JP2009212944A - Acoustic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acoustic apparatus capable of giving a surround feeling to a listener by raising the stereotactic feeling of rear-side virtual sound sources when surround sound is reproduced in an acoustic apparatus. <P>SOLUTION: The acoustic apparatus 1 performs control to allow the listener to sense that the virtual sound source 24 of SLch is periodically moved by its prescribed time constant between the first point 24A and the second point 24B on the rear left side of the listener, and that the virtual sound source 25 of SRch is moved in the same way between the third point 25A and the fourth point 25B on the rear right side of the listener. When control is performed in this way, the positions of the virtual sound sources are normally moved without being fixed even when the listener is seated still on a chair, thereby obtaining an effect being the same as that where a person normally and slightly moves his/her head. That is, the acoustic apparatus 1 allows the listener to easily obtain the positions of the virtual sound sources and to have the stereotactic feeling of the virtual sound sources and also the surround feeling with the surround sound. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an acoustic device that reproduces a multi-channel surround sound from a real sound source using two speakers installed on the front side of a listener and a virtual sound source formed by the two speakers, and more particularly to a sense of localization of the virtual sound source. The present invention relates to an acoustic device that can be improved.

  Recently, by reproducing the sound on the front side and the sound on the rear side (surround sound) from two speakers installed on the front side of the listener, a plurality of virtual sound sources are localized on the rear side of the listener, An invention relating to an acoustic device capable of giving a listener a surround feeling (feeling of being surrounded) as if a plurality of speakers are arranged around the listener is disclosed (for example, see Patent Document 1).

In the virtual speaker amplifier described in Patent Document 1, for example, when reproducing surround sound of 5 channels (hereinafter referred to as “ch”), it is based on a head-related transfer function corresponding to a head shape data of a dummy head or a listener. The filter coefficient and the delay time are calculated by the DSP, and the filtering process and the crosstalk cancellation process are performed on the input SLch and SRch audio signals. Subsequently, the acoustic device adds the processed SLch and SRch audio signals to the Lch and Rch audio signals, respectively. Also, the acoustic device divides the Cch audio signal and adds it to the Lch and Rch audio signals. Then, the acoustic device emits Lch, Rch, divided Cch, and processed SLch and SRch sounds from the front side Lch speaker and the Rch speaker. As a result, the sound device has a Cch sound source at a point in the front center of the listener, a SLch sound source at a point on the left rear side of the listener, and a SRch sound source at a point on the right rear side of the listener. It is possible to give the listener a feeling of localization as if they were localized. Therefore, the listener can listen to the musical sound with a sense (surround feeling, surrounding feeling) that is surrounded by the surround sound by these virtual sound sources and the real sound sources of Lch and Rch.
Japanese Patent No. 3521900

  However, since the localization of each virtual sound source is fixed as a point in the conventional acoustic apparatus, the listener can determine where the rear SLch and SRch virtual sound sources are localized, particularly immediately after the sound is reproduced. I didn't understand. Therefore, there is a problem that the listener cannot feel the surround sound even though the surround sound is reproduced by the audio device.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an audio device that can provide a listener with a sense of surround by improving the sense of localization of a virtual sound source on the rear side when playing a surround sound with an audio device. .

  The present invention has the following configuration as means for solving the above problems.

(1) An acoustic device to which two speakers arranged in the vicinity of a listener are connected,
Based on the head-related transfer function, a frequency characteristic that can be heard by the listener's ear is calculated so that the localization position of the audio signal is moving within a predetermined region in a predetermined cycle, and is added to the audio signal and output. Filtering means;
Based on the head-related transfer function, a frequency characteristic for canceling a frequency characteristic of an audio signal arriving at one of the listener's ears from one of the two speakers is calculated based on the head signal. Direct correction means for outputting the frequency characteristics to the audio signal; and
Based on the head-related transfer function, a frequency characteristic obtained by inverting the frequency characteristic of the audio signal that circulates from one of the two speakers to the other ear of the listener is output to the audio signal output by the filter processing unit. Cross correction means for giving the frequency characteristics to the audio signal and outputting it,
Amplifying means for amplifying the audio signal output by the direct correction means and supplying the amplified audio signal to one of the two speakers; amplifying the audio signal output by the cross correction means for supplying to the other of the two speakers;
It is provided with.

  In this configuration, the acoustic device provides the audio signal with a frequency characteristic that can be heard by the listener as if the localization position of the audio signal is moving within a predetermined region at a predetermined period, and the audio signal is transmitted to one of the listeners. Crosstalk cancellation processing is performed by the direct correction means and the cross correction means so that only the ear can hear, and the audio signal is emitted from the two speakers to the listener. Therefore, the listener can easily perceive the localization position of the virtual sound source because the localization position of the audio signal seems to move within a certain area with a predetermined period.

(2) Amplifying means for amplifying and supplying an audio signal of multi-channel surround sound to an L-channel speaker and an R-channel speaker arranged on the front side of the listener;
The surround channel audio signal is filtered so that the listener senses that the surround channel audio signal of the multi-channel surround sound is moving in a predetermined period within a predetermined area on the rear side of the listener. Filtering means for performing
A crosstalk cancellation correcting unit that performs a crosstalk cancellation process on the audio signal of the surround channel that has been subjected to the filtering process, and outputs an audio signal to the amplification unit;
It is provided with.

  In this configuration, the audio device performs a filtering process on the audio signal of a specific channel so that a listener can detect that the signal is moving within a predetermined region at a predetermined period, and a crosstalk cancellation process. The audio signal of this specific channel is supplied to the L channel speaker and the R channel speaker. Therefore, since the listener can perceive that the virtual sound source localized around the listener is moving within a predetermined region in a predetermined cycle, the listener can easily perceive the localization position of the virtual sound source, This sound can be heard while feeling the siege by the multi-channel surround sound reproduced by the sound device.

(3) The filter processing means includes:
First localization means for performing filtering and outputting so that the audio signal is localized at a first point;
Second localization means for performing filtering and outputting so that the audio signal is localized at a second point;
Based on the time constant τ, the addition ratio of the audio signals output from the first localization means and the second localization means is periodically changed, and both audio signals are added and output to the crosstalk cancellation correction means. Dynamic addition means;
It is provided with.

  In this configuration, the acoustic apparatus uses the dynamic addition means to set the audio signal addition ratio output from the first localization means and the second localization means to the audio signal level and balance of each channel of the multichannel surround sound and the time constant τ. The two audio signals are added and output periodically. Therefore, it is possible to give the listener a feeling of localization such that the localization position of the audio signal periodically moves between the first point and the second point, and the localization position of the virtual sound source can be given to the listener. Can be perceived in a short time.

  (4) The dynamic addition means further detects the level and balance of the audio signal of each channel of the multi-channel surround sound, and based on the detection result and the time constant τ, the first localization means and The addition ratio of the audio signal output from the second localization means is periodically changed.

  In this configuration, the level and balance of the audio signal of each channel of the multi-channel surround sound is detected, and the audio signal output from the first localization means and the second localization means based on the detection result and the time constant τ. Thus, the localization position of the audio signal can be moved based on the level and balance of the audio signal of each channel. Therefore, even when the level or balance of the audio signal changes suddenly, it is possible to control so that the localization position of the audio signal does not move suddenly.

(5) The filter processing means includes:
Localization means for performing a filtering process so that the audio signal is localized at a plurality of different points within a fixed region;
Localization position switching means for detecting the level and balance of the audio signal of each channel and periodically switching the localization position of the virtual sound source of the specific channel based on the detection result and the time constant τ;
It is provided with.

  In this configuration, the localization position of the audio signal is periodically switched by the localization position switching means. Therefore, since the position where the audio signal can be heard changes periodically, the listener can quickly grasp the localization position of the virtual sound source.

  The acoustic device of the present invention can localize the virtual sound source not as a point but as a line or a surface by moving the position of the virtual sound source. Therefore, when the listener listens to the musical sound, the acoustic device of the present invention can make the listener perceive the position of the virtual sound source in a short time and feel a surround feeling (enclosed feeling).

  FIG. 1 is a block diagram illustrating a configuration of an audio device according to an embodiment of the present invention. As an example, it is assumed that the acoustic device 1 reproduces 5-channel surround sound. Also, in the following description, for each channel of the 5-channel surround sound, the front left channel is L (Left) ch, the front right channel is R (Right) ch, the center channel is C (Center) ch, and the rear channel is The left channel is referred to as SL (Surround Left) ch, and the rear right channel is referred to as SR (Surround Right) ch.

  Here, it is said that one of the factors that enables a person to grasp the front and back positions of a sound source even though there are only two ears is because the person always moves his head slightly. If you are sitting and listening to music without moving your head, you may not know where the rear virtual sound source is located. In the acoustic apparatus 1 of the present invention, in order to solve this problem, the SRch virtual sound source 24 is between the first point 24A and the second point 24B on the left rear side of the listener, and the SRch virtual sound source 25 is Control is performed so as to reciprocate between the third point 25A and the fourth point 25B on the right rear side of the listener while periodically moving with a predetermined time constant. By controlling in this way, even if the listener sits still on the chair, the position of the virtual sound source always moves without being fixed, so the same effect as if the person is always moving his head slightly is obtained. Can do. That is, the acoustic device 1 can make the listener easily grasp the position of the virtual sound source, and can give the listener a sense of localization of the virtual sound source, and further, a sense of siege by surround sound.

  Details of the present invention will be described below. The audio device 1 includes a DSP (Digital Signal Processor) decoder 11, a signal processing unit 12, a D / A converter 13, an electronic volume 15, a power amplifier 16, a controller 17, a memory 18, an operation unit 19, and a display unit 20. Yes. Further, an Lch speaker 21 and an Rch speaker 22 are connected to the power amplifier 16 of the acoustic device 1.

  As shown in FIG. 1, an L channel (hereinafter referred to as “ch”) and Rch speakers 21 and 22 are arranged in the room 91 as front speakers at the front left and front right of the listening position 90 of the listener U. Has been. Also, the acoustic device 1 localizes the SLch virtual sound source 24 between the first point 24A and the second point 24B on the left rear side of the listening position 90 of the listener U, so that the listening position 90 of the listener U is set. The SRch virtual sound source 25 is localized between the rear right third point 25A and the fourth point 25B, and the Cch virtual sound source 23 is localized at the front center of the listening position 90 of the listener U.

  The DSP decoder 11 is connected to a digital interface represented by a digital audio interface receiver (DIR) 32, an A / D converter 34, and a high definition multimedia interface (HDMI) (registered trademark) receiver 36. The DSP decoder 11 is an analog sound signal or digital bit output from an AV device such as the tuner 2 connected via the A / D converter 34 or the DVD player 3 connected via the HDMI (registered trademark) receiver 36. The stream is converted into a 5-channel digital sound signal (PCM signal) of Lch, Rch, Cch, SLch, and SRch and output to the signal processing unit 12. The DSP decoder 11 supports various data formats such as AAC (registered trademark), Dolby Digital (registered trademark), DTS (registered trademark), MPEG-1 / 2, MPEG-2 multi-channel, MP3, and the like. The external input signal is decoded into a 5-channel digital audio signal (PCM signal) by a decoder (not shown). For example, when a 5-channel digital audio signal (PCM signal) is directly input from the DVD player 3, the DSP decoder 11 outputs these signals as they are to the signal processing unit 12.

  The signal processing unit 12 includes an SLch first localization adding unit 42, an SLch second localization adding unit 44, an SRch first localization adding unit 46, an SRch second localization adding unit 48, an input signal detection unit 50, and an SLch dynamic addition unit 52. , An SRch dynamic addition unit 54, an Lch direct correction unit 62, an Lch cross correction unit 64, an Rch direct correction unit 66, an Rch cross correction unit 68, and adders 72 to 75 constituting the crosstalk cancellation correction unit 60. ing. Here, the DSP decoder 11 and the signal processing unit 12 may be constituted by one DSP or different DSPs.

  The signal processing unit 12 performs an operation for localizing the SLch virtual sound source 24 to the first point 24A on the left rear side of the listener U and an operation for localizing the SLch virtual sound source 24 to the second point 24B on the left rear side of the listener U. Then, the SLch virtual sound source 24 is localized between the first point 24A and the second point 24B by adding both calculation results at a predetermined ratio. In addition, the signal processing unit 12 periodically changes the addition ratio with a time constant of, for example, 30 seconds to 1 minute, so that the SLch virtual sound source 24 is generated between the first point 24A and the second point 24B. It is moved periodically at a predetermined speed.

  Similarly, the signal processing unit 12 localizes the SRch virtual sound source 25 to the third point 25A on the right rear side of the listener U and the fourth point 25B on the right rear side of the listener U. The calculation is performed, and both calculation results are added at a predetermined ratio to localize the SRch virtual sound source 25 between the third point 25A and the fourth point 25B. In addition, the signal processing unit 12 periodically changes the summing ratio with a time constant such as 30 seconds to 1 minute, so that the SRch virtual sound source 25 is generated between the third point 25A and the fourth point 25B. It is moved periodically at a predetermined speed.

  Specifically, each unit of the signal processing unit 12 performs the following operation. The SLch first localization adding unit 42 is set with a filter coefficient and a delay time based on a model head-related transfer function corresponding to the dummy head or the listener's head shape data. The listener U at position 90 is given to the SLch audio signal a frequency characteristic that the SLch sound can be heard from the SLch virtual sound source 24 localized at the first point 24A. Then, the SLch first localization adding unit 42 outputs the SLch audio signal to the SLch dynamic adding unit 52.

  Similarly, the SLch second localization adding unit 44 is set with a filter coefficient and a delay time based on a model head transfer function corresponding to the dummy head or the listener's head shape data, and performs convolution based on these. Then, the listener U at the listening position 90 is given to the SLch audio signal a frequency characteristic that the SLch sound can be heard from the SLch virtual sound source 24 localized at the second point 24B. Then, the SLch second localization adding unit 44 outputs the SLch audio signal to the SLch dynamic adding unit 52.

  The SRch first localization adding unit 46 is set with a filter coefficient and a delay time based on the model head transfer function corresponding to the dummy head or the listener's head shape data. The listener U at the position 90 is given to the SRch audio signal a frequency characteristic that the SRch sound can be heard from the SRch virtual sound source 25 localized at the third point 25A. Then, the SRch first localization adding unit 46 outputs the SRch audio signal to the SRch dynamic adding unit 54.

  The SRch second localization adding unit 48 is set with a filter coefficient and a delay time based on the model head transfer function corresponding to the dummy head or the listener's head shape data, and performs convolution based on these to perform listening. The listener U at position 90 is given to the SRch audio signal a frequency characteristic that the SRch sound can be heard from the SRch virtual sound source 25 localized at the fourth point 25B. The SRch second localization adding unit 48 outputs the SRch audio signal to the SRch dynamic adding unit 54.

  The input signal detection unit 50 detects the level and balance of the audio input signal of each channel (Lch, Rch, Cch, SLch, and SRch) of the surround sound output from the DSP decoder 11. Then, the input signal detection unit 50 periodically changes the addition ratio between the audio signal output from the SLch first localization adding unit 42 and the audio signal output from the SLch second localization adding unit 44. Based on the level and balance of the audio input signal and a preset time constant τ1, a SLch addition ratio coefficient α (0 ≦ α ≦ 1) whose value gradually changes is generated, and SLch motion To the automatic adder 52. Further, the input signal detection unit 50 periodically changes the addition ratio between the audio signal output from the SRch first localization adding unit 46 and the audio signal output from the SRch second localization adding unit 48. Based on the level and balance of the audio input signal and a preset time constant τ2, an SRch addition ratio coefficient β (0 ≦ β ≦ 1) whose value gradually changes is generated, and SRch It outputs to the dynamic addition part 54.

  Note that the SLch addition ratio coefficient α and the SRch addition ratio coefficient β are generated based on the time constants τ1 and τ2 for the audio signal of a specific channel when the level and balance of the audio input signal do not change so much. It is also possible to make it.

  The SLch dynamic addition unit 52 adds the audio signal output from the SLch first localization adding unit 42 and the SLch second localization addition at an addition ratio based on the coefficient α of the SLch addition ratio output from the input signal detection unit 50. The audio signal output from the unit 44 is added to generate an SLch added audio signal. Then, the SLch dynamic addition unit 52 outputs the SLch addition audio signal to the Lch direct correction unit 62 and the Lch cross correction unit 64.

  The SRch dynamic addition unit 54 adds the audio signal output from the SRch first localization adding unit 46 and the SRch second localization addition unit at an addition ratio based on the SRch addition ratio coefficient β output from the input signal detection unit 50. The audio signal output from 48 is added to generate an SRch added audio signal. The SRch dynamic addition unit 54 outputs the SRch addition audio signal to the Rch direct correction unit 66 and the Rch cross correction unit 68.

  Here, the audio signal output from the SLch first localization adding unit 42 is A, the audio signal output from the SLch second localization adding unit 44 is B, and the audio signal output from the SRch first localization adding unit 46 is C. D, the audio signal output from the SRch second localization adding unit 48, E, the SLch addition audio signal output from the SLch dynamic addition unit 52, and the SRch addition audio signal output from the SRch dynamic addition unit 54. Assuming F, the SLch dynamic addition unit 52 and the SRch dynamic addition unit 54 perform calculations based on the following equations.

E = αA + (1-α) B, F = βC + (1-β) D
FIG. 2 is a diagram illustrating localization positions of the SLch virtual sound source and the SRch virtual sound source. As shown in FIG. 2A, the first point 24A and the second point 24B are preferably positioned so that the open angle θL with respect to the listener is an arbitrary angle between 10 degrees and 30 degrees. . Similarly, the third point 25A and the fourth point 25B may be localized so that the opening angle θR with respect to the listener is an arbitrary angle between 10 degrees and 30 degrees.

  Further, the localization positions of the SLch virtual sound source 24 and the SRch virtual sound source 25 are the opening angle θ between the localization position of the SLch virtual sound source 24 and the localization position of the SRch virtual sound source 25 as shown in FIGS. Or may be controlled so as to change as shown in FIGS. 2D and 2E. Further, the time constant τ1 and the time constant τ2 may be set to the same value or different values.

  Further, the midpoint between the first point 24A and the second point 24B and the midpoint between the third point 25A and the fourth point 25B are ITU-R BS. The SLch and SRch positions recommended in 775-1 may be set.

  Here, for example, when the SLch sound is emitted from the Lch speaker 21 and this sound is heard from both ears to the listener U, the listener U has emitted the SLch sound from the Lch speaker 21. Can be easily identified. However, with respect to the SLch audio signal, the frequency characteristics of the sound that is emitted from the sound source localized at the rear left side of the listener U and reaches the ear of the listener U, and the sound that is emitted from the Lch speaker 21 are heard. When a frequency characteristic that cancels the frequency characteristic of the voice that reaches the left ear EL of U is applied based on the model head-related transfer function and is emitted from the Lch speaker 21, the listener U hears the voice from the rear left side. I feel like I can hear. At this time, if a sound that cancels the sound that is emitted from the Lch speaker 21 and propagates to the right ear of the listener U is generated and emitted from the Rch speaker 22, the listener U receives the SLch sound. The sound emitted from the Lch speaker 21 is not perceived, and the sound emitted from the Lch speaker 21 can be heard only by the left ear of the listener U. Therefore, in the audio device 1, the crosstalk cancellation correction unit 60 is selected so that the sound emitted from one of the two selected speakers can be heard in a flat characteristic only by one ear of the listener U. A crosstalk cancellation process is performed to generate a sound that cancels the sound heard by the other ear so that the sound emitted from the other of the two speakers can be heard only by the other ear of the listener U with a flat characteristic. Specifically, the following processing is performed.

  FIG. 3 is a graph of frequency characteristics for explaining the correction processing in the crosstalk cancellation correction unit. FIG. 3A is a graph showing frequency characteristics of sound propagating from the Lch speaker to the left ear EL (direct) of the listener U and the right ear ER (cross) of the listener U. FIG. 3B is a diagram illustrating frequency characteristics applied by the Lch direct correction unit and the Lch cross correction unit in order to cancel the crosstalk of the sound propagating from the Lch speaker to both ears of the listener U. FIG. 3C is a graph showing the frequency characteristics of sound propagating from the Rch speaker to the right ear ER (direct) of the listener U and the left ear EL (cross) of the listener U. FIG. 3D shows the frequency characteristics of the sound that cancels the crosstalk of the sound propagating from the Lch speaker to the right ear ER (direct) of the listener U and the left ear EL (cross) of the listener U. FIG. 4 is a conceptual diagram for explaining the crosstalk cancellation processing and a block diagram showing details of the crosstalk cancellation correction unit.

  When a sound having a flat frequency characteristic is emitted from the Lch speaker 21, the sound reaching the left ear EL of the listener U attenuates each frequency component and the frequency characteristic as shown in (1) of FIG. It becomes. Therefore, the listener U can unconsciously determine that the SLch sound is emitted from the Lch speaker 21 based on the frequency characteristics.

On the other hand, the Lch direct correction unit 62 is set with a filter coefficient corresponding to the inverse function of the model head-related transfer function from the Lch speaker 21 to the left ear EL of the listener U. That is, as shown in FIG. 4, the model head related transfer function from the Lch speaker 21 to the listener's left ear EL and the model head related transfer function from the Rch speaker 22 to the listener's right ear ER are expressed as fd. Lch direct correction when the model head-related transfer function from the Lch speaker 21 to the listener's right ear ER and the model head-related transfer function from the Rch speaker 22 to the listener's U left ear EL are fc The filter coefficient set in the unit 62 is fd / (fd ² −fc ² ). The Lch direct correction unit 62 gives frequency characteristics shown in (1) of FIG. 3B to the SLch audio signal output from the SLch dynamic addition unit 52. As a result, the Lch direct correction unit 62 can eliminate the characteristic of propagation from the Lch speaker 21 to the left ear EL so that the listener U does not perceive that the SLch sound is emitted from the Lch speaker 21. can do. Accordingly, when the SLch audio sound is emitted from the Lch speaker 21 and propagates to the left ear EL of the listener U, each frequency component attenuates as described above, but the Lch direct correction unit 62 preliminarily reduces the amount of attenuation. Raised. As a result, the audio signal output from the Lch direct correction unit 62 is localized between the first point 24A and the second point 24B on the left rear of the listening position 90 given by the SLch dynamic addition unit 52. It has a frequency characteristic that can be heard from the SLch virtual sound source 24 and a frequency characteristic that cancels the characteristic that propagates from the Lch speaker 21 to the left ear EL.

The Lch cross correction unit 64 prevents the audio sound that is emitted from the Lch speaker 21 shown in (2) of FIG. 3A and propagates (wraps around) the right ear ER of the listener U from being heard. This is for generating a sound that cancels the audio sound that wraps around the ear ER, and for emitting an audio sound having a frequency characteristic that can be heard from the SLch virtual sound source 24 from the Rch speaker 22. In other words, the Lch cross correction unit 64 performs the inverse function of the head-related transfer function from the Lch speaker 21 to the listener's U left ear EL and the head-related transfer function from the Lch speaker 21 to the listener's U right ear ER. Is set to a filter coefficient fc / (fd ² −fc ² ) corresponding to the product of the inverse function of. The Lch cross correction unit 64 performs the same process as the Lch direct correction unit 62 raises the level of the SLch audio signal in advance by an attenuation amount, and an audio signal that wraps around from the Lch speaker 21 to the right ear ER of the listener U The frequency characteristic obtained by inverting the frequency characteristic is calculated based on the model head-related transfer function, the frequency characteristic is added to the SLch audio signal, and is propagated from the Lch speaker 21 to the right ear ER of the listener U. 3 and the process of making the SLch audio signal audible to the right ear ER of the listener U. The SLch summed audio signal output from the SLch dynamic adder 52 is shown in FIG. A frequency characteristic indicated by cross in (2) of B) is given. The Lch cross correction unit 64 performs the above-described processing on the SLch addition audio signal output from the SLch dynamic addition unit 52, adds the phase by the inversion / adder 73 in the buffer 65, and releases it from the Rch speaker 22. The timing at which the SLch added audio signal propagates to the right ear ER of the listener U after the sound, and the SLch added audio signal that is processed by the Lch direct correction unit 62 and the like and emitted from the Lch speaker 21 are output to the right ear ER of the listener U. The output timing of the SLch added audio signal is adjusted so that the timing at which the signal is propagated to is the same.

  Similarly, when sound having a flat frequency characteristic is emitted from the Rch speaker 22, the sound reaching the right ear ER of the listener U is attenuated at each frequency component in the center symmetrical position of the speaker. The frequency characteristics as shown in (1) of FIG. Therefore, the listener U can unconsciously determine that SRch sound is emitted from the Rch speaker 22 based on the frequency characteristics.

On the other hand, the Rch direct correction unit 66 is set with a filter coefficient corresponding to the inverse function of the model head-related transfer function from the Rch speaker 22 to the right ear ER of the listener U. That is, as shown in FIG. 4, the filter coefficient set in the Rch direct correction unit 66 is fd / (fd ² −fc ² ). The Rch direct correction unit 66 gives the frequency characteristics shown in (1) of FIG. 3D to the SRch audio signal output from the SRch dynamic addition unit 54. As a result, the Rch direct correction unit 66 can eliminate the characteristic of propagation from the Rch speaker 22 to the right ear ER so that the listener U does not perceive that the SRch sound is emitted from the Rch speaker 22. can do. Therefore, when the SRch audio sound is emitted from the Rch speaker 22 and propagates to the right ear ER of the listener U, each frequency component is attenuated as described above. Since the bottom is raised, the frequency characteristic that can be heard from the SRch virtual sound source 25 located between the third point 25A and the fourth point 25B on the right rear side of the listening position 90 given by the SRch dynamic adding unit 54 Become.

The Rch cross correction unit 68 prevents the audio sound that is emitted from the Rch speaker 22 shown in (2) of FIG. 3C and propagates (wraps around) the left ear EL of the listener U from being heard. This is for generating a sound that cancels out the audio sound that wraps around the ear EL, and for emitting an audio sound of frequency characteristics that can be heard from the SRch virtual sound source 25 from the Lch speaker 21. In other words, the Rch cross correction unit 68 performs the inverse function of the model head transfer function from the Rch speaker 22 to the right ear ER of the listener U and the model head transfer function from the speaker 22 to the left ear EL of the listener U. Is set to a filter coefficient fc / (fd ² −fc ² ) corresponding to the product of the inverse function of. The Rch cross correction unit 68 performs the same processing as the Rch direct correction unit 66 raising the level of the SRch audio signal in advance by the amount of attenuation, and the audio signal that circulates from the Rch speaker 22 to the left ear EL of the listener U A frequency characteristic obtained by inverting the frequency characteristic of the Rch speaker 22 is added to the SRch audio signal, and the characteristic of propagating from the Rch speaker 22 to the left ear EL is erased. 3, the SRch audio signal is heard by the left ear EL of the listener U, and the SRch summed audio signal output from the SRch dynamic adder 54 is 2) The frequency characteristic indicated by cross is given. The Rch cross correction unit 68 performs the above processing on the SRch addition audio signal output from the SRch dynamic addition unit 54, adds the phase by the inversion / adder 72 in the buffer 69, and releases it from the Lch speaker 21. The timing at which the SRch added audio signal propagates to the left ear EL of the listener U after the sound and the timing at which the SRch added audio signal propagates to the left ear EL after being output from the Rch speaker 22 after being processed by the Rch direct correction unit 66 and the like And the output timing of the SRch-added audio signal are adjusted so as to be the same.

  Therefore, the audio sound emitted from the Lch speaker 21 is heard only by the listener U's left ear EL, and the audio sound emitted from the Rch speaker 22 is heard only by the listener U's right ear ER. The listener U releases the sound of the SLch from the virtual sound source 24 that periodically moves at a predetermined speed between the first point 24A and the second point 24B, and the sound of the SRch becomes the third point. It is possible to obtain a sense of localization as if sound is emitted from the virtual sound source 25 that periodically moves at a predetermined speed between 25A and the fourth point 25B.

  The adder 72 adds the audio signal output from the Lch direct correction unit 62 and the audio signal output from the Rch cross correction unit 68 and inverted (multiplied by −1) by the buffer 69. Output to 74.

  The adder 73 adds the audio signal output from the Rch direct correction unit 66 and the audio signal output from the Lch cross correction unit 64 and inverted (multiplied by −1) by the buffer 69. Output to 75.

  The adder 74 adds the Lch audio signal and the Cch audio signal output from the DSP decoder 11 and the audio signal output from the adder 72 and outputs the result to the D / A converter 13.

  The adder 75 adds the Rch audio signal and the Cch audio signal output from the DSP decoder 11 and the audio signal output from the adder 73 and outputs the result to the D / A converter 13.

  Here, the C-channel audio signal divided into two is input to the adders 74 and 75. Therefore, since the Lch speaker 21 and the Rch speaker 22 emit Cch sound at the same volume, the acoustic device 1 has the Cch virtual sound source 23 located between the Lch speaker 21 and the Rch speaker 22. It is possible to give the listener U a feeling of localization.

  The D / A converter 13 converts the digital sound signals of a total of five channels of Lch, Rch, Cch, SLch, and SRch output from the adders 74 and 75 of the signal processing unit 12 into analog sound signals, respectively.

  The electronic volume 15 adjusts the signal amount of the analog sound signal of each channel based on the control signal output from the controller 17 according to the operation of the operation unit 19.

  The power amplifier 16 amplifies the analog sound signal adjusted by the electronic volume 15 and outputs it to the Lch speaker 21 and the Rch speaker 22.

  The Lch speaker 21 and the Rch speaker 22 emit sound according to the analog sound signal output from the power amplifier 16. That is, the Lch speaker 21 emits Lch, Cch, and SLch sounds, and the Rch speaker 22 emits Rch, Cch, and SRch sounds.

  The controller 17 controls each unit in accordance with the operation performed on the operation unit 19. For example, when a volume adjustment operation is performed at the operation unit 19, the controller 17 outputs a control signal corresponding to this operation to the electronic volume 15 to change the volume of sound emitted from each speaker 21 to 27. The controller 17 is preferably a CPU or MPU.

  The memory 18 stores a program executed by the controller 17.

  The operation unit 19 is used by the user to input various operations and settings to the audio device 1.

  The display unit 20 is for displaying items transmitted from the audio device 1 to the user.

  As described above, in the audio device according to the embodiment of the present invention, a plurality of virtual sound sources are provided around the user, and the position where each virtual sound source is localized is detected by the listener so as to move at a predetermined cycle. Therefore, the listener can immediately perceive the sense of localization of the virtual sound source, and the listener can be given a sense of siege by surround sound. As a result, the user can listen to the musical sound while enjoying the siege by the surround sound.

  In the above description, the localization positions of the SLch and SRch are assumed to be two points, and the two points are periodically moved with a time constant τ. However, the present invention is not limited to this embodiment. It may be an embodiment. For example, a plurality of (three or more) localization points of SLch and SRch are provided in a predetermined area that does not give the listener a sense of incongruity even if the SLch and SRch are localized, and the localization position of the virtual sound source is continuous or discrete. In addition, it can be set to change at a constant cycle. Also in this case, the listener can easily perceive the localization position of the virtual sound source in a short time.

  Further, in the above description, the case where the localization position of the virtual sound source is moved only for the rear channel of the 5ch surround sound has been described. For example, the sound field processing disclosed in Japanese Patent Laid-Open No. 11-252698 is disclosed. Like the device, the front side channel can also be a virtual sound source. Therefore, by applying the present invention not only to the rear side but also to the front side virtual sound source and moving its localization position, the listener can easily grasp the localization position of the virtual sound source of each channel.

It is a block diagram which shows the structure of the audio equipment concerning embodiment of this invention. It is a figure which shows the localization position of the virtual sound source of SLch, and the virtual sound source of SRch. It is a graph of the frequency characteristic for demonstrating the correction process in a crosstalk cancellation correction | amendment part. It is the conceptual diagram for demonstrating a crosstalk cancellation process, and the block diagram which shows the detail of a crosstalk cancellation correction | amendment part.

Explanation of symbols

    1-acoustic device 11-DSP decoder 12-signal processing unit 13-D / A converter 15-electronic volume 16-power amplifier 17-controller 18-memory 19-operation unit 20-display unit 21-Lch speaker 22-Rch Speakers 23, 24, 25-virtual sound source 42-SLch first localization addition unit 44-SLch second localization addition unit 46-SRch first localization addition unit 48-SRch second localization addition unit 50-input signal detection unit 52-SLch Dynamic adder 54-SRch dynamic adder 60-Crosstalk cancellation corrector 62-Lch direct corrector 64-Lch cross corrector 66-Rch direct corrector 68-Rch cross corrector 72-75-Adder

Claims (5)

An acoustic device to which two speakers arranged in the vicinity of a listener are connected,
Based on the head-related transfer function, a frequency characteristic that can be heard by the listener's ear is calculated so that the localization position of the audio signal is moving within a predetermined region in a predetermined cycle, and is added to the audio signal and output. Filtering means;
Based on the head-related transfer function, a frequency characteristic for canceling a frequency characteristic of an audio signal arriving at one of the listener's ears from one of the two speakers is calculated based on the head signal. Direct correction means for outputting the frequency characteristics to the audio signal; and
Based on the head-related transfer function, a frequency characteristic obtained by inverting the frequency characteristic of the audio signal that circulates from one of the two speakers to the other ear of the listener is output to the audio signal output by the filter processing unit. A cross correction means for outputting the frequency characteristics to the audio signal;
Amplifying means for amplifying the audio signal output by the direct correction means and supplying the amplified audio signal to one of the two speakers; amplifying the audio signal output by the cross correction means for supplying to the other of the two speakers;
An acoustic device comprising: Amplifying means for amplifying and supplying an audio signal of multi-channel surround sound to an L channel speaker and an R channel speaker arranged on the front side of the listener;
The surround channel audio signal is filtered so that the listener senses that the surround channel audio signal of the multi-channel surround sound is moving in a predetermined period within a predetermined area on the rear side of the listener. Filtering means for performing
A crosstalk cancellation correction unit that performs a crosstalk cancellation process on the audio signal of the surround channel that has been subjected to the filtering process, and outputs an audio signal to the amplification unit;
An acoustic device comprising: The filter processing means includes
First localization means for performing filtering and outputting so that the audio signal is localized at a first point;
Second localization means for performing filtering and outputting so that the audio signal is localized at a second point;
Based on the time constant τ, the addition ratio of the audio signals output from the first localization means and the second localization means is periodically changed, and both audio signals are added and output to the crosstalk cancellation correction means. Dynamic addition means;
The acoustic device according to claim 1, further comprising:   The dynamic adding means further detects the level and balance of the audio signal of each channel of the multi-channel surround sound, and based on the detection result and the time constant τ, the first localization means and the second localization means. 4. The acoustic apparatus according to claim 3, wherein the addition ratio of the audio signal output from the localization means is periodically changed. The filter processing means includes
Localization means for performing a filtering process so that the audio signal is localized at a plurality of different points within a fixed region;
Localization position switching means for detecting the level and balance of the audio signal of each channel and periodically switching the localization position of the virtual sound source of the specific channel based on the detection result and the time constant τ;
The acoustic device according to claim 1, further comprising:

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