JP2009253526A - Sound field controller and sound field controlling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound field controller which can keep a specified direction of sound even if a listener rotates his/her head. <P>SOLUTION: The sound field controller selects two or more loudspeakers 38 among a plurality of optionally-arranged loudspeakers 38 by a loudspeaker selection and filter changing section 34 in response to the specified direction of original sound to a listener, and it adjusts acoustic pressure balance of the selected loudspeaker 38 by a balancing section 36 so that the acoustic pressure balance may match with the normal-position direction of the original sound. Furthermore, it uses the selected loudspeaker 38 to select a filter for controlling the acoustic state near both ears of the listener by the loudspeaker selection and filter changing section 34, and it outputs sound filtered by using the selected filter in a filtering section 35 through the selected loudspeaker 38. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sound field control apparatus and a sound field control method for reproducing a sound localization direction and distance using a plurality of arbitrarily arranged speakers.

Conventionally, as a sound field control technique for reproducing the sound localization direction and distance using a plurality of arbitrarily arranged speakers, even if the position of both ears of the listener is changed, it is not easily affected. Thus, a technique for improving the sound localization has been proposed (see, for example, Patent Document 1). Specifically, this Patent Document 1 is robust against displacement of the listening position by selecting two speakers from a plurality of sound sources and performing sound field control using only these two speakers. A system is disclosed.
JP 2002-127854 A

  However, in the conventional technique described in Patent Document 1 described above, when the listener turns his head in a direction parallel to the line connecting the two speakers, a sense of sound localization can be obtained. There was a problem that it was impossible.

  Therefore, the present invention has been proposed in view of the above-described circumstances, and a sound field control device and sound that can maintain the sound localization direction even when the listener rotates the head. An object is to provide a field control method.

  The present invention selects two or more speakers to be used from among a plurality of speakers arbitrarily arranged according to the localization direction of the original sound with respect to the listener, and the sound pressure balance of the selected speakers is determined based on the localization of the original sound. The filter is adjusted so as to match the direction, and a filter that controls the sound state near the ears of the listener is selected using the selected speaker, and the sound source signal is filtered by the filter, and the selected speaker is To solve the above-mentioned problems.

  According to the present invention, the sound localization direction can be maintained even when the listener rotates his / her head by setting a speaker that outputs sound, a sound pressure balance, and a filter in an optimal combination. Can do.

  Hereinafter, a sound field control device as a preferred embodiment of the present invention will be specifically described.

[Configuration of sound field control device]
The sound field control device shown as an embodiment of the present invention accurately reproduces the sound localization direction and distance by controlling the sound state near the ears of the listener using a plurality of arbitrarily arranged speakers. Therefore, the present invention is suitable for a system that presents a notification sound having a specific localization direction to the driver in the passenger compartment.

  In a general transoral system, for example, as shown in FIG. 1, a binaurally recorded virtual sound source S is input to an inverse filter matrix 11 and output through a speaker 12. The plurality of speakers 12 are often arranged adjacent to each other. At this time, the transoral system can listen to the sound image only when the listener A has both ears at the control point position. For example, when this transoral system is applied to a vehicle, the listener A can hear the engine sound as the sound image I in the right direction. At this time, the listener B who is not located at the control point position cannot feel the localization of the sound image, but simply hears that the engine sound having the same content as the sound image is sounding all around.

  Here, it is desired that the sound image position does not change even when the listener's head rotates. For example, as shown in FIG. 2, it is desired that the position of the sound image I continues to be heard backward even when the listener A faces the left rear.

  Therefore, in the sound field control apparatus shown as an embodiment of the present invention, the distance and direction of the sound image I are maintained when the listener A is facing the front, and only the direction is sensed when the head is rotated. Control to be held.

  Schematically, as shown in FIG. 3, the sound field control device inputs the binaurally recorded virtual sound source S to the filter matrix 21 with switching, and inputs the output of the filter matrix 21 to the balancer 22 to input the speaker 23. The sound is output by the speaker 23 after adjusting the sound pressure balance.

  Here, the input sound (original sound) is a sound having a specific localization direction in advance. That is, it is necessary to include not only the sound field control device itself but the direction in which the sound image is arranged in advance in the sound input as the prior information. The filter matrix 21 with switching selects an inverse filter using only the speaker 23 to be used from among the plurality of speakers 23, and outputs timing, phase, sound pressure, etc. of the sound output from the speaker 23 using the selected filter. To control. Since it is difficult to dynamically design the inverse filter, the inverse filter is designed in advance in the sound field control device under the condition of the sound pressure balance by the balancer 22 shown below.

  That is, the balancer 22 changes the sound pressure level of the sound source signal supplied from the switched filter matrix 21 to the same balance as when the transfer characteristic for creating the inverse filter is measured. This balance is determined for each speaker 23 and inverse filter selected by the filter matrix 21 with switching.

  When the speakers 23 are arranged in a balanced manner for the listener and the number of speakers 23 is aligned in a specific direction, the sound field control device matches the sound pressure levels of all sound sources. Also good. On the other hand, as shown in FIG. 2, the sound field control device may extremely adjust the balance of the sound output from each speaker 23 when the arrangement positions of the selected speakers 23 are wide. Good.

  In FIG. 3, among the four speakers 23, the output of the speaker 23 positioned at the right front of the listener is maximized, and the output of the speaker 23 positioned at the right rear of the listener is second largest. The balance of the sound output from each speaker 23 is extremely set so that the output of the speaker 23 located at the left front of the listener is third largest and the output of the speaker 23 located at the left rear of the listener is zero. The state of adjustment is represented by the thickness of the arrow. Such a sound pressure level difference can theoretically be removed by an inverse filter. However, when a speaker 23 having a greatly different dynamic range is used in an actual environment, the difference is not necessarily removed. The effect remains. Therefore, the listener can feel the sound image I in the right direction as shown in FIG.

  The sound field control device that realizes such sound field control is specifically configured as shown in FIG. That is, the sound field control device includes a sound source generation unit 31 that generates a sound source, a sound source direction detection unit 32 that detects the direction of the sound source generated by the sound source generation unit 31, and a filter storage unit that stores data of an inverse filter. 33, a speaker selection / filter switching unit 34 that selects the speaker 38 to be used and switches the inverse filter, a filter processing unit 35 that performs inverse filtering processing on the input sound source signal, and a speaker selection / filter switching unit 34. A balance unit 36 that adjusts the sound pressure balance of the speaker 38 and an amplifier 37 that amplifies the sound and outputs the amplified sound through the speaker 38.

  The sound source generator 31 generates a sound source signal as an original sound input to the sound field control device. Specifically, as shown in FIG. 5, the sound source generator 31 collects sound using a head and torso simulator (HATS), a dummy head, or the like, and binaurally records the sound source signal. As shown in FIG. 6, a sound source signal is generated as a virtual sound source that adds spatial information by a head related transfer function (HRTF) to a sound to be placed at an arbitrary position. Here, as described above, the original sound generated by the sound source generation unit 31 is a sound having a specific localization direction in advance, such as a virtual sound source. Therefore, it is desirable that the sound source generation unit 31 generates a sound source signal having sound source information and sound source direction information indicating the direction of the sound source. The sound source signal having the sound source information and the sound source direction information generated by the sound source generation unit 31 is supplied to the sound source direction detection unit 32.

  The sound source direction detection unit 32 detects the direction of the sound source (original sound) based on the sound source direction information of the sound source signal supplied from the sound source generation unit 31. Specifically, when the sound source signal itself includes sound source direction information, the sound source direction detecting unit 32 detects the direct direction from the sound source signal, and from text data or the like corresponding to the sound source information. If the sound source direction information is separately provided, the direction of the sound source is detected based on the sound source direction information. That is, when the sound source is a virtual sound source, the sound source direction detection unit 32 may detect the sound source direction information as it is because the direction to be presented in advance is determined by a sensor or the like. Further, since the sound source direction detection unit 32 needs to detect the direction of the sound source and adjust the balance of the speaker 38 when the sound source is binaurally recorded, a direction detection algorithm such as a so-called delay sum array ( The direction of the sound source is detected using Oga, Yamazaki, Kanada, "Sound System and Digital Processing", IEICE pp181-186), etc. The sound source direction detection unit 32 supplies the detected sound source direction information to the speaker selection / filter switching unit 34 and also supplies the virtual sound source information to the filter processing unit 35.

  The filter storage unit 33 stores inverse filter data created for each of the plurality of speakers 38. The inverse filter data stored in the filter storage unit 33 is read by the speaker selection and filter switching unit 34.

  The speaker selection / filter switching unit 34 selects the speaker 38 to be used based on the sound source direction information supplied from the sound source direction detection unit 32. In particular, as will be described later, the speaker selection and filter switching unit 34 selects two or more speakers 38 arranged in a small angle range from the center angle with the sound source direction as the center, among the plurality of speakers 38. Then, the speaker selection and filter switching unit 34 reads out the data of the inverse filter that controls the sound state in the vicinity of the listener's both ears from the filter storage unit 33 using the selected speaker 38 and switches the inverse filter to be used. The speaker selection / filter switching unit 34 supplies information indicating the selected speaker 38 to the balance unit 36 and supplies data of the selected inverse filter to the filter processing unit 35.

  The filter processing unit 35 performs reverse filtering processing on the virtual sound source information supplied from the sound source direction detection unit 32 using the data of the inverse filter supplied from the speaker selection and filter switching unit 34. Specifically, the filter processing unit 35 performs an inverse filtering process using an inverse matrix, a norm minimum solution, or a Gaussian elimination method. At this time, when the sound source is a virtual sound source, the filter processing unit 35 performs a reverse filtering process using the sound source direction information as it is because the direction to be presented in advance is determined by a sensor or the like. The filter processing unit 35 supplies virtual sound source information as a sound source signal subjected to inverse filtering processing to the balance unit 36.

  The balance unit 36 adjusts the sound pressure balance of the speaker 38 selected by the speaker selection and filter switching unit 34 so as to match the localization direction of the original sound. That is, the balance unit 36 changes the sound pressure level of the virtual sound source information supplied from the filter processing unit 35 to the same balance as when the transfer characteristic for creating the inverse filter is measured, so that the sound of the speaker 38 to be used is changed. Adjust the pressure balance. This sound pressure balance is determined for each speaker 38 and inverse filter selected by the speaker selection and filter switching unit 34. When the speakers 38 are arranged in a balanced manner with respect to the listener and there are a sufficient number of speakers 38 as described later, the balance unit 36 matches the sound pressure levels of all the sound sources. It may be. The balance unit 36 supplies virtual sound source information in which the sound pressure balance of each speaker 38 is adjusted to the amplification unit 37.

  The amplifying unit 37 amplifies a sound composed of an analog signal obtained by D / A converting the virtual sound source information supplied from the balance unit 36 with a predetermined gain, and outputs the amplified sound via a speaker 38.

[Operation of sound field control device]
In such a sound field control device, the speaker selection and filter switching unit 34 selects the speaker 38 to be used as follows.

  In general, it is desirable to arrange the speakers in the trans-oral system on the left and right with respect to the median plane of the listener. This is because the sound in the front-rear direction can be configured with a phase difference, while the sound pressure level is used as information for obtaining a sense of localization in order to create left and right sounds. Due to being.

  However, the inventor of the present application, for a sound source that is apparently output from a specific direction in advance, such as a virtual sound source, simply arranges the sound source in that direction and accurately sets the direction of the sound image in that direction. It has been found that it is possible to configure, and the distance of the sound image can also be configured substantially accurately.

  Therefore, in the sound field control device, based on such knowledge, only when a sound source exists in a specific direction, two or more speakers 38 arranged in a small angle range from the central angle with the sound source direction as the center. Is selected by the speaker selection and filter switching unit 34, and the filtering process is performed by the filter processing unit 35 with the speaker 38.

  Specifically, the speaker selection and filter switching unit 34 includes, for example, eight speakers 38a, 38b, 38c, 38d, 38e, 38f, 38g, and 38h around the listener as shown in FIG. In the case where the sound source is present at the right front of the listener, the speaker 38a disposed at the front of the listener, the speaker 38b disposed at the right front, and the right Three speakers of the arranged speaker 38c are selected as speakers to be used.

  In the speaker selection / filter switching unit 34, for example, as shown in FIG. 7B, eight speakers 38a, 38b, 38c, 38d, 38e, 38f, 38g, and 38h are arranged around the listener. If the sound source is in the right front of the listener and is located on the right side of the position shown in FIG. 7A, the speaker 38b disposed on the right front side and the right side Are selected as speakers to be used.

  Further, as shown in FIG. 7C, for example, the speaker selection and filter switching unit 34 is provided with eight speakers 38a, 38b, 38c, 38d, 38e, 38f, 38g, and 38h around the listener. If the sound source is present on the right side of the listener, the speaker 38b disposed on the right front side, the speaker 38c disposed on the right side, and the rear right side are disposed. The three speakers 38d are selected as speakers to be used.

  Accordingly, in the sound field control device, by setting the speaker 38 that outputs sound, the sound pressure balance, and the filter in an optimal combination, a) at the listening position where the control area and the listener's binaural position match. Achieving a sense of localization of the sound image I and b) obtaining a sense of localization regarding the direction of the sound image I even when the listener's head rotates and the control area and the position of both ears do not coincide. can do.

  In such a sound field control device, the sound source is reproduced according to a series of procedures as shown in FIG.

  First, as shown in FIG. 8, when the system is initialized in step S1, the sound field control device detects whether or not a sound source is input from the sound source generation unit 31 in step S2.

  Subsequently, when the sound field control device detects the input of the sound source, in step S3, the sound source direction detection unit 32 detects the direction of the sound source based on the sound source direction information of the sound source signal.

  Subsequently, in step S4, the sound field control device changes the sound pressure balance of the speaker 38 by the balance unit 36 based on the direction of the sound source detected in step S3, and further, the speaker selection and filter switching unit 34. Thus, the speaker 38 to be output is determined and the content of the inverse filter is switched.

  Then, in step S5, the sound field control device performs inverse filtering processing on the sound source signal by the filter processing unit 35, and in step S6, the sound source signal obtained is D / A converted to generate a sound composed of an analog signal. Amplification unit 37 amplifies the signal with a predetermined gain, outputs the signal via speaker 38, and ends the series of processes.

  In the sound field control device, according to such a series of procedures, the sound source can be reproduced while maintaining the sound localization direction.

  Such a sound field control device is extremely effective when applied to a system that presents a notification sound to a driver using a large number of speakers distributed in a vehicle interior. Such a system can reliably present a notification sound having a specific localization direction to the driver even during driving that easily rotates the head.

[Effect of the embodiment]
As described above in detail, the sound field control device shown as an embodiment of the present invention uses two speakers 38 that are used among a plurality of speakers 38 that are arbitrarily arranged according to the localization direction of the original sound to the listener. The above speaker 38 is selected by the speaker selection / filter switching unit 34, the sound pressure balance of the selected speaker is adjusted by the balance unit 36 so as to coincide with the localization direction of the original sound, and the listener is used by using the selected speaker. A filter for controlling the sound state near both ears is selected by the speaker selection and filter switching unit 34, and the sound filtered by using the selected filter is output via the selected speaker 38.

  Thereby, in this sound field control device, the listener can be allowed to move the head, and the sound localization direction can be maintained even when the head is rotated. In this sound field control device, up to ± 180 ° can be allowed in principle with respect to the localization direction. Further, in this sound field control device, it is possible to select two or more speakers 38 and output sound depending on the direction of the sound source. The orientation is not lost even if the head is turned.

  In addition, the sound field control device generates a sound source signal as an original sound having a specific localization direction in advance by the sound source generation unit 31, and detects the direction of the original sound from the generated sound source signal by the sound source direction detection unit 32. Since the speaker 38 to be used is selected by the speaker selection and filter switching unit 34 based on the direction of the original sound, the sound can be output depending on the sound source direction, and even if the listener rotates the head The direction of sound localization can be maintained.

  Furthermore, when the sound source signal itself includes sound source direction information indicating the direction of the original sound, the sound field control device detects the direction directly from the sound source signal by the sound source direction detection unit 32 and corresponds to the original sound. When the sound source direction information indicating the direction of the original sound is given, the direction of the original sound can be reliably detected by detecting the direction from the sound source direction information, and the speaker selection and filter switching unit An appropriate speaker 38 can be selected by 34.

  Furthermore, this sound field control device uses a speaker selection and filter switching unit 34 to select two or more speakers 38 arranged in a small angle range from the central angle with the direction of the original sound as a center. By selecting a sound source that is clearly output from a specific direction in advance, the direction of the sound image in that direction can be accurately configured only by arranging the sound source in that direction.

  In addition, the sound field control device balances the sound pressure level of the sound output from the speaker 38 selected by the speaker selection / filter switching unit 34 with the same balance as when the transfer characteristic for creating the inverse filter is measured. By adjusting with 36, an inverse filter that is difficult to design dynamically can be easily designed.

  The above-described embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and even if it is a form other than this embodiment, as long as it does not depart from the technical idea according to the present invention, the design and the like Of course, various modifications are possible.

It is a figure shown about the structure of a general trans-oral system. It is a figure shown about the structure of the trans-oral system which wants to implement | achieve with this invention. It is a figure showing roughly about composition of a sound field control device shown as an embodiment of the present invention. It is a block diagram shown about the structure of the sound field control apparatus shown as embodiment of this invention. It is a figure for demonstrating the sound source signal which carried out binaural recording. It is a figure for demonstrating the sound source signal as a virtual sound source. (A) is a figure shown about the example of selection of a speaker in case a sound source exists in the listener's right front, (B) is a listener's right front of a listener, and is a right side rather than the position shown to (A). It is a figure shown about the example of selection of the speaker in the case where it exists near, and (C) is a figure shown about the example of selection of the speaker when the sound source exists in the listener's right side. It is a flowchart which shows a series of procedures at the time of reproducing | regenerating a sound source by the sound field control apparatus shown as embodiment of this invention.

Explanation of symbols

11 Inverse filter matrix 12, 23, 38, 38a, 38b, 38c, 38d, 38e, 38f, 38g, 38h Speaker 21 Filter matrix with switching 22 Balancer 31 Sound source generation unit 32 Sound source direction detection unit 33 Filter storage unit 34 Speaker selection and Filter switching unit 35 Filter processing unit 36 Balance unit 37 Amplifying unit A, B Listener I Sound image S Virtual sound source

Claims (6)

A plurality of arbitrarily arranged speakers;
Speaker selection means for selecting two or more speakers among the plurality of speakers according to the localization direction of the original sound with respect to the listener;
Adjusting means for adjusting the sound pressure balance of the speaker selected by the speaker selecting means so as to coincide with the localization direction of the original sound;
Filter selection means for selecting a filter for controlling a sound state near both ears of the listener using the speaker selected by the speaker selection means;
A sound field control apparatus comprising: control means for performing a filtering process on a sound source signal using a filter selected by the filter selection means and outputting sound from the speaker selected by the speaker selection means. Sound source generating means for generating a sound source signal as the original sound having a specific localization direction in advance;
Sound source direction detecting means for detecting the direction of the original sound from the sound source signal generated by the sound source generating means,
The sound field control device according to claim 1, wherein the speaker selection unit selects a speaker to be used based on the direction of the original sound detected by the sound source direction detection unit.   The sound source direction detecting means detects the direction directly from the sound source signal when the sound source signal itself includes sound source direction information indicating the direction of the original sound, and determines the direction of the original sound corresponding to the original sound. The sound field control device according to claim 2, wherein the direction is detected from the sound source direction information when the sound source direction information is provided.   The said speaker selection means selects two or more speakers arrange | positioned in the angle range small from a center angle centering | focusing on the direction of the said original sound among these speakers. Sound field control device.   The adjusting means adjusts the sound pressure level of the sound output from the speaker selected by the speaker selecting means to the same balance as when a transfer characteristic for creating an inverse filter is measured. The sound field control device described in 1. Two or more speakers to be used are selected from a plurality of speakers arbitrarily arranged according to the localization direction of the original sound with respect to the listener, and the sound pressure balance of the selected speakers is matched with the localization direction of the original sound. And selecting a filter that controls the sound state near the ears of the listener using the selected speaker,
A sound field control method comprising: filtering a sound source signal with a selected filter and outputting the filtered signal through a selected speaker.

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