JP2009253948A - Sound reproducing device and sound reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound reproducing device capable of localizing two sound sources at different positions even on a straight line connecting two sets of loudspeakers and localizing the two sound sources at the different positions in a wide range centering on the sound reproducing device. <P>SOLUTION: The sound reproducing device includes first and second reproducing units, and reproduces two input channel signals (first and second input channel signals). The first reproducing unit receives the first input channel signal as the input signal, and includes two first loudspeakers disposed so that the sound-emitting directions are mutually opposite, a first phase inverter for making the phases of two input signals mutually reversed, and a first level converter for giving a level difference. The second reproducing unit is disposed at a position different from that of the first reproducing unit, receives the second input channel signal as the input signal, and includes two second loudspeakers disposed so that the sound-emitting directions are mutually opposite, a second phase inverter for making the phases of two input signals mutually reversed, and a second level converter for giving a level difference. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sound reproducing apparatus and a sound reproducing method which are used for, for example, a telephone conference and reproduce a two-channel audible band signal with a plurality of speakers.

  A sound reproduction device that reproduces a two-channel audible band signal used in a teleconference system or a video conference system with a plurality of speakers, and determines the position of the sound image that the listener can hear by making a difference in the signals output from the plurality of speakers. Can be changed. By localizing a plurality of reproduced sound images at different positions, it becomes possible to improve the intelligibility of each sound source.

  FIG. 1 shows the most basic configuration of an acoustic reproduction apparatus that reproduces a two-channel signal by a plurality of speakers. There is one speaker for reproducing two-channel signals. A sound image can be localized between two speakers by giving a level difference or a time difference to the input signals of two channels. However, the listener is forced to be located at the same distance from the two speakers. When deviating from this position, all sounds are localized at the position of one speaker, and when a plurality of sounds are reproduced, improvement of the intelligibility of the sound source due to being heard from different positions cannot be expected. Therefore, the listening position where the clarity of a plurality of sound sources can be maintained is extremely narrow.

Non-Patent Document 1 discloses a method for enlarging a listening position by localizing a sound image to a different position. This technique will be described with reference to FIG. Two-channel input signal Ch. 1 and Ch. Two speakers S _L1 , S _L2 and S _R1 , S _R2 are installed at the left and right speaker positions where 2 is input, respectively. The directivity of the speakers S _L1 and S _R1 located outside each set is in the front direction, and the directivity of the speakers S _L2 and S _R2 located inside is the listener B located in the center front of the two sets of speakers. Is directed to.

The listener A located in front of the left speaker S _L1 listens to the sounds of the speakers S _L1 and S _R2 . Since the distance between the listener A and each of the speakers S _L1 and S _R2 is farther from the speaker S _R2 , the delay unit 70 _L is connected in series to the input side of the speaker S _L1 , and the sound is transmitted through the far distance. Input signal Ch. 2 is delayed by the delayer 70 _L. In addition, an amplifier 72 _R for compensating for the corresponding decrease in sound pressure is provided on the input side of the speaker S _R2 far from the listener A so that the listener A can hear the sounds of the speakers S _L1 and S _{R2 at} the same volume. Connected in series. By doing in this way, it is possible for the listener A located in front of the left speaker S _L1 to obtain a good sound image localization. The listener B positioned at the center of the two sets of speakers hears the sounds of the speakers S _L2 and S _R2 that are not delayed from each other at the same time. The input side of the speaker _{S R1,} delayer 70 _R corresponding to the delay device 70 _L are connected in series to the input side of the speaker _{S L2,} an amplifier 72 _L corresponding to the amplifier 72 _R are connected in series Yes. Therefore, the listener C positioned in front of the right speaker S _R1 listens to the sounds of the speakers S _R1 and S _L2 , and can obtain a good sound image localization on the same principle as the listener A side. Thus, the listening area can be expanded in a direction parallel to the speaker arrangement direction.

  Another method for enlarging the listening position is shown in Non-Patent Document 2. This technique will be described with reference to FIG. In this method, the sound image is not localized between the speaker L and the speaker R, but Ch. 1 sound signal from the speaker R, Ch. 2 sound signals are reproduced from the speaker L, respectively. For this purpose, both channels Ch. 1, Ch. When a signal is mixed with 2, a crosstalk canceller 80 is used to remove the signal. Therefore, in this method, the input Ch. 1 and Ch. Each of the two sound sources is fixed and reproduced at either position of the speaker L or R.

In these conventional techniques, the listening area can be expanded in a direction parallel to the direction in which the speakers are arranged.
Toshiro Oga, Yoshio Yamazaki, Yutaka Kaneda "Sound System and Digital Processing", 1995, pp. 232-233. Takahiro Oyama, Haruhide Hokari, Masaharu Shimada “Comparison of sound source separation methods used for multi-listener loudspeaker communication”, IEICE Journal (A), Vol. J86-A No. 7, 2003.

  However, in the conventional method, when the localization of a plurality of sound sources is localized at different positions, the position of the listener is limited. In particular, if the listener is located near the extended line connecting the two sets of speakers, the plurality of sound sources cannot be localized at different positions. That is, the listener on the extended line connecting the two sets of speakers can hear the sound of the channel signals from the two sound sources from the same direction.

  The present invention has been made in view of such a problem, and even a listener on a linear extension line connecting two sets of speakers can localize sound images for two sound sources at different positions. An object is to provide an apparatus and a sound reproduction method.

  The sound reproducing device of the present invention reproduces two input channel signals (a first input channel signal and a second input channel signal). This sound reproduction apparatus includes a first reproduction unit and a second reproduction unit.

  The first reproduction unit uses the first input channel signal as an input signal and reverses the phases of the two first speakers arranged so that the sound output directions are opposite to each other and the input signals to the two first speakers. And a first level converter that gives a level difference to the input signals to the two first speakers. The second reproduction unit is arranged at a position different from the first reproduction unit, and uses the second input channel signal as an input signal and two second speakers arranged so that the sound emission directions are opposite to each other, A second phase inverter that reverses the phases of the input signals to the two speakers, and a second level converter that gives a level difference between the input signals to the two second speakers.

  Alternatively, the first reproduction unit uses the first input channel signal as an input signal, and sets the phase of the two first speakers arranged so that the sound emission directions are opposite to each other and the two input signals to the first speaker. A first phase inverter is provided that reverses each other. The second reproduction unit is arranged at a position different from the first reproduction unit, and uses the second input channel signal as an input signal and two second speakers arranged so that sound emission directions are opposite to each other, A second phase inverter that reverses the phases of the input signals to the second speaker; A line connecting the center of the two speakers of the first reproduction unit and the center of the two speakers of the second reproduction unit and a direction perpendicular to the sound emission direction of each speaker of the first reproduction unit are determined in advance. The first angle. Also, a line connecting the center of the two speakers of the first reproduction unit and the center of the two speakers of the second reproduction unit and a direction perpendicular to the sound emission direction of each speaker of the second reproduction unit are determined in advance. The second angle.

  According to the sound reproducing device of the present invention, it is possible to localize two sound images at different positions even on a straight line connecting the centers of two speakers of two reproducing units, and to widen a listening area. Therefore, it is possible to reproduce the sound with the ease of listening by localizing the two sounds at different positions in a very wide range.

  First, the invention described in the patent document (Japanese Patent Application No. 2006-276424) filed by the applicant will be described. FIG. 4 is a diagram showing a configuration example of the sound reproducing device described in this application. This sound reproducing apparatus is used by being placed on an oval conference table 10, for example. This sound reproducing apparatus has one input channel signal Ch. One reproduction unit 20 in which an even number of speakers for reproducing 1 are arranged with the sound emission side facing outward, and the other reproduction unit 30 that is arranged apart from one reproduction unit and reproduces the other input channel signal With. The two sets of the reproduction units 20 and 30 have the same configuration, and are each composed of two speakers 20a and 20b and two speakers 30a and 30b. The speakers 20a and 20b, 30a and 30b of the two sets of reproduction units 20 and 30 are arranged symmetrically with respect to the straight line 40 connecting the centers of the respective sets, and the reproduction units 20 and 30 are at the midpoint of the straight line 40. They are arranged at symmetrical positions.

  Furthermore, a phase inverter 50 that inverts the phase of an input channel signal input to a part of speakers constituting one of the two reproduction units 20 and 30 is provided. In this example, the input channel signal Ch. 1 is phase-inverted by the phase inverter 50. Hereinafter, a speaker to which a phase-inverted signal is input is indicated by hatching in the drawings. The phase inverter 50 does not need to be arranged on the conference table 10. Thus, for example, three listeners A, B, and C and listeners E, F, and G are arranged on both sides of the straight line 40 around the conference table 10 on which the sound reproducing device is arranged on the desk. One listener D and one H are located at both ends in the extending direction.

  In this example, the input channel signal Ch. 1 and Ch. 2, the input channel signal Ch. Reproduced from the speakers 30a and 30b of the reproduction unit 30 is input. The sound of No. 2 is heard from any listener A to H with the sound image localized at the position of the reproduction unit 30. The input channel signal Ch. The sound 1 is heard from listeners A, B, and C and listeners E, F, and G located on both sides of the straight line 40 with a sound image localized at the position of the reproduction unit 20. On the other hand, for the listeners D and H located on the extension line of the straight line 40, the input channel signal Ch. The sound of No. 2 is received with the sound image being localized in the direction of either the left or right ear of the listeners D and H.

  That is, the input channel signal Ch. That is reproduced from the reproduction unit 20 is transmitted to the listeners D and H located in the extending direction of the straight line 40, which cannot obtain a good sound image localization by the conventional technique. 1 can be localized in one direction of the left or right ear of the listeners D and H, and the input channel signal Ch. The sound image of the second sound can be localized at the position of the reproduction unit 30. Further, from the listeners positioned on both sides of the straight line 40 connecting the playback units 20 and 30, the positions of the playback units 20 and 30 are separated from each other by a wide angle of view like the conventional sound playback device. Signal Ch. 1 is input to the position of the playback unit 20 and the input channel signal Ch. Sound 2 is heard at the position of the playback unit 30 with the sound image localized. In this example, it is possible to localize the sound images of the two sound sources to different positions for listeners located all around the sound reproduction device in this way, and easily distinguish the signals from these two sound sources. it can.

  FIG. 5 shows a configuration example of the sound reproducing device according to the first embodiment. The sound reproducing device 100 is also used, for example, arranged on an oval conference table 10 and reproduces two input channel signals (a signal of the first input channel Ch.1 and a signal of the second input channel Ch.2). To do. There are listeners A to H around the conference table 10. An object of the present invention is to localize sound images for the two sound sources at different positions, particularly at the positions of the listeners D and H. Also, the listener D and the listener H correspond to symmetrical positions with respect to the sound reproducing device 100. Therefore, in the following description, the localization of the sound image at the position of the listener D will be considered.

  The sound reproduction device 100 includes a reproduction unit 120 and a reproduction unit 130. The playback unit 120 is a Ch. Two speakers 20a and 20b, which are arranged so that the sound output direction is opposite, and a phase inverter 150 that reverses the phases of the input signals to the two speakers 20a and 20b. A level converter 160 is provided that gives a level difference between the input signals to the two speakers 20a and 20b. The playback unit 130 is disposed at a different position from the playback unit 120, and Ch. Two speakers 30a and 30b arranged so that the sound output direction is opposite, and a phase inverter 170 that reverses the phases of the input signals to the two speakers 30a and 30b. A level converter 180 is provided that gives a level difference to the input signals to the two speakers 30a and 30b. Then, the level converter 160 gives a predetermined level difference to the input signals to the speakers 20a and 20b. Moreover, the level converter 180 gives a predetermined level difference to the input signals to the speakers 30a and 30b.

  FIG. 6 shows reproduction directivity characteristics when the levels of the input signals to the speakers 20a and 20b are the same. There is a region where the reproduced sound pressure is extremely small in the directions of 0 degrees and 180 degrees. For a listener in this direction, the sound image tends to shift in a direction different from the direction of the speakers 20a and 20b. However, it is difficult to predict where it will deviate. When the phases of the signals of the two channels are reversed as shown in FIG. 5, a straight line 40 (0 connecting the centers of the two speakers 20a and 20b of the reproduction unit 120 and the centers of the two speakers 30a and 30b of the reproduction unit 130 is shown. The listeners above (degrees and 180 degrees) tend to feel a sound image in both channels other than the position of the speaker. At this time, if the localization is shifted in the same direction in both channels, the plurality of sound images are localized at the same position, and the plurality of sound images cannot be localized at different positions.

  FIG. 7 shows the reproduction directivity characteristics when a level difference is given to the input signals to the speakers 20a and 20b. The area where the sound pressure is small in the directions of 0 degrees and 180 degrees is the same as when the level is the same, but if the level difference is given, the sound pressure in the directions of 90 degrees and 270 degrees is greatly different. The listener from the right position can easily feel the sound image in the direction where the sound pressure is higher.

  In the case of the configuration of FIG. 1 makes the level of the input signal to the speaker 20a higher than the level of the input signal to the speaker 20b. The second signal makes the level of the input signal to the speaker 30b higher than the level of the input signal to the speaker 30a. If the level difference is set in this way, on the straight line 40 (direction of 0 degree and 180 degrees) connecting the center of the two speakers 20a and 20b of the reproduction unit 120 and the center of the two speakers 30a and 30b of the reproduction unit 130. The direction in which the sound image shifts differs for each channel. Accordingly, the sounds of the two channels can be distinguished. Note that what level difference is effective may be appropriately designed based on the sound reflection state of the room.

  As described above, according to the sound reproducing apparatus of the first embodiment, two sound images can be localized at different positions even on a straight line connecting the centers of two speakers of two reproducing units, and the listening area can be expanded. be able to. Therefore, it is possible to reproduce the sound with the ease of listening by localizing the two sounds at different positions in a very wide range.

FIG. 8 shows a configuration example of the sound reproducing device according to the second embodiment. The sound reproducing device 200 reproduces two input channel signals (a first input channel signal and a second input channel signal). The sound reproducing device 200 is also used, for example, arranged on an oval conference table 10 and reproduces two input channel signals (a signal of the first input channel Ch.1 and a signal of the second input channel Ch.2). To do. The sound reproduction device 200 includes a reproduction unit 220 and a reproduction unit 230. The playback unit 220 is a Ch. One signal is used as an input signal, and the two speakers 220a and 220b arranged so that the sound emission directions are opposite to each other, and the phase inverter 250 that reverses the phases of the input signals to the two one speakers 220a and 220b. Have The playback unit 230 is disposed at a different position from the playback unit 220, and Ch. Two speakers 230a and 230b, which are arranged so that the sound output direction is opposite to each other, and a phase inverter 270 that reverses the phases of the input signals to the two speakers 230a and 230b. Have. The straight line 40 connecting the center of the two speakers 220a and 220b of the reproduction unit 220 and the center of the two speakers 230a and 230b of the reproduction unit 230 is perpendicular to the sound emission direction of the speakers 220a and 220b of the reproduction unit 220. The direction is a predetermined angle θ ₂₂₀ . Further, the straight line 40 and the direction perpendicular to the sound emitting direction of the speakers 230a and 230b of the reproduction unit 230 are a predetermined angle θ ₂₃₀ .

FIG. 9 shows the directivity characteristics of the reproduction units 220 and 230 of the sound reproduction device 200. Since the pair of speakers is rotated by θ ₂₂₀ and θ ₂₃₀ , respectively, the region where the sound pressure of both channels is low is shifted from the direction of 0 degree or 180 degrees (on the extended line of the straight line 40). In particular, as shown in FIGS. 8 and 9, if the pair of speakers is rotated in the opposite direction with respect to the straight line 40, the direction in which the sound image is shifted is different because the direction in which the sound pressure decreases is different. Different for each channel. Accordingly, the sounds of the two channels can be distinguished. In addition, the range in which listening can be performed by shifting the localization of the two channels can be widened.

θ ₂₂₀ and θ ₂₃₀ differ depending on the positional relationship between the set of speakers and the listener. Two sets of the distance of the speaker between _{L 1,} listener and speakers 220a, the distance between 220b and _{L 2.} In this case, the place where the sound pressure is low is shifted from the listener D by (L ₁ + L ₂ ) sin θ ₂₂₀ and L ₂ sin θ ₂₃₀ . Since the position where the sound pressure is reduced is desirably equal to or greater than the listener's head width (ear interval), a range of 0.2 m to 0.3 m is desirable. Considering the size of the playback device, L ₂ is generally 0.5 m to 3 m, and L ₁ is generally 0.5 m to ₁ m. Therefore, θ ₂₂₀ = 38 degrees for 0.5 m × sin θ ₂₂₀ = 0.3 m, and θ ₂₃₀ = 3 degrees for 4 m × sin θ ₂₃₀ = 0.2 m. Since the positional relationship is reversed when the listener is H, both θ ₂₂₀ and θ ₂₃₀ are preferably set between 3 and 38 degrees. That is, θ ₂₂₀ and θ ₂₃₀ may be in the range of 3 degrees to 38 degrees and may be shifted in opposite directions with respect to the straight line 40.

  Due to such a structure, according to the sound reproducing device of the present invention, when a speaker that reproduces signals of two different sound sources is positioned in front of the listener, the direction of the sound image when the position is shifted to other than the front is controlled. And the expansion of the area is facilitated, and the two sounds can be easily distinguished at all positions surrounding the sound reproducing device.

The figure which shows the most fundamental structure of the sound reproduction apparatus which carries out loud sound reproduction of the signal of 2 channels with a some speaker. The figure which shows the structure of the sound reproduction apparatus shown by the nonpatent literature 1. FIG. The figure which shows the structure of the sound reproduction apparatus shown by the nonpatent literature 2. FIG. The figure which shows the structure of the sound reproduction apparatus shown by Japanese Patent Application No. 2006-276424. 1 is a diagram illustrating a configuration example of a sound reproduction device according to Embodiment 1. FIG. The figure which shows the reproduction | regeneration directivity characteristic when the level of the input signal to the speakers 20a and 20b is the same. The figure which shows the reproduction | regeneration directivity characteristic at the time of giving a level difference to the input signal to the speakers 20a and 20b. FIG. 6 is a diagram illustrating a configuration example of a sound reproduction device according to a second embodiment. The figure which shows the directional characteristic of each reproduction | regeneration unit 220,230 of the sound reproduction apparatus 200. FIG.

Explanation of symbols

100, 200 Sound reproduction device 120, 130, 220, 230 Reproduction unit 150, 170, 250, 270 Phase inverter 160, 180 Level converter 20a, 20b, 30a, 30b, 220a, 220b, 230a, 230b Speaker

Claims (8)

A sound reproducing device for reproducing two signals, a first input channel signal and a second input channel signal,
The first input channel signal is used as an input signal, and the first phase in which the phases of the input signals to the two first speakers and the two first speakers arranged in opposite directions are opposite to each other A first reproduction unit having an inverter and a first level converter for giving a level difference to the input signals to the two first speakers;
Two second speakers arranged at positions different from the first reproduction unit, with the second input channel signal as an input signal, and arranged so that sound emission directions are opposite to each other, and to the two second speakers A sound reproduction device comprising: a second phase inverter that reverses the phases of the input signals of each other, and a second reproduction unit that includes a second level converter that provides a level difference between the input signals to the two second speakers. A sound reproducing device for reproducing two signals, a first input channel signal and a second input channel signal,
The first input channel signal is used as an input signal, and the first phase in which the phases of the input signals to the two first speakers and the two first speakers arranged in opposite directions are opposite to each other A first reproduction unit having an inverter;
Two second speakers arranged at positions different from the first reproduction unit, with the second input channel signal as an input signal, and arranged so that sound emission directions are opposite to each other, and to the two second speakers A second reproduction unit having a second phase inverter for reversing the phases of the input signals of
A line connecting the centers of the two speakers of the first reproduction unit and the centers of the two speakers of the second reproduction unit (hereinafter referred to as “center line”) and the sound emission direction of each speaker of the first reproduction unit And the direction perpendicular to the first angle is a predetermined first angle,
The center line and a direction perpendicular to the sound emission direction of each speaker of the second reproduction unit are a predetermined second angle. The sound reproducing device according to claim 2,
The direction perpendicular to the sound emission direction of each speaker of the first reproduction unit and the direction perpendicular to the sound emission direction of each speaker of the second reproduction unit are shifted in opposite directions with respect to the center line. A sound reproducing apparatus characterized by the above. The sound reproducing device according to claim 3,
The sound reproducing apparatus, wherein the first angle and the second angle are in a range of 3 degrees to 38 degrees. An acoustic reproduction method for controlling an acoustic reproduction apparatus that reproduces two of a first input channel signal and a second input channel signal,
The sound reproducing device is
The first input channel signal is used as an input signal, and the first phase in which the phases of the input signals to the two first speakers and the two first speakers arranged in opposite directions are opposite to each other A first reproduction unit having an inverter and a first level converter for giving a level difference to the input signals to the two first speakers;
Two second speakers arranged at positions different from the first reproduction unit, with the second input channel signal as an input signal, and arranged so that sound emission directions are opposite to each other, and to the two second speakers A second phase inverter that reverses the phases of the input signals to each other, and a second reproduction unit having a second level converter that gives a level difference to the input signals to the two second speakers,
The sound reproduction method according to claim 1, wherein the first level converter and the second level converter give a predetermined level difference. An acoustic reproduction method for controlling an acoustic reproduction apparatus that reproduces two of a first input channel signal and a second input channel signal,
The sound reproducing device is
The first input channel signal is used as an input signal, and the first phase in which the phases of the input signals to the two first speakers and the two first speakers arranged in opposite directions are opposite to each other A first reproduction unit having an inverter;
Two second speakers arranged at positions different from the first reproduction unit, with the second input channel signal as an input signal, and arranged so that sound emission directions are opposite to each other, and to the two second speakers A second reproduction unit having a second phase inverter for reversing the phases of the input signals of
A line connecting the centers of the two speakers of the first reproduction unit and the centers of the two speakers of the second reproduction unit (hereinafter referred to as “center line”) and the sound emission direction of each speaker of the first reproduction unit And the perpendicular direction to the predetermined first angle,
The sound reproduction method, wherein the center line and a direction perpendicular to the sound output direction of each speaker of the second reproduction unit are adjusted to a predetermined second angle. It is the sound reproduction method of Claim 6, Comprising:
The direction perpendicular to the sound emission direction of each speaker of the first reproduction unit and the direction perpendicular to the sound emission direction of each speaker of the second reproduction unit are shifted in opposite directions with respect to the center line. An acoustic reproduction method characterized by the above. The sound reproduction method according to claim 7,
The sound reproduction method, wherein the first angle and the second angle are in the range of 3 degrees to 38 degrees.

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