JP2011193195A - Sound-field control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To use a 5.1-channel speaker configuration in order to achieve sound-field reproduction that allows a listener to feel a surround sound field that is natural and seamless in all directions while making the listener unaware that the sound is reproduced from speakers regardless of the position relation between the speakers and the listener and without damaging the surround feeling of content. <P>SOLUTION: For example, when a sound image is localized at a virtual speaker 411(VFL) position sandwiched between a speaker 401(FL) and a speaker 403(SL) by supplying FL signals to the speakers after equalizing the signals by a signal processing part 200, a virtual sound-source direction including indirect sound is measured so as to control the signal distribution ratio to the two speakers on the basis of the measurement result, thereby localizing the sound image at the desired virtual speaker position. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a basic form of a home theater system (home theater), a 5.1 channel speaker system including a set of surround channel speakers, or a 7.1 channel speaker system including two sets of surround channel speakers. Nevertheless, the present invention relates to a sound reproducing device for reproducing a diffuse sound field with a rich sense of sound field.

  Recently, with the advent of media that provides high-definition and multi-channel audio, such as digital broadcasting and Blu-ray discs, it has become possible to enjoy high-quality and high-quality content easily at home. Furthermore, with the widespread use of thin large-screen TVs, home theaters for enjoying movies at home are in the spotlight. In particular, there is a demand for an audio playback system that can provide high-quality sound that is comparable to a large screen. In particular, the Blu-ray disc has a format for recording 13.1 channel audio signals (7.1 channel is the maximum in the current contents), and the expectation expands to the sound field full of presence that the reproduced sound brings. On the other hand, as the number of channels increases, the sense of reality increases, but the number of speakers for reproducing it increases, and it is far from being easy in a home theater handled at home.

  In view of this, a multi-channel sound field reproduction apparatus having a multi-channel sound field reproduction system for reproducing 7.1-channel signals with 5.1-channel speakers has been proposed.

  FIG. 9 is a diagram showing an example of a conventional multi-channel sound field reproduction device (see Patent Document 1).

  Hereinafter, the operation of the conventional multi-channel sound field reproduction apparatus will be described with reference to FIG.

  FIG. 9 shows an example of a multi-channel sound field reproduction method for reproducing a 7.1-channel signal with a 5.1-channel speaker. An arithmetic unit F1a that generates a sum signal and a difference signal of the back surround signals BL and BR The FIR filter F1b that processes the sum signal, the FIR filter F1c that processes the difference signal, the arithmetic unit F1d that generates the sum signal and the difference signal of the signals processed by the FIR filters F1b and F1c, and the arithmetic unit F1d The adder a and the adder b add the sum signal and the difference signal processed in step 1 to the side surround signals SL and SR, respectively.

  For audio reproduction in the 5.1 channel system, an ITU-R BS. The speaker arrangement of the 775-1 recommendation is recommended, and the back surround channel added by 7.1 channel is installed around 150 degrees further rearward than SL and SR. In this conventional example, the back surround channel audio signals BL and BR are signal-processed and added to the surround channel signals SL and SR, thereby providing a 5.1 channel speaker configuration without a back surround channel speaker. 7.1 The effect of the channel is produced.

  First, 5.1-channel surround speakers SL and SR are arranged in a 90-degree direction (right and left lateral direction of the viewer) rather than in a 120-degree direction (diagonal left and right backward of the viewer).

As shown in FIG. 10, the back surround signal is processed by generating a sum / difference component of a pair of back surround signals BL and BR, then the sum signal is processed by the FIR filter F1b, and the difference signal is processed by the FIR filter F1c. When these sum / difference signals are generated and output to the SL and SR speakers, the transfer characteristics P and N of the obtained FIR filters F1b and F1c are P = (F + K) / (S + A).
N = (F−K) / (S−A)
Indicated by Here, S is a transfer characteristic from the real speakers SL and SR to the ear on the same side of the viewer, A is a transfer characteristic from the real speakers SL and SR to the ear on the opposite side of the viewer, and F is to localize the sound image. The transfer characteristics from the virtual speakers BL and BR assumed to the position to the ears on the same side of the viewer, K is the transfer characteristics from the virtual speakers BL and BR to the ears on the opposite side of the viewer, and the head-related transfer function of the viewer Is used.

  In this way, the pair of back surround signals BL and BR are subjected to sound image localization processing, added to the SL and SR channel audio signals by the adder a and adder b, respectively, and left and right side surround speakers SL as output signals of the SL and SR channels. , SR to be reproduced. In this way, the back surround signal is subjected to sound image localization processing, added to the side surround speaker, and played back, so that 7.1 channel sound image localization and realism can be easily created in a general home. it can.

JP 2005-341208 A

  However, the conventional technology has a configuration in which the surround speaker is installed in the lateral direction of the viewer so that the head-related transfer characteristics for surround back can be faithfully reproduced. Has a problem that is greatly affected.

  In addition, since the speaker is installed in the lateral direction, the sound field formed by the original surround channel cannot be faithfully reproduced.

  Furthermore, even if the 7.1-channel speaker can be completely reproduced with this conventional technology, the sound field can be reproduced in such a way that a natural surround without a joint is felt in all directions beyond the 7.1-channel. Had problems that could not be done.

  Also, due to the influence of the room where the speakers are actually installed, there is a problem that the sound field formed by the original surround channel cannot be faithfully reproduced.

  The present invention solves the problems of the prior art, and is reproduced from the speaker without being affected by the positional relationship between the speaker and the viewer, without impairing the surround feeling of the content. It is an object of the present invention to construct a sound reproduction device that realizes sound field reproduction that makes it feel natural surround without joints in all directions with a 5.1-channel speaker configuration.

  Furthermore, an object of the present invention is to optimally reproduce the sound field formed by the original surround channel according to the situation of the room where the speakers are actually installed.

  In order to solve the above problems, a sound reproduction device of the present invention processes a first input signal and a second input signal and outputs them to a first speaker and a second speaker; The virtual sound source direction angle of the synthesized sound obtained by synthesizing the direct sound and the indirect sound coming from the first speaker and the second speaker to the viewing point is measured, and the signal is based on the measured virtual sound source direction angle. A measurement unit that controls the processing unit, wherein the signal processing unit equalizes the first input signal with a first equalizer characteristic, delays the first input signal with a first delay characteristic, and adjusts the level with a first coefficient. A first signal processor; a second signal processor that equalizes the first input signal with a second equalizer characteristic, delays the first input signal with a second delay characteristic, and adjusts the level with a second coefficient; and Input signal with a third factor. A first adder that adds the signal adjusted to the output signal of the first signal processor and outputs the result to the first speaker, and a signal obtained by adjusting the level of the second input signal by a fourth coefficient. And a second adder that adds the output signal of the second signal processor and outputs the second signal to the second speaker, and the measurement unit performs the measurement with respect to the signal processing unit during measurement. The virtual speaker is controlled so that the third coefficient and the fourth coefficient are zero, and the virtual sound source direction angle is assumed to be a predetermined position between the first speaker and the second speaker. The distribution ratio between the first coefficient and the second coefficient of the signal processing unit is controlled so that the angle becomes the angle.

  In addition, the measurement unit uses at least one unidirectional microphone to measure the sound pressure characteristic of the synthesized sound that arrives at the viewing point in predetermined angle increments, and based on the measurement result, the virtual part The characteristic sound source direction angle is calculated.

  Further, the measurement unit is characterized in that the sound pressure characteristic measured by the microphone is equalized with the frequency characteristic of the head transmission characteristic in increments of the predetermined angle as the measurement result. .

  The first equalizer characteristic is a characteristic obtained by dividing a head-related transfer function from the virtual speaker to the viewing point by a head-related transfer function from the first speaker to the viewing point. The equalizer characteristic is a characteristic obtained by dividing the head-related transfer function from the virtual speaker to the viewing point by the head-related transfer function from the second speaker to the viewing point.

  The signal processing unit adjusts the level of the first signal by a fifth coefficient and supplies the first signal to the first signal processor and the second signal processor, and the measurement unit performs the signal processing. It is characterized by having the adjustment means in which the viewer for changing the said 5th coefficient of a part can be adjusted.

  The first speaker and the second speaker are a front L channel speaker and a surround L channel speaker, a front R channel speaker and a surround R channel speaker, or a surround L channel speaker in a 5.1 channel speaker configuration. It is a surround R channel speaker.

  The sound field control device according to the present invention has a 5.1 channel speaker configuration actually installed by the above configuration, has a wide service area, and is further reproduced from the speaker without impairing the surround feeling of the content. Sound field reproduction that makes you feel the natural surround without being connected in all directions without making you conscious of it, and easy reproduction of the sound field as intended (for example, emphasizing the sound pressure and spread of a specific channel) It can be accurately realized with a simple configuration.

1 is a block diagram of a sound reproduction device according to Embodiment 1 of the present invention. Explanatory drawing of speaker arrangement in Embodiment 1 of the present invention The block diagram of the signal processing part in Embodiment 1 of this invention Characteristic chart showing head-related transfer characteristics The figure which shows the equalizer characteristic example in Embodiment 1 of this invention The figure which shows the state of the signal processing part at the time of the measurement in Embodiment 1 of this invention The figure which shows the example of a measurement result in Embodiment 1 of this invention Image diagram of sound pressure characteristics of adjustment example in Embodiment 4 of the present invention Block diagram of a conventional audio playback device The figure which shows operation | movement of the conventional audio reproduction apparatus. ITU-R BS. Speaker layout diagram recommended by 775-1

(Embodiment 1)
The operation and components of the sound reproducing device according to Embodiment 1 of the present invention will be described in detail below.

  FIG. 1 is a block diagram showing a configuration of a sound reproducing device according to Embodiment 1 of the present invention. The sound reproducing apparatus shown in FIG. 1 reproduces a 7.1 channel signal in a sound field corresponding to 11.1 channel using a 5.1 channel speaker system.

  In FIG. 1, reference numeral 100 denotes a 7.1-channel multi-channel audio signal, that is, a front L channel signal (FL signal), a front R channel signal (FR signal), a surround L channel signal (SL signal), and a surround R channel signal. (SR signal), surround back L channel signal (BL signal), surround back R channel signal (BR signal), center channel signal (C signal) and bass effect channel signal (LFE signal). As a specific example, it refers to a Blu-ray disc having 7.1 channel audio signal content and its playback player. 200 is a signal for performing signal processing for reproducing the sound field corresponding to the sound field reproduced by the 11.1 channel speaker system on the 5.1 channel speaker system on the output signal of the signal generating unit 100. The processing unit 300 is a power amplification unit that amplifies the output signal of the signal processing unit 200, 401 is a front L channel speaker (FL speaker), 402 is a front R channel speaker (FR speaker), and 403 is surround. L channel speaker (SL speaker), 404 surround R channel speaker (SR speaker), 405 is a center channel speaker (C speaker), 406 is a bass effect channel speaker (LFE speaker), These speakers 401 to 406 are 5.1 channel speakers. Make up a stem. Reference numeral 500 denotes a microphone arranged at the viewing point, and 600 denotes a sound pressure characteristic of the reproduced sound that arrives at the viewing point at a predetermined step angle based on the output signal of the microphone 500, and the signal processing unit 200 based on the result of processing the sound pressure characteristics. It is a measurement part which controls.

  FIG. 2 shows the arrangement of the virtual speakers 411 to 416 to be reproduced and the speakers 401 to 406 that actually exist in the sound reproduction device according to Embodiment 1 of the present invention.

  FIG. 3 shows a specific configuration of the signal processing unit 200. Reference numeral 210 denotes a switch group including switches 211 to 217 that selectively switch an input signal based on the output of the measurement unit 600. Reference numeral 220 denotes a level adjuster group including level adjusters 221 to 231 that adjust the levels of the output signals of the switches 211 to 217 based on the output of the measurement unit 600. Reference numerals 241 to 252 are delay equalizers in which an equalizer and a delay are cascade-connected. The delay equalizers 241 and 243 receive the output signal of the level adjuster 222, and the delay equalizers 242 and 244 input the output signal of the level adjuster 223. The delay equalizers 245 and 247 receive the output signal of the level adjuster 225, the delay equalizers 246 and 248 input the output signal of the level adjuster 227, and the delay equalizers 249 and 251 receive the output signal of the level adjuster 229. The delay equalizers 250 and 252 input the output signal of the level adjuster 230. Reference numeral 260 denotes a level adjuster group including level adjusters 261 to 272 that adjust the levels of the output signals of the delay equalizers 241 to 252 based on the output of the measurement unit 600. 281 is an adder for adding the output signals of the level adjusters 221, 261, 262, 282 is an adder for adding the output signals of the level adjusters 263 to 266, and 283 is to add the output signals of the level adjusters 267 to 270. An adder 284 is an adder that adds the output signals of the level adjusters 231, 271, 272.

  The operation of the sound field reproducing apparatus according to Embodiment 1 of the present invention configured as described above will be described in detail.

  The 7.1-channel audio signal output from the signal generation unit 100 is input to the signal processing unit 200. In the signal processing unit 200, a sound field formed when a 7.1 channel content is reproduced with a 11.1 channel speaker system configuration including a real speaker and a virtual speaker shown in FIG. Signal processing is performed for reproduction by the channel speaker system. Here, the arrangement of the 5.1-channel speaker system is the same as that of the ITU (International Telecommunication Union) -R BS10 TG10 / 1 recommendation 775-1 shown in FIG. The center speaker is arranged on a concentric circle of 0 degrees, the front speaker is arranged on the left and right 30 degrees, and the surround speaker is arranged on the right and left 120 degrees).

  On the other hand, as a virtual speaker to be reproduced other than a real speaker, a surround back channel virtual speaker 415 (VBL speaker) that reproduces a surround back L channel signal (BL signal) included in the reproduction content, and a surround back R channel signal (BR signal). A virtual speaker 416 (VBR speaker) for surround back channel is reproduced.

  Also, in the 5.1 channel or 7.1 channel speaker arrangement, the speaker spacing between the front channel and the surround channel is increased by 90 degrees to the left and right, so that there is a lack of a seamless sound field between the front channel and the surround channel. In order to improve this, a virtual speaker 411 (VFL speaker) for localizing the FL signal at a position of 60 degrees left between the speaker 401 (FL speaker) and the speaker 403 (SL speaker), and 90 degrees left A virtual speaker 413 (VSL speaker) for localizing the SL signal is arranged at the position, and similarly, the FR signal is localized at a position of 60 degrees to the right between the speaker 402 (FR speaker) and the speaker 404 (SR speaker). A virtual speaker 412 (VFR speaker) for positioning the sound signal and a virtual speaker 414 (VSR speaker) for localizing the SR signal at a position of 90 degrees to the right.

  Therefore, in the first embodiment of the present invention, C (0 degree), FL (30 degrees left), VFL (60 degrees left), FR (30 degrees right), VFR (60 degrees right), SL (120 degrees left) ), SR (120 degrees right), VBL (150 degrees left), VBR (150 degrees right), and LFE sound field reproduced by 11.1 channel speakers reproduced by 5.1 channel speaker system To do.

  Here, a general method for reproducing a reproduction sound (particularly sound source localization) from a virtual speaker corresponding to a channel that does not exist in an actual real speaker will be described.

  This is realized by using two real speakers A and B that exist in a manner sandwiching the installation angle of the virtual speaker V to be reproduced. When the same sound source is reproduced from two speakers, a synthesized sound of reproduced sounds from the two speakers can be generated so that the sound source is localized at a position where the vector synthesis is performed by weighting the level ratio. That is, if the angle formed by the real speaker A and the virtual speaker V viewed from the viewing position is a, and the angle formed by the real speaker B and the virtual speaker V is b, the levels PA and PB of the speakers A and B are respectively

It becomes. That is, the ratio of PA to PB is

It becomes.

  When this speaker A is fitted to the speaker 401 (FL speaker), the speaker B is fitted to the speaker 403 (SL speaker), and the speaker V is fitted to the virtual speaker 411 (VFL speaker), a = 30 degrees and b = 60 degrees. From (Equation 3), PA: PB = 0.86: 0.5. This is applied to the level adjusters 261 and 263 of FIG. 3, and the coefficient K61 of the level adjuster 261 is set to 0.86, and the coefficient K63 of the level adjuster 263 is set to 0.5.

  Further, when the speaker V is fitted to the virtual speaker 413 (VSL speaker), a = 60 degrees and b = 30 degrees, so PA: PB = 0.5: 0.86 from (Equation 3). This is applied to the level adjusters 262 and 264 shown in FIG. 3 so that the coefficient K62 of the level adjuster 262 is set to 0.5 and the coefficient K64 of the level adjuster 264 is set to 0.86.

  Similarly, the coefficients K69 to 72 of the level adjusters 269 to 272 on the R side may be set to 0.86, 0.5, 0.5, and 0.86.

  When the speaker A is fitted to the speaker 403 (SL speaker), the speaker B is fitted to the speaker 404 (SR speaker), and the speaker V is fitted to the virtual speaker 415 (VBL speaker), a = 30 degrees and b = 90 degrees. Therefore, from (Equation 3), PA: PB = 1: 0.5. In order to prevent the synthesized sound pressure from changing while maintaining the distribution ratio, PA: PB = 0.89: 0.45, which is applied to the level adjusters 265 and 267 of FIG. 3, and the coefficient K65 of the level adjuster 265 is set to 0.89, and the coefficient K67 of the level adjuster 267 is set to 0.45. You only have to set it.

  Similarly, the coefficients K68 and 66 of the level adjusters 268 and 266 on the R side may be set to 0.89 and 0.45, respectively.

  As described above, basically, the coefficients K61 to 72 of the level adjusters 261 to 272 of the level adjuster group 260 may be set to the above values. However, as will be described later, Since the sound source direction angle of the virtual speaker changes due to the influence of the reflected sound from the ceiling, furniture, etc., in order to correct it and localize the virtual speaker at the desired position, the distribution ratio of each coefficient is as follows. It can be adjusted.

  On the other hand, we humans feel the sound with our ears, but the sound transmitted to the ear is not only the direct sound from the sound source but also the one that passes through the human body, especially the head. Therefore, the sound transmission characteristic from the sound source to the ear is affected by the human body, particularly the head and pinna, and has a frequency characteristic, which varies depending on the presentation position of the sound source. This is called head-related transfer characteristics. Humans can identify the position of the sound source because they know the head-related transfer characteristics and their angular dependence. An example of the head transfer characteristic is shown in FIG.

  FIG. 4 shows the position of the speaker from the speaker to the viewer's left ear when placed at 30 °, 60 °, 90 °, 120 °, and 150 ° counterclockwise when viewed from the front of the viewer. The frequency characteristic of the head-related transfer function is shown.

  In Embodiment 1 of the present invention, by applying this human sound localization mechanism, the head-related transfer characteristic from the virtual speaker is determined based on the relative relationship between the installation angle of the actual speaker and the virtual speaker to be realized. As given to the viewer, by controlling the frequency characteristics from the real speaker, it is possible to feel as if the sound comes from the virtual speaker to be realized (the sound is localized).

  In general, an input signal is equalized with an equalizer characteristic A and supplied to the speaker A, and equalized with an equalizer characteristic B and supplied to the speaker B, so that the virtual speaker V is positioned between the speaker A and the speaker B. Is realized by dividing the head transmission characteristic from the virtual speaker V to the viewer by the head transmission characteristic from the real speaker A to the viewer, and the equalizer characteristic B is obtained from the virtual speaker V. What is necessary is just to make it the characteristic which remove | divided the head transmission characteristic to a viewer by the head transmission characteristic from the real speaker B to a viewer.

  This concept will be described with reference to FIG. 3 showing a specific configuration of the signal processing unit 200 for reproducing the virtual speaker shown in FIG. Here, since the same processing is performed on the left and right, only the L channel will be described. Also, the LFE channel is not shown because it does not process anything in the signal processing unit 200.

  As shown in FIG. 2, since the virtual speaker 411 (VFL speaker) and the virtual speaker 413 (VSL speaker) are sandwiched between the speaker 401 (FL speaker) and the speaker 403 (SL speaker), they are reproduced by these two speakers.

  The FL signal for localization to the virtual speaker 411 (VFL speaker) is output to the speaker 401 (FL speaker) via the switch 211, the level adjuster 222, the delay equalizer 241, the level adjuster 261, and the adder 281. , The switch 211, the level adjuster 222, the delay equalizer 243, the level adjuster 263, and the adder 282, and output to the speaker 403 (SL speaker).

  The equalizer characteristic EQ41 of the delay equalizer 241 realizes (60-degree head transmission characteristic) / (30-degree head transmission characteristic), and the equalizer characteristic EQ43 of the delay equalizer 243 is (60-degree head transmission characteristic). (Transmission characteristics) / (120-degree head transmission characteristics) is realized. FIG. 5 shows an example of frequency characteristics of the equalizer characteristics EQ41 and EQ43 realized in this way.

  Similarly, an SL signal for localization to the virtual speaker 413 (VSL speaker) is output to the speaker 401 (FL speaker) via the switch 212, the level adjuster 223, the delay equalizer 242, the level adjuster 262, and the adder 281. At the same time, the signal is output to the speaker 403 (SL speaker) via the switch 212, the level adjuster 223, the delay equalizer 244, the level adjuster 264, and the adder 282.

  The equalizer characteristic EQ42 of the delay equalizer 242 realizes (head transmission characteristic in the 90 degree direction) / (head transmission characteristic in the 30 degree direction), and the equalizer characteristic EQ44 of the delay equalizer 244 is (head part in the 90 degree direction). (Transmission characteristics) / (120-degree head transmission characteristics) is realized.

  Further, since the virtual speaker 415 (VBL speaker) is sandwiched between the speaker 403 (SL speaker) and the speaker 404 (SR speaker), it is reproduced by these two speakers.

  The BL signal for localization to the virtual speaker 415 (VBL speaker) is output to the speaker 403 (SL speaker) via the switch 213, the level adjuster 225, the delay equalizer 245, the level adjuster 265, and the adder 282. , The switch 213, the level adjuster 225, the delay equalizer 247, the level adjuster 267, and the adder 283, and output to the speaker 404 (SR speaker).

  The equalizer characteristic EQ45 of the delay equalizer 245 realizes (head transmission characteristic in the direction of 150 degrees left) / (head transmission characteristic in the direction of 120 degrees left), and the equalizer characteristic EQ47 of the delay equalizer 247 is (the direction of 150 degrees left) (Head transfer characteristic of 120 degrees to the right).

  Similarly, the equalizer characteristic EQ46 of the delay equalizer 246 realizes (head propagation characteristic in the direction of 150 degrees to the right) / (head transmission characteristic in the direction of 120 degrees to the left), and the equalizer characteristic EQ48 of the delay equalizer 248 is (left (Head transmission characteristic in the direction of 150 degrees) / (head transmission characteristic in the direction of 120 degrees to the right) is realized.

  The head-related transfer characteristic may be calculated using the head-related transfer characteristic itself, or may be only the amplitude characteristic calculated using the head-related transfer characteristic itself, or the head-related transfer characteristic itself may be used. It may be a simple realization of only the amplitude characteristic calculated in the above. As a simple realization method, a graphic equalizer such as a 1/3 oct bandwidth may be used, or about five from a large or small amplitude level are extracted in a band of 1 kHz or more of the calculated amplitude characteristic, and the center frequency is extracted. Alternatively, a parametric equalizer whose characteristics can be determined by the Q value and the amplitude level may be realized. When the equalizer is realized by a 5-band parametric equalizer, as shown in FIG. 5, five characteristic peak dip points (EQ41-1 to EQ43-1, EQ43-) calculated based on the head-related transfer characteristics are used. The characteristics may be approximated by including 1 to 5).

  Here, the coefficients K21 to 31 of the level adjusters 221 to 231 of the level adjuster group 220 are basically 1 in which the level does not change depending on input and output. It may be changed accordingly.

  Next, the effect of the delay connected to the equalizer will be described.

  The original signals for reproducing the VFL speaker and the VSL speaker are the FL signal and the SL signal as in the FL speaker and the SL speaker, respectively. For this reason, a sound source representing the state of the field can be heard so that the sound pressure is distributed over a wide range, so that it is very effective in enhancing the sense of spread of the sound field, the feeling of being wrapped in sound, and the like. However, sound sources intended to pinpoint sound localization tend to be unclear because the same sound source is played from multiple locations.

  On the other hand, when the same sound is sent from a plurality of sound sources called a precedence sound effect (Haas effect) to a human, a phenomenon that the sound image is localized in the direction of the sound that first reaches the ear (range shorter than about 25 to 35 msec) Effective). By utilizing this phenomenon, the sound corresponding to the VFL speaker and the VSL speaker is delayed by about 1 msec with respect to the sound from the FL speaker and the SL speaker. In addition, the sound speaker has a clear sound localization at the position of the SL speaker, and the connection with the sound from the VFL speaker and the SL speaker is not impaired for sounds such as environmental sounds that do not rise sharply.

  In the present invention, the first input signal, the second input signal, the first speaker, the second speaker, the first signal processor, the second signal processor, the first adder, and the second adder The adders correspond to the FL signal, SL signal, FL speaker, SL speaker, delay equalizer 241 and level adjuster 261, delay equalizer 243 and level adjuster 263, adder 281 and adder 282, respectively, in the present embodiment. ing.

  With the above configuration, a virtual speaker is generated and played between two real speakers, and surround that lacks a sense of connection with only the playback sound from the real speakers is achieved with a seamless and natural sound field space reproduction. is doing.

  In addition, in order to realize a desired sound field characteristic at the viewing point (for example, a seamless sound field feeling seamlessly connected to the playback sound of each channel), the arrangement of 11 real and virtual speakers excluding LFE is arranged. It needs to be appropriate.

  However, in reality, the sound source direction angle and playback level of each speaker change due to the influence of reflected sound from the walls, floors, ceilings, furniture, etc. of the room being viewed. The feeling is impaired. Therefore, in order to obtain a seamless sound field feeling without joints, each speaker is controlled so that the virtual speaker position that can actually be heard is adjusted to a desired position, and the level of each speaker that is actually heard is controlled. It is necessary to control to be uniform. The control method will be described below.

  First, using the unidirectional microphone 500 shown in FIG. 1, the sound pressure characteristic of the synthesized sound obtained by synthesizing the direct sound and the indirect sound arriving at the viewing point in predetermined angular increments (for example, in increments of 30 degrees) is measured. Based on the sound pressure characteristics, the measurement unit 600 calculates a virtual sound source direction angle of the synthesized sound, and a signal processing unit so that the calculated virtual sound source direction angle becomes a desired virtual speaker position. 200 level adjuster groups 260 are adjusted.

  A specific operation will be described.

  For example, when adjusting the position of the virtual speaker 411 (VFL speaker), the switch 211 of the switch group 210 is set to ON and the other switches are set to OFF under the control of the measurement unit 600. Then, the coefficient K21 of the level adjuster 221 of the level adjuster group 220 is set to 0, and the coefficient K22 of the level adjuster 222 is set to 1. Further, the coefficient K61 of the level adjuster 261 of the level adjuster group 260 is set to a default value of 0.86, and the coefficient K63 of the level adjuster 263 is set to a default value of 0.5. With this setting, the FL signal is reproduced by the speaker 401 (FL speaker) and the speaker 403 (SL speaker). The sound pressure characteristics of the synthesized sound including the direct sound and the indirect sound of the reproduced sound are measured with the microphone 500.

  The same idea applies when measuring other speakers. FIG. 6 shows a setting state of the switch group 210 and the level adjuster group 220 when measuring each speaker.

  When a microphone having a unidirectional characteristic is used for measurement as the microphone 500, the microphone is installed at the viewing point, the front of the viewing point (in the center channel direction) is set to zero degrees, and the microphone 500 is divided in 12 steps. To measure. Alternatively, instead of rotating and measuring one microphone in increments of 30 degrees, 12 microphones having the same characteristics are prepared and arranged in increments of 30 degrees and collectively measured. If six microphones having the same characteristics can be prepared, the measurement is performed by dividing the microphone into two parts by arranging in 30 degree increments. Further, a measurement method of measuring only one of the left and right as symmetry, or a combined configuration of the above-described microphone usage method is conceivable.

  The sound pressure characteristic obtained in this way indicates the sound pressure intensity in the direction of arrival in increments of 30 degrees at the viewing point of the reproduced sound from each speaker.

  As the measurement signal to be input, band-limited white noise, wobble tone, impulse signal, or the like can be used. Here, a signal that sweeps between 100 Hz and 750 Hz in a short time is used.

  A virtual sound source direction angle is calculated from the twelve sound pressure characteristics thus measured. An example of the measurement and calculation results is shown in FIG. This is an example of measuring real speakers (FL, FR, SL, SR, C speakers), and the longest straight line among the radial lines represents the virtual sound source direction angle of the synthesized sound and its sound pressure level. Represents the sound pressure level in each direction in increments of 30 degrees.

  A method for calculating the virtual sound source direction angle of the synthesized sound will be described.

  The sound pressure levels measured in increments of 30 degrees are P1, P2,..., P12, and the differences between the desired sound source direction angle θ and the angles in increments of 30 degrees are θ1, θ2,. Then, (Equation 3) is expanded and

What is necessary is just to obtain | require (theta) in which.

  The level of the synthesized sound is

Is required.

  The level adjuster group 260 is controlled to control the level adjuster 261 so that the virtual sound source direction angle θ obtained as described above approaches, for example, a desired installation angle 60 degrees of the virtual speaker 411 (VFL speaker). The distribution ratio of the coefficients K61 and 63 of H.263 is adjusted. By repeating this measurement and adjustment, the virtual sound source direction angle is finally controlled to coincide with the desired installation angle. For the other virtual speakers (VSL, VFR, VSR, VBL, VBR speakers), similarly, the level adjuster group 260 is controlled to adjust the coefficient distribution ratio of each level adjuster.

  In addition, the calculation of θ from (Equation 4) is complicated because the number of parameters is large and the calculation is complicated. Therefore, the measurement result from the microphone installed at an angle close to the installation angle of the speaker to be measured is appropriately selected. It may be used.

  Note that the C, FL, FR, SL, and SR speakers that are actual speakers do not have a function of adjustment in the signal processing unit 200, and therefore the virtual sound source direction angle obtained by the measurement unit 600 is the desired speaker position. The actual position of the actual speaker may be moved so that

  Further, the level adjuster group 220 is controlled for each speaker including the real speaker and the virtual speaker so that the level of the synthesized sound obtained in the above (Equation 5) becomes uniform, and the level adjusters 221 to 231 are controlled. The distribution ratio of the coefficients K21 to 31 is adjusted.

  As described above, for each speaker including the real speaker and the virtual speaker, the speaker position of the synthesized sound that can be actually heard is adjusted to the desired speaker position, and the level of the synthesized sound that can be actually heard becomes uniform. By adjusting in this way, a seamless sound field feeling without a joint can be obtained.

  As described above, in the sound reproduction device according to Embodiment 1 of the present invention, the input audio signal is equalized and delayed, and distributed and added to the arranged speakers. 11.1 Speaker assignment that realizes a channel speaker and reproduces each channel signal so as to obtain a desired reproduction sound field on the basis of the arrival sound pressure characteristics at predetermined angle increments at the viewing point of each speaker and the reproduction level By performing the control, a desired sound image localization and presence can be obtained.

  In the first embodiment, the virtual speaker is generated in the same horizontal plane as the real speaker. However, the equalizer characteristic is determined using the head-related transfer characteristic in the elevation direction (upward), and the virtual speaker is moved upward. You may form in.

  In the first embodiment of the present invention, the speaker configuration arranged on the same circumference has been described, but it goes without saying that other speaker arrangements can be similarly configured.

  Note that (first speaker, second speaker, and virtual speaker) in the present invention are (FL speaker, SL speaker, and VFL speaker), (FL speaker, SL speaker, and VSL speaker), and (FR) in the present embodiment. It corresponds to (speaker, SR speaker and VFR speaker), (FR speaker, SR speaker and VSR speaker), (SL speaker, SR speaker and VBL speaker), or (SL speaker, SR speaker and VBR speaker).

(Embodiment 2)
The operation and components of the sound reproducing device according to Embodiment 2 of the present invention will be described in detail below.

  Since most of the configuration is the same as that of the sound reproducing device according to the first embodiment of the present invention, only different portions will be described.

  In the second embodiment of the present invention, as in the first embodiment, the incoming sound in increments of 30 degrees at the viewing point of each speaker is measured with the microphone 500, and the sound pressure characteristic of the synthesized sound is obtained from this measured value. It controls so that the sound pressure in each speaker including a real speaker and a virtual speaker becomes uniform.

  On the other hand, since the person who actually watches has the head and pinna, the acoustic characteristics (frequency characteristics, directivity characteristics, etc.) of the auditory sound and the measurement microphone are not the same. In general, because of the structure of the head and earlobe, humans are less sensitive to sounds from the back, so a control method that uses only the microphone measurement results seems to make the reproduced sound in the front strong. An uncomfortable feeling may occur.

  Therefore, a control method according to human auditory characteristics will be described. In the measurement unit 600, the reproduction sound collected by the microphone 500 in increments of 30 degrees is subjected to frequency characteristics obtained from the head transfer characteristics in increments of 30 degrees with the center channel direction set to zero degrees as shown in FIG. As a frequency characteristic processing method, there are a method of processing by simulating the frequency characteristic with an equalizer (parametric, graphic, etc.), and a method of calculating an impulse response from the head transmission characteristic and performing a convolution process (time axis or frequency axis). Conceivable. In this way, the sound pressure characteristic is calculated from the reproduced sound in consideration of the head transmission characteristic. Based on this sound pressure characteristic, the desired sound field that matches well with the subjectivity can be reproduced by determining the signal reproduced from each speaker and its intensity in the same manner as in the first embodiment of the present invention. .

(Embodiment 3)
Hereinafter, the operation and components of the sound reproducing device according to Embodiment 3 of the present invention will be described in detail.

  Since most of the configuration is the same as that of the sound reproducing device according to the first embodiment of the present invention, only different portions will be described.

  In Embodiment 3 of the present invention, a microphone having an omnidirectional characteristic is used for measurement as the microphone 500. Since the microphone has an omnidirectional characteristic having uniform sound pressure characteristics in all directions of 360 degrees, measurement is performed by rotating the microphone in increments of 30 degrees like the unidirectional characteristic microphone described in the first embodiment of the present invention. Even if the microphones are rotated in increments of 30 degrees, a meaningful result cannot be obtained. Specifically, a plurality of omnidirectional microphones are combined to control the directional characteristic to a unidirectional characteristic and reproduced from each speaker in the same manner as in the first and second embodiments of the present invention. Determine the signal and its strength.

(Embodiment 4)
The operation and each component of the sound reproducing device according to Embodiment 4 of the present invention will be described in detail below.

  In the first embodiment, the level of the synthesized sound that can be actually heard is adjusted to be uniform for each speaker including the real speaker and the virtual speaker. However, depending on the preference of the source and the viewer, it is not necessarily uniform. Adjustment is not always optimal.

  Therefore, in the present embodiment, means for allowing the viewer to adjust the level of each speaker according to his / her preference is added to the measurement unit 600.

  Specifically, after adjusting the coefficient of each of the level adjusters 221 to 231 of the level adjuster group 220 by the method described in the first embodiment, the value of the level adjuster 221 to 231 is used as a reference, or 1 is set as the reference. The measuring unit 600 is provided with adjusting means that can increase or decrease according to preference.

  In particular, since the virtual speaker is created in a pseudo manner, there are some viewers who feel that it is more natural to play at a slightly lower level than at the same level as the real speaker.

  FIG. 8 shows an image of the sound pressure characteristics of the reproduced sound that arrives at the viewing point in 30 degree increments of each speaker when such a viewer adjusts the level of the virtual speaker to be 3 dB lower than the actual speaker. Indicates.

  According to the sound reproducing device of the present invention, a 5.1 channel speaker configuration is used without being influenced by the positional relationship between the speaker and the viewer, and further, reproduction from the speaker is performed without impairing the surround feeling of the content. This makes it possible to feel seamless surround in all directions without being conscious of what is being done, and full-scale sound field reproduction with a small number of speakers (sound field reproduction equivalent to movie theaters and movie production sites) This is particularly effective in expanding the market for home theaters where simple operation is desired.

DESCRIPTION OF SYMBOLS 100 Signal generation part 200 Signal processing part 210 Switch group 211-217 Switch 220 Level adjuster group 221-231 Level adjuster 241-252 Delay equalizer 260 Level adjuster group 261-272 Level adjuster 281-284 Adder 300 Power amplification Unit 401 to 406 speaker 411 to 416 virtual speaker 500 microphone 600 measuring unit

Claims (6)

A signal processing unit that processes the first input signal and the second input signal and outputs the processed signal to the first speaker and the second speaker;
The virtual sound source direction angle of the synthesized sound obtained by synthesizing the direct sound and the indirect sound coming from the first speaker and the second speaker to the viewing point is measured, and based on the measured virtual sound source direction angle. A measurement unit for controlling the signal processing unit,
The signal processing unit equalizes the first input signal with a first equalizer characteristic, delays it with a first delay characteristic, and adjusts the level with a first coefficient, and the first signal processor, A second signal processor that equalizes the input signal with the second equalizer characteristic, delays it with the second delay characteristic, and adjusts the level with the second coefficient, and adjusts the level of the first input signal with the third coefficient A first adder that adds the output signal and the output signal of the first signal processor and outputs the first signal to the first speaker; a signal obtained by adjusting the level of the second input signal by a fourth coefficient; and A second adder that adds the output signal of the second signal processor and outputs it to the second speaker;
The measurement unit controls the signal processing unit so that the third coefficient and the fourth coefficient become zero during measurement, and the virtual sound source direction angle is determined by the first speaker. The distribution ratio between the first coefficient and the second coefficient of the signal processing unit is controlled so that the angle of the virtual speaker is assumed at a predetermined position between the first speaker and the second speaker. A sound reproducing device. The measurement unit measures a sound pressure characteristic of the synthesized sound that arrives at the viewing point at a predetermined angle using at least one microphone having a unidirectional characteristic, and based on the measurement result, the virtual part The sound reproduction apparatus according to claim 1, wherein the sound source direction angle is calculated. 3. The measurement unit according to claim 2, wherein the measurement unit equalizes the sound pressure characteristic measured by the microphone with the frequency characteristic of the head-related transfer characteristic in increments of the predetermined angle as the measurement result. Sound playback device. The first equalizer characteristic is a characteristic obtained by dividing the head-related transfer function from the virtual speaker to the viewing point by the head-related transfer function from the first speaker to the viewing point,
The second equalizer characteristic is a characteristic obtained by dividing a head-related transfer function from the virtual speaker to the viewing point by a head-related transfer function from the second speaker to the viewing point. The sound reproducing device according to 1. The signal processing unit adjusts the level of the first signal by a fifth coefficient and supplies the first signal to the first signal processor and the second signal processor,
The sound reproducing apparatus according to claim 1, wherein the measurement unit includes an adjustment unit that can be adjusted by a viewer for changing the fifth coefficient of the signal processing unit. The first speaker and the second speaker are front L channel speakers and surround L channel speakers, front R channel speakers and surround R channel speakers, or surround L channel speakers and surround R in a 5.1 channel speaker configuration. The sound reproducing apparatus according to claim 1, wherein the sound reproducing apparatus is a channel speaker.