Embodiment. It is a schematic block diagram which shows the hardware configuration example of the acoustic processing apparatus which concerns on 1st Embodiment. It is a schematic block diagram which shows the functional structure example of the acoustic processing apparatus which concerns on 1st Embodiment. It is a flowchart which shows the example of the HRIR measurement processing which concerns on 1st Embodiment. It is a side view which shows the structural example of the acoustic processing system which concerns on 2nd Embodiment. It is a schematic block diagram which shows the functional structure example of the control part which concerns on 2nd Embodiment. It is a flowchart which shows the example of the measurement environment determination processing which concerns on 2nd Embodiment. It is explanatory drawing which shows an example of the structure of the said embodiment.

Hereinafter, the acoustic processing system according to a plurality of embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
The sound processing system according to the first embodiment includes a sound source for emitting sound, a sound receiving unit for acquiring a sound receiving signal of the incoming sound, a sound absorbing material for absorbing the incoming sound, and an acoustic processing device. .. An example of the functional configuration of the sound processing device 10 will be described later.
FIG. 1 is a plan view showing a configuration example of the acoustic processing system 1 according to the present embodiment. FIG. 2 is a side view showing a configuration example of the sound processing system 1 according to the present embodiment. FIG. 2 shows sides that pass through the AA'line of FIG. 1 and are vertically parallel.

In the example shown in FIGS. 1 and 2, the sound processing system 1 is used in the indoor space Rm. The space Rm may be a room without special soundproofing and reverberation equipment as a whole space. That is, the space Rm is not limited to a soundproof room, a laboratory, or the like, but may be an office room, a classroom, a meeting room, a living room, or the like. The space Rm has a substantially rectangular parallelepiped shape and has a rectangular shape in a plan view. The space Rm is surrounded by four sides, one bottom surface, and one top surface. The top surface is a surface facing the bottom surface, and is represented above the bottom surface in FIGS. 1 and 2. The side surface, bottom surface and top surface are collectively referred to as the inner surface. The side surface, bottom surface, and top surface form a wall surface, floor surface, and ceiling, respectively. In the space Rm, two speakers Sp, a sound absorbing material As, and a seat Pf are arranged as sound sources for radiating sound.

The two speaker Sps are within a predetermined range from one side (hereinafter referred to as a speaker installation side) which is an intersection line where two adjacent side surfaces (hereinafter referred to as adjacent surfaces) intersect among the four sides of the space Rm. They are installed in close proximity to each other. However, the two speakers Sp are installed at different height positions in the vertical direction as shown in FIG. The two speakers Sp may be distinguished from each other by calling them speakers Sp01, Sp02, or the like. Of the two speakers Sp, the speaker Sp01 appears in FIG. 1, and the speaker Sp02 installed at a position lower than the speaker Sp01 does not appear. A reproduction signal is input from the sound processing device 10 to any one speaker Sp (speaker Sp01 in the example shown in FIG. 1). The speaker Sp radiates (reproduces) a sound based on a sound source signal input from the sound processing device 10.

The seat Pf is installed so that its central portion faces a position on the bisector of the angle formed by the adjacent surfaces and at a predetermined distance (for example, 1 to 2 m) from each speaker Sp. ing. The seat Pf has a seat plate and a backrest, which allow the subject Sb to be stationary and supported in a sitting position. The subject Sb is a person to be measured for HRIR from the speaker Sp to the left and right ears.

The sound absorbing material As is installed so as to cover at least a part of the inner surface of the space Rm. In the examples shown in FIGS. 1 and 2, the sound absorbing material As is installed so as to cover a part of the bottom surface and a part of the adjacent surface. Although not shown, a sound absorbing material may be installed to cover the seat Pf. The sound absorbing material As includes a material having a sufficiently low reflectance of the incoming sound. The sound absorbing material As may be a material that absorbs the energy of the sound and dissipates it as heat by converting most of the energy of the vibration of the incoming sound into heat. As the sound absorbing material As, for example, glass wool, rock wool, urethane sponge, or the like can be used. The sound absorbing material may also be referred to as a sound insulating material, a soundproofing material, or the like. The area where the sound absorbing material As is installed will be described later.

A microphone Mic is attached to each of the left and right ears of the subject Sb as a sound receiving part. Microphones attached to the left and right ears are distinguished by calling them microphones MicL and MicR, respectively. The microphones MicL and MicR each receive the sound arriving at their own unit and convert the received sound into a sound receiving signal. The microphones MicL and MicR each output the converted sound receiving signal to the sound processing device 10. In the following description, the sound receiving signals output from the microphones MicL and MicR may be referred to as a left sound receiving signal and a right sound receiving signal, respectively.

The sound wave radiated from the speaker Sp propagates on various paths to the microphones MicL and MicR. As illustrated in FIG. 1, when no object is installed between the speaker Sp and the microphone MicL and MicR, a part of the sound wave radiated from the speaker Sp is directly transmitted to the microphone MicL and MicR. It's coming. The other part of this sound wave is reflected by the surface of an object arranged on the path, and arrives at the microphones MicL and MicR as reflected sound.

Here, it is assumed that the sound wave S emitted by the speaker Sp includes a reflection point on the surface of the object as a propagation path and is reflected at the reflection point. In this case, the reflected wave _Srn observed at the sound receiving point where any of the microphones Mic is installed is represented by the equation (1).

In the formula (1), R and L indicate the reflectance of the sound wave at the reflection point and the attenuation rate according to the distance, respectively.
In general, since there are innumerable reflection points, the reflected wave Sr that arrives at the sound receiving point corresponds to a composite of the reflected waves _Srn for each reflection point as shown in the equation (2). In equation (2), Σ represents the sum between the reflection points. The set of these reflection points corresponds to the surface of various reflectors that reflect the sound coming from the speaker Sp.

Therefore, the sound wave S'arriving at the sound receiving point is a combination of the component of the direct wave S from the speaker Sp and the component of the reflected wave Sr as shown in the equation (3).

On the other hand, the head impulse response indicates the propagation characteristics of the sound wave from the sound source to each ear of the subject Sb. In other words, the head impulse response includes the reflection and diffraction characteristic of the sound wave arriving from the sound source on the surface of the head of the subject Sb (for example, the pinna). To obtain a pure head impulse response, it is expected to eliminate the effects of reflected waves. Conventionally, it has been common to measure the head impulse response in an environment such as an anechoic chamber where sound wave reflection does not occur. This is because it does not include the contribution of the reflected sound by the object installed on the propagation path of the sound wave.

In the acoustic processing system 1 according to the present embodiment, the head impulse response includes at least a period due to the reflection and diffraction of sound waves in the head (hereinafter referred to as a head transmission period), and the sound reflected by other objects. Reduce the ingredients. Therefore, in the sound processing apparatus 10, at least a period including a head transmission period is set in advance as an observation period of the head impulse response. The head-related transfer period depends on the size of the human head, but is typically about 1 to 3 ms starting from the time when the direct wave coming from the speaker Sp first arrives at the head of the subject Sb. It will be a period. Therefore, by covering the region of the reflector that brings about the reflected sound arriving at the microphones MicL and MicR at least within the observation period with the sound absorbing material As, the component of the reflected sound can be reduced. Even if the sound absorbing material As is installed, it does not hinder the use of the space Rm as much as the reflector, and the load related to the work related to the installation is light. Therefore, as illustrated in FIG. 1, HRIR can be acquired even in a common environment such as a corner of a space Rm. However, the positional relationship between the sound source and the seat Pf or the subject Sb is not limited to those exemplified in FIGS. 1 and 2. For example, the seat Pf may be installed in the central portion of the space Rm. Further, the shape of the space Rm is not limited to that exemplified in FIGS. 1 and 2. For example, the shape of the space Rm may be a cylinder.

In the examples shown in FIGS. 1 and 2, the area where the sound absorbing material As is installed is a square partial area including the seat Pf from the speaker installation side on the bottom surface and a bottom surface partial area of each of the two adjacent surfaces. It includes a region extending from the portion in contact with the speaker to a height obtained by adding a predetermined height to the height of at least two speakers Sp01 and Sp02, whichever is higher. The time from the time when the speaker emits sound to the starting point of the observation period (hereinafter, observation start time) is calculated based on the distance from the speaker Sp to the subject Sb and the speed of sound. The observation start time may be set in advance in the sound processing device 10, or may be calculated based on the position of the speaker Sp and the position of the seat Pf or the subject Sb. Further, the region where the sound absorbing material As is installed may include a portion where the reflected sound reaches the microphones MicL and MicR within the observation period, and the size and shape of the region are exemplified in FIGS. 1 and 2. It is not limited to what is done. For example, the shape of the region covering the floor surface with the sound absorbing material As may be fan-shaped as illustrated in FIG. 9, and may not necessarily include the position of the seat Pf.

The intensity of the reflected sound coming from the sound absorbing material As to each of the microphones MicL and MicR is not completely zero, but it is sufficiently lower than the intensity of the direct sound. Generally, when two sounds having different intensities are presented to a subject, a phenomenon (masking) is known in which a weak sound is drowned out by a strong sound and cannot be heard. According to the sound absorbing material As, the S / N ratio when the direct sound component is a signal component and the reflected sound component is a noise component can be reduced to the extent that the reflected sound cannot be perceived. Therefore, even with the head impulse response acquired by the acoustic processing system 1 according to the present embodiment, it is possible to aurally realize a stereoscopic effect similar to that of the head impulse response measured in the anechoic chamber.

Next, the configuration of the sound processing device 10 according to the present embodiment will be described.
FIG. 3 is a schematic block diagram showing a hardware configuration example of the sound processing device 10 according to the present embodiment.
The sound processing device 10 includes a control unit 110, a storage unit 130, an input / output unit 140, a display unit 150, and an operation unit 160. The sound processing device 10 may be configured as a dedicated device or may be realized by a general-purpose computer.

The control unit 110 performs processing for realizing and controlling various functions of the sound processing device 10. The control unit 110 enables the control unit 110 to execute a process instructed by an instruction (command) described in various programs such as an application program, and executes and controls the operation of each unit constituting the sound processing device 10. .. The control unit 110 includes, for example, one or more processors such as a CPU (Central Processing Unit).

The storage unit 130 stores various data used by the control unit 110, various data acquired by the control unit 110, various programs, and the like. The storage unit 130 includes, for example, a ROM (ReadOnlyMemory), a RAM (RandomAccessMemory), and the like.

The input / output unit 140 connects to a device separate from the sound processing device 10 by wire or wirelessly, and inputs / outputs various data. The input / output unit 140 may be connected to the communication network by wire or wirelessly, and may transmit and receive various data to and from a separate device connected to the communication network. The input / output unit 140 includes, for example, input / output devices such as an input / output interface and a communication interface.

Under the control of the control unit 110, the display unit 150 visually and recognizablely displays information instructed by various display data input from the control unit 110. Such display data includes image data, text data, and the like. The display unit 150 includes, for example, a display device of any form such as a liquid crystal display (LCD: Liquid Crystal Display) or an organic electro-luminescence display (OLED: Organic Electro-luminescence Display).

The operation unit 160 accepts the user's operation, generates an operation signal according to the accepted operation, and outputs the generated operation signal to the control unit 110. The operation signal indicates various information such as a user's instruction and a command to the sound processing device 10. The operation unit 160 includes, for example, an operation device in any form such as a push button or a stick key. The operation unit 160 may be configured to include a receiver that receives wirelessly (including infrared rays) from a physically separated operating device (eg, a remote controller).

Next, a functional configuration example of the sound processing device 10 according to the present embodiment will be described.
FIG. 4 is a schematic block diagram showing a functional configuration example of the sound processing device 10 according to the present embodiment. The sound processing device 10 includes a measurement control unit 112, a recording unit 114, and a calculation unit 116 in the control unit 110.

The measurement control unit 112 performs various controls related to the measurement of the head impulse response. When the operation signal indicating the start of measurement is input from the operation unit 160, the measurement control unit 112 generates a predetermined sound source signal for use in the measurement. The sound source signal is, for example, an impulse signal. The impulse signal is a signal whose signal value at a certain sample time is significantly different from zero (non-zero value) and whose signal value is zero at other times. The measurement control unit 112 outputs the sound source signal generated via the input / output unit 140 to the speaker Sp. The speaker Sp emits a sound according to the input sound source signal. The sample time when the signal value takes a non-zero value corresponds to the time when the impulse sound is emitted from the speaker Sp.

When the number of speakers Sp is a plurality as illustrated in FIG. 2, the measurement control unit 112 may specify the speaker Sp that emits sound as the output destination of the sound source signal. The speaker Sp as an output destination may be instructed by an operation signal input from the operation unit 160, or may be selected in a predetermined order.

The seat Pf may have a horizontal plane parallel to the floor surface and may have a rotatable seat plate. By rotating the subject Sb seated on the seat plate, the direction in the horizontal plane with the speaker Sp can be relatively changed. The subject Sb may operate the operation unit 160 to instruct the start of measurement each time the direction is changed by a predetermined angle (for example, 3 to 60 °). As a result, it is possible to easily measure HRIRs having different directions in the horizontal plane. The measurement control unit 112 acquires direction information indicating the direction of the seat Pf, outputs the acquired direction information to the calculation unit 116, and stores the acquired direction information in the storage unit 130 in association with the HRIR measured by the calculation unit 116. You may.

The recording unit 114 stores (records) the left sound receiving signal and the right sound receiving signal input from the microphones MicL and MicR via the input / output units 140, respectively.
The sounds directly or indirectly propagated from the speaker Sp arrive at the microphones MicL and MicR, respectively, and the incoming sounds are received. Therefore, the left sound receiving signal and the right sound receiving signal are input to the recording unit 114 from the microphones MicL and MicR, respectively. When an impulse signal is used as the sound source signal, the left-received signal and the right-received signal indicate HRIRs from the speaker Sp to the microphones MicL and MicR, respectively. Therefore, the recording unit 114 starts recording the left sound reception signal and the right sound reception signal when the operation signal indicating the start of measurement is input from the operation unit 160, and a predetermined recording period (for example, 0. Recording may be stopped after 2 to 2 seconds). The recording period may have a length of at least the above observation period or longer.

The calculation unit 116 inputs an operation signal indicating the start of measurement from the operation unit 160, and after the above recording period has elapsed, the calculation unit 116 reads the newly recorded sound reception signal from the recording unit 114. The arithmetic unit 116 acquires the HRIR from the read received signal. As described above, the reflected sound included in the observation period is significantly attenuated by the sound absorbing material As. However, the component of the reflected sound arriving after the above observation period may be left in the received signal.

Therefore, the arithmetic unit 116 may gradually attenuate (fade out) the signal value in the period after the observation period among the signal values forming the impulse response obtained from the received signal. For example, the calculation unit 116 attenuates the signal value of the received signal from the end point of the observation period over a predetermined attenuation time (for example, 10 to 100 ms) according to the passage of time until it reaches zero, and the time after that. Reject the signal value. Therefore, the influence of the reflected sound (hereinafter referred to as the late reflected sound) arriving after the observation period appearing in the received signal is removed, and the calculation unit 116 can acquire a significant portion as the HRIR. The components of the late reflected sound include, for example, the reflected sound from the ceiling, the back surface of the subject Sb, that is, the reflected sound from the seat Pf in the direction opposite to the direction of the speaker Sp. The calculation unit 116 stores the acquired HRIR signal indicating the HRIR in the storage unit 130.

Next, an example of the HRIR measurement process according to the present embodiment will be described.
FIG. 5 is a flowchart showing an example of the HRIR measurement process according to the present embodiment. However, before starting the following processing, the reflected sound for the impulses arriving at the microphones MicL and MicR attached to the left and right ears of the subject Sb arrives at least within the observation period from the generation of the impulse from the speaker Sp. The reflective material of the portion (that is, the floor surface, the wall surface, the seat Pf, etc.) is covered with the sound absorbing material As.

(Step S102) The measurement control unit 112 outputs an impulse signal to the speaker Sp. The speaker Sp emits an impulse as a measurement sound based on the impulse signal.
(Step S104) Each of the microphones MicL and MicR receives a sound arriving at its own unit, and acquires a left sound reception signal and a right sound reception signal indicating the received sounds, respectively. The microphones MicL and MicR output the left sound receiving signal and the right sound receiving signal to the recording unit 114, respectively.
(Step S106) The recording unit 114 records a left sound reception signal including an HRIR and a right sound reception signal, respectively.
(Step S108) The calculation unit 116 attenuates and rejects the signal values of the left-received signal and the right-received signal newly recorded in the recording unit 114 for a period after the observation period, thereby causing the late reflected sound. Is removed to obtain HRIR.

Note that the received signal may include noise coming from the surroundings to the microphone Mic. Therefore, the measurement control unit 112 may repeat the HRIR measurement process from step S102 to step S108 a predetermined number of times or more after the measurement start is instructed. As the number of repetitions, a predetermined number of times of two or more is set in advance in the measurement control unit 112. Therefore, the calculation unit 116 outputs the HRIR acquisition end notification to the measurement control unit 112 after each HRIR measurement process is completed. The measurement control unit 112 counts by adding (incrementing) the number of measurements by 1 each time the HRIR acquisition end notification is input. However, the initial value of the number of measurements is set to 0. Then, the measurement control unit 112 determines whether or not the number of measurements has reached the number of repetitions, and when it is determined that the number of measurements has reached, outputs a measurement end notification to the calculation unit 116. When the measurement control unit 112 determines that the value has not been reached, the measurement control unit 112 starts the next HRIR measurement process.

When the measurement end notification is input from the measurement control unit 112, the calculation unit 116 adds the signal values for each time included in the acquired HRIR signal for the number of repetitions between the repetitions of the HRIR measurement process for each time. A new HRIR signal including the sum obtained as a signal value is generated (synchronous addition). The arithmetic unit 116 may generate an HRIR signal including the quotient obtained by dividing the signal value related to each time by the number of repetitions as a new signal value instead of the original signal value (normalization). The calculation unit 116 stores the generated HRIR in the storage unit 130. By the synchronous addition, the noise component randomly superimposed during the repetition of the HRIR measurement process is relatively reduced as compared with the signal component of the HRIR. Therefore, the signal-to-noise ratio (SNR) is improved, and the influence of noise can be reduced.

<Second embodiment>
Next, the differences between the second embodiment and the first embodiment will be mainly described. Unless otherwise specified, the same components and processes as in the first embodiment are designated by the same reference numerals and the description thereof will be incorporated.

FIG. 6 is a side view showing a configuration example of the sound processing system 1 according to the present embodiment.
The sound processing system 1 according to the present embodiment includes a speaker Sp as a sound source, a microphone Mic L and Mic R as a sound receiving unit (however, Mic R is not shown in FIG. 6), a sound absorbing material As, and a sound processing device. In addition to 10, an image acquisition unit Cm is provided as an example of the measurement environment information acquisition unit. The image acquisition unit Cm takes an image of the measurement environment of the HRIR as an example of the measurement environment information. The image acquisition unit Cm is, for example, a digital still camera capable of capturing a still image. As a measurement environment, among the reflected sounds for the sound radiated from the speaker Sp, the area where the reflectors that bring about the reflected sounds that arrive in the microphones Mic L and Mic R within the observation period are distributed or arranged (hereinafter, evaluation area). ) May be included. In other words, the image acquisition unit Cm may be positioned and oriented so as to include the evaluation region in the visual field in the space Rm, and the viewing angle thereof may be set.

The sound processing device 10 determines the arrangement state of the sound absorbing material in the measurement environment, particularly in the evaluation region, based on the image taken by the image acquisition unit Cm. The sound processing device 10 estimates the reflection characteristic from the arrangement state with reference to the reflection characteristic-related data showing the relationship between the arrangement state and the reflection characteristic. Then, the sound processing device 10 determines whether or not to measure the HRIR based on whether or not the estimated reflection characteristic is more remarkable than the predetermined reflection intensity. This identifies whether or not the HRIRs that can be used to achieve a stereoscopic effect can be measured.

Next, a functional configuration example of the sound processing device 10 according to the present embodiment will be described. FIG. 7 is a schematic block diagram showing a functional configuration example of the control unit 110 provided in the sound processing system 1 according to the present embodiment.
The control unit 110 includes a measurement control unit 112, a recording unit 114, a calculation unit 116, a reflectance storage unit 124, and a measurement environment determination unit 126.

Reflectance characteristic-related data is stored in advance in the reflectance storage unit 124. The reflection characteristic-related data is data that includes information indicating the material and the reflectance for sound waves arriving at the material in association with each other for each material. Reflectance is the ratio of the intensity of the reflected wave to the sound wave to the intensity of the incoming sound wave. The reflection characteristic-related data may include information on a material that can be at least one type of sound absorbing material. The reflection characteristic-related data may or may not include information relating to a material that does not serve as a sound absorbing material. The sound absorbing material corresponds to a material having a reflectance sufficiently lower than a predetermined reflectance (for example, -30 to -50 dB).

Image data indicating an image taken from the image acquisition unit Cm is input to the measurement environment determination unit 126. The measurement environment determination unit 126 executes a predetermined image recognition process on the input image data to determine the arrangement state of the sound absorbing material in the measurement environment. More specifically, the measurement environment determination unit 126 identifies the material of the object arranged in the block for each block in which the image shown in the image data is subdivided into a predetermined size by the image recognition process. In the measurement environment determination unit 126, for example, image recognition data indicating the relationship between the image feature amount and the material is set in advance. In the image recognition process, the measurement environment determination unit 126 calculates, for example, the image feature amount for each block based on the pixel value of each pixel arranged in the block, and calculates by referring to the image recognition data. It is possible to specify the material of the subject corresponding to the image feature amount. Here, a set of blocks in which the specified material corresponds to the sound absorbing material corresponds to the sound absorbing material region, and the distribution of the sound absorbing material region indicates the arrangement state of the sound absorbing material.

The measurement environment determination unit 126 determines whether or not to measure the HRIR based on the arrangement information of the sound absorbing material. More specifically, the measurement environment determination unit 126 specifies the reflectance of the specified material for each block included in the evaluation region by referring to the reflection characteristic-related data, and the block in the evaluation region of the specified reflectance. The average value between them is calculated as the average reflectance. The measurement environment determination unit 126 determines whether or not to measure the HRIR based on whether or not the calculated average reflectance is equal to or less than a predetermined upper limit value (for example, -25 to -40 dB) of the reflectance. In the measurement environment determination unit 126, evaluation area information indicating an evaluation area in the captured image is set in advance. As described above, the evaluation area includes the positional relationship between the speaker Sp and the seat Pf, the distribution of reflectors (wall surface, side surface, seat Pf, etc.) of Rm in space, the position, orientation, and viewing angle of the image acquisition unit Cm. Determined based on size etc.

The measurement environment determination unit 126 generates, for example, display data including determination information corresponding to a determination result indicating whether or not to measure the HRIR, and outputs the generated display data to the display unit 150. As a result of the determination, the display unit 150 notifies the user whether or not the measurement environment is an appropriate environment, that is, an environment in which the HRIR can be sufficiently perceived by the listener. Here, the user may be an operator involved in the measurement of the HRIR, or may be the subject Sb himself.

The measurement environment determination unit 126 may output determination information indicating the determination result to the measurement control unit 112. When the determination information input from the measurement environment determination unit 126 indicates that the measurement control unit 112 measures the HRIR, the measurement control unit 112 executes the above-mentioned HRIR measurement process, and the determination information indicates that the measurement environment does not measure the HRIR. In the case of, it is not necessary to execute the above-mentioned HRIR measurement process. As a result, the measurement of HRIR is restricted when the measurement environment is not appropriate, and HRIR is measured when the measurement environment is appropriate. Therefore, the quality of the measured HRIR is ensured.

Next, an example of the measurement environment determination process according to the present embodiment will be described. FIG. 8 is a flowchart showing an example of the measurement environment determination process according to the present embodiment. However, the reflection characteristic-related data is saved in advance before the execution of the process shown in FIG. 8 is started. The reflection characteristic-related data includes information indicating the reflectance of each material.

(Step S202) The image acquisition unit Cm captures an image of the measurement environment and outputs image data indicating the captured image to the sound processing device 10.
(Step S204) The measurement environment determination unit 126 performs image recognition processing on the image data input from the image acquisition unit Cm, and the subject in the measurement environment represented in the field of view for each block in which the image is subdivided. Identify the material. The measurement environment determination unit 126 determines the reflectance of the material specified for each block with reference to the reflection characteristic-related data.

(Step S206) The measurement environment determination unit 126 determines the average reflectance as an example of the representative value of the reflectance in the evaluation region based on the reflectance determined for each block in the predetermined evaluation region. The measurement environment determination unit 126 determines whether or not the determined average reflectance is equal to or less than the upper limit of the predetermined reflectance. The measurement environment determination unit 126 determines that the measurement environment measures HRIR when it is determined that the average reflectance is equal to or less than the upper limit value, and when it is determined that the average reflectance is larger than the upper limit value, the measurement environment is HRIR. Is determined not to be measured.
The measurement environment determination unit 126 may output the determination information indicating the determination result to the display unit 150 or the measurement control unit 112.

In addition, when the measurement environment determination unit 126 determines whether or not the measurement environment is an environment for measuring HRIR, as an example of an index of the arrangement state of the sound absorbing material, a case where the reflectance in the evaluation region is determined is taken as an example. , Not limited to this. For example, the measurement environment determination unit 126 may determine the coverage of the sound absorbing material of a predetermined material in the evaluation region as an example of the index of the arrangement state of the sound absorbing material. Here, in the measurement environment determination unit 126, sound absorbing material information indicating whether or not the member is a sound absorbing material may be set in advance for each member. In that case, it is not necessary to store the reflection characteristic-related data in advance in the reflectance storage unit 124.

The measurement environment determination unit 126 performs image recognition processing on the image data as described above, and identifies the material of the subject for each block. The measurement environment determination unit 126 can specify whether or not the identified material is a sound absorbing material by referring to the sound absorbing material information set in the own unit. The measurement environment determination unit 126 determines a set of blocks in which the specified material is determined as the sound absorbing material as the sound absorbing region. The measurement environment determination unit 126 can calculate the ratio of the area of the sound absorbing region included in the evaluation region to the area of the evaluation region as the sound absorbing region ratio. Then, the measurement environment determination unit 126 determines whether or not the sound absorption region ratio is equal to or higher than the lower limit of the predetermined ratio (for example, 0.8 to 0.98) as an index value indicating the arrangement state of the sound absorbing material. When the measurement environment determination unit 126 determines that the sound absorption region ratio is equal to or higher than a predetermined lower limit, the measurement environment determines that the HRIR is measured, and when the measurement environment determines that the sound absorption region ratio is equal to or less than the predetermined lower limit, the measurement environment determines the HRIR. Judge as an environment not to be measured.

Next, an example of the configuration of the above embodiment will be described. FIG. 9 is an explanatory diagram showing an example of the configuration. The sound processing system 1 according to the above embodiment includes a sound source (for example, a speaker Sp), a sound receiving unit (for example, a microphone Mic), a calculation unit 116, and a sound absorbing material As. The sound source emits a sound based on a predetermined sound source signal. The sound receiving unit acquires a sound receiving signal of the incoming sound. The arithmetic unit 116 acquires an impulse response from the sound source to the sound receiving unit from the acquired sound receiving signal. The sound absorbing material covers an object on the path of reflected sound that arrives at least within a predetermined observation period from the generation of sound.
According to this configuration, the installation of the sound absorbing material reduces the intensity of the reflected sound component that arrives at least within the observation period in the impulse response as compared with the case where the sound absorbing material is not installed. Further, it is sufficient that the sound absorbing material is covered with an object related to the propagation path of the reflected sound arriving within at least the observation period in the propagation path of the sound wave from the sound source to the sound receiving portion. Therefore, even in an ordinary space that does not have special equipment such as an anechoic chamber, it is possible to easily obtain an impulse response to be used as an HRIR. Here, the load related to the installation of the sound absorbing material is relatively light, and the space can be effectively utilized.

Further, the arithmetic unit 116 may attenuate the signal value after the observation period of the acquired impulse response has elapsed.
According to this configuration, the portion of the acquired impulse response within the observation period is extracted, and the portion after the lapse of the observation period is removed. Therefore, the important part of the HRIR during the observation period for perceiving the three-dimensional effect of the sound is maintained, and the influence of the late reflected sound that arrives after the observation period can be avoided.

Further, the acoustic processing system 1 may include a measurement control unit 112 that repeats the generation of sound from the sound source, the acquisition of the received signal, and the acquisition of the impulse response a plurality of times. The arithmetic unit 116 may synchronously add a plurality of acquired impulse responses.
According to this configuration, the added noise component is relatively reduced as compared with the component of the impulse response added by the synchronous addition. Therefore, it is possible to obtain a more accurate impulse response.

Further, the sound processing system 1 may include a measurement environment information acquisition unit (for example, an image acquisition unit Cm) and a measurement environment determination unit 126. The measurement environment information acquisition unit acquires information on the measurement environment of the impulse response. The measurement environment determination unit refers to the preset reflection characteristic-related data, determines the arrangement state of the sound absorbing material based on the acquired information, and the measurement environment measures the impulse response based on the determined arrangement state of the sound absorbing material. Determine whether or not to do so.
According to this configuration, it is determined based on the arrangement state of the sound absorbing material whether the measurement environment is an appropriate environment capable of obtaining an impulse response that allows the listener to sufficiently perceive a three-dimensional effect, and the determination thereof. The necessity of measuring the impulse response is determined according to the result. Therefore, the acquisition of an inappropriate impulse response is restricted, and the acquisition of an appropriate impulse response is promoted.

Further, the sound processing system 1 may include a reflectance storage unit 124. The reflectance storage unit 124 stores reflection characteristic-related data including information associated with information on the material and the reflectance of sound. The measurement environment determination unit 126 identifies the material of the subject specified from the image as the acquired information, refers to the reflection characteristic-related data, specifies the reflectance corresponding to the specified material, and is based on the specified reflectance. To determine whether to measure the impulse response.
According to this configuration, the material of the subject represented in the acquired image is specified, and it is determined whether or not to measure the impulse response based on the reflectance specified from the specified material. Therefore, since the reflectance in the measurement environment of the impulse response is estimated without performing the actual measurement, it is determined whether or not the impulse response can be measured without any change in the acoustic environment due to the actual measurement.

Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope of the invention described in the claims and the equivalent scope thereof, as are included in the scope and gist of the invention.

This application claims priority based on Japanese Patent Application No. 2020-156368 filed on September 17, 2020, and incorporates all of its disclosures here.

The present invention may be applied to an acoustic processing system, an acoustic processing method, and a recording medium.

1 ... Sound processing system 10 ... Sound processing device 110 ... Control unit 112 ... Measurement control unit 114 ... Recording unit 116 ... Calculation unit 124 ... Reflectance storage unit 126 ... Measurement environment determination unit 130 ... Storage unit 140 ... Input / output unit 150 ... Display unit 160 ... Operation unit As ... Sound absorbing material Cm ... Image acquisition unit Mic (Mic L, Mic R) ... Microphone Sp ... Speaker

Claims

A sound source that emits sound based on a predetermined sound source signal,
A sound receiving unit that acquires the sound receiving signal of the incoming sound,
An arithmetic unit that acquires an impulse response from the sound receiving signal to the sound receiving unit, and
An acoustic processing system comprising a sound absorbing material that covers an object on the path of the reflected sound arriving at the sound receiving portion within at least a predetermined observation period from the generation of the sound.
The arithmetic unit
The acoustic processing system according to claim 1, wherein the signal value of the impulse response after the lapse of the observation period is attenuated.
It is provided with a measurement control unit that repeats the generation of sound from the sound source, the acquisition of the received signal, and the acquisition of the impulse response a plurality of times.
The arithmetic unit
The acoustic processing system according to claim 1 or 2, wherein the plurality of impulse responses are synchronously added.
A measurement environment information acquisition unit that acquires information on the measurement environment of the impulse response,
Based on the information, the arrangement state of the sound absorbing material in the measurement environment is determined.
The invention according to any one of claims 1 to 3, further comprising a measurement environment determination unit for determining whether or not to measure the impulse response based on the arrangement state with reference to preset reflection characteristic-related data. Sound processing system.
It is provided with a reflectance storage unit that stores the reflection characteristic-related data associated with the material and sound reflectance information.
The measurement environment determination unit is
The material of the subject specified from the image is specified as the information, and the reflectance corresponding to the specified material is specified by referring to the reflection characteristic-related data.
The acoustic processing system according to claim 4, wherein it is determined whether or not to measure the impulse response based on the specified reflectance.
It is an acoustic processing method for an acoustic processing system including a sound absorbing material that covers an object on the path of the reflected sound that arrives at the sound receiving portion within at least a predetermined observation period from the generation of sound from the sound source.
The first step in which the sound source emits a sound based on a predetermined sound source signal,
The second step in which the sound receiving unit acquires the sound receiving signal of the incoming sound, and
An acoustic processing method comprising a third step in which an arithmetic processing unit acquires an impulse response from the sound source to the sound receiving unit from the sound receiving signal.
A computer of an acoustic processing system comprising a sound absorbing material covering an object on the path of reflected sound arriving at a sound receiving unit at least within a predetermined observation period from the generation of sound from a sound source.
The first step in which the sound source emits a sound based on a predetermined sound source signal,
The second step in which the sound receiving unit acquires the sound receiving signal of the incoming sound, and
The third step in which the arithmetic processing unit acquires an impulse response from the sound source to the sound receiving unit from the sound receiving signal,
A recording medium that stores a program to execute.