Acoustic control device and acoustic control method

Abstract

To provide an acoustic control device and acoustic control method capable of controlling sound sources whose number is larger than the number of control channels.SOLUTION: An acoustic control device includes: the N-channel (N is an integer equal to or more than two) of acoustic filters; a signal generation section; the L-number (L is a natural integer) of acoustic filters; and the M-number (M is N+L) of sound sources. The acoustic filters are applied with respect to an input sound signal. The signal generation section performs addition of N-number of first control sound source signals to be respectively output from the N-channel of acoustic filters by a predetermined ratio, so as to generate second control sound source signals having a phase of predetermined relation with respect to the N-number of first control sound source signals. The sound sources radiate sound based on the first control sound source signals to be respectively output from the N-channel of acoustic filters and the second control sound source signals to be respectively output from the L-number of signal generation sections.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to an acoustic control device and an acoustic control method. [Background technology]

[0002] A sound field control technology is known that places three or more sound sources and controls the spatial sound field around the sound source by adjusting the amplitude and phase of the sound emitted from each sound source. This sound field control technology can create areas where sound is inaudible or areas where sound is locally audible. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-048468 Summary of the Invention [Problem to be solved by the invention]

[0004] Most audio playback devices support two-channel (ch) control, but not multi-channel control of three or more channels. To use three or more sound sources, a separate audio interface that supports three or more channels is required. From the perspective of cost reduction, it is desirable to be able to control the amplitude and phase of three or more sound sources using two-channel control.

[0005] The embodiments provide an acoustic control device and an acoustic control method that can control a greater number of sound sources than the number of control channels. [Means for solving the problem]

[0006] An acoustic control device according to one aspect includes N-channel acoustic filters (N is an integer equal to or greater than two), a signal generator, L (L is a natural number) acoustic filters, and M (M is N+L) sound sources. The acoustic filters are applied to an input audio signal. The signal generator generates a second control sound source signal having a phase that has a predetermined relationship with the N first control sound source signals by adding N first control sound source signals output from the N-channel acoustic filters at a predetermined ratio. The sound source radiates sound based on the first control sound source signals output from the N-channel acoustic filters and the second control sound source signals output from the L signal generators. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of an acoustic control device according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating a configuration of an example of an R signal generating unit. [Figure 3] FIG. 3 is a block diagram showing elements included in the control device. [Figure 4] FIG. 4 is a diagram showing the gain characteristics of the acoustic filter coefficients qL, qC, and qR of equation (9). [Figure 5] FIG. 5 is a diagram showing the phase characteristics of the acoustic filter coefficients qL, qC, and qR. [Figure 6] FIG. 6 is a diagram showing a comparison between the gain characteristics of the L signal and C signal convolved with acoustic filter coefficients qL and qC and the gain characteristics of the R signal generated from the L signal and C signal. [Figure 7] FIG. 7 is a diagram showing a comparison between the phase characteristics of the L signal and C signal convolved with acoustic filter coefficients qL and qC and the phase characteristics of the R signal generated from the L signal and C signal. [Figure 8] FIG. 8 is a diagram showing an example of the configuration of an acoustic control device according to Modification 1 in which an audio signal processing device and a speaker are wirelessly connected. [Figure 9] FIG. 9 is a diagram illustrating an example of the configuration of the acoustic control device according to the second modification. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment will be described with reference to the drawings. Fig. 1 is a diagram showing an example of the configuration of an acoustic control device according to an embodiment. The acoustic control device 100 in Fig. 1 has an audio signal input unit 101, an audio signal processing device 102, a control device 103, amplifiers 104L, 104C, and 104R, and speakers 105L, 105C, and 105R.

[0009] The acoustic control device 100 can control the amplitude and phase of sound emitted from three speakers using two-channel (ch) control. For example, the acoustic control device 100 creates a spatial sound field in which sound is transmitted only to a specific area by using three speakers for sound boost control and acoustic power control. Sound boost control is a control that increases the sound pressure in a specific direction by controlling the amplitude of sound emitted from multiple speakers. On the other hand, acoustic power control is a control that reduces the acoustic power when multiple speakers are viewed as a single speaker by controlling the amplitude and phase of sound emitted from the multiple speakers.

[0010] The audio signal input unit 101 inputs an audio signal to the audio signal processing device 102. The audio signal input unit 101 may also input the audio signal to the control device 103. The audio signal is a signal that includes sound information. The audio signal is prepared in advance for playback, for example. The audio signal may be generated sequentially for each playback, or may be input by the user or the control device 103, for example.

[0011] The audio signal processing device 102 performs signal processing on an audio signal and includes acoustic filters 1021L and 1021C and an R signal generation unit 1022.

[0012] The acoustic filter 1021L filters the audio signal input from the audio signal input unit 101 using an acoustic filter coefficient q designated by the control device 103. LThen, the acoustic filter 1021L outputs the L signal obtained by filtering as a first sound source control signal to the amplifier 104L. Also, the acoustic filter 1021C filters the audio signal input from the audio signal input unit 101 according to the acoustic filter coefficient q C Then, acoustic filter 1021C outputs the C signal obtained by filtering as a first sound source control signal to amplifier 104C. These acoustic filters are intended to pass only sounds in a specific band of the audio signal.

[0013] The R signal generator 1022 generates an R signal from the L signal and the C signal as a second sound source control signal for the speaker 105R, and outputs the R signal to the amplifier 104R.

[0014] FIG. 2 illustrates an exemplary configuration of the R signal generating unit 1022. The R signal generating unit 1022 includes a mixer 1022a and a phase adjuster 1022b. The mixer 1022a mixes the L signal and the C signal at a predetermined ratio specified by the control device 103. As will be described later, the mixer 1022a mixes, for example, a 1:1 ratio of the L signal multiplied by 1 / 2 and the C signal multiplied by 1 / 2. The phase adjuster 1022b is a phase adjustment circuit that adjusts the phase of the R signal output from the mixer 1022a. As will be described later, the phase adjuster 1022b inverts the phase of the R signal output from the mixer 1022a by 180 degrees. The mixing ratio of the mixer 1022a can be changed as appropriate depending on the design. The mixer 1022a may include an amplifier or the like.

[0015] The control device 103 determines the acoustic filter coefficients q to be given to the acoustic filters 1021L and 1021C. L , q CThe control device 103 is a device configured by a computer including a processor and memory for calculating the gain to be given to the R signal generating unit 1022. The control device 103 may also set the gains of the amplifiers 104L, 104C, and 104R. The control device 103 will be described later.

[0016] Amplifier 104L amplifies the L signal by a gain specified by control device 103. Amplifier 104C amplifies the C signal by a gain specified by control device 103. Amplifier 104R amplifies the R signal by a gain specified by control device 103.

[0017] Speakers 105L, 105C, and 105R are connected by wire to audio signal processing device 102 via amplifiers 104L, 104C, and 104R, and are sound sources that emit sounds corresponding to input audio signals. Speaker 105L operates as the left speaker, speaker 105C operates as the center speaker, and speaker 105R operates as the right speaker. The positional relationship between the speakers is an example and can be changed as appropriate depending on the design.

[0018] Next, we will explain the control device 103. Fig. 3 is a block diagram showing elements included in the control device 103. The control device 103 has an acquisition unit 1031, an acoustic filter coefficient calculation unit 1032, an acoustic filter coefficient storage unit 1033, and an acoustic filter setting unit 1034.

[0019] The acquisition unit 1031 acquires various pieces of information necessary for calculating acoustic filter coefficients. Then, the acquisition unit 1031 inputs the acquired information to the acoustic filter coefficient calculation unit 1032. The information acquired by the acquisition unit 1031 includes, for example, information on frequency, speaker spacing, and transfer function.

[0020] The frequency is the frequency of the audio signal input from the audio signal input unit 101. The acquisition unit 1031 acquires, for example, frequency information from the audio signal input unit 101. Note that if the speed of sound c is known, the frequency can be converted into a wave number. The acquisition unit 1031 may acquire the wave number information from the audio signal input unit 101. Furthermore, if the frequency of the audio signal is a fixed value, the acquisition unit 1031 may input pre-stored information on the fixed value of the frequency to the acoustic filter coefficient calculation unit 1032.

[0021] The speaker spacing is the spacing between the speakers 105L, 105C, and 105R. The acquisition unit 1031 acquires the speaker spacing based on, for example, an input from a user. If the speakers are fixed, the speaker spacing may be treated as a fixed value. In this case, the acquisition unit 1031 may input information about the fixed speaker spacing stored in advance to the acoustic filter coefficient calculation unit 1032.

[0022] The transfer function is a function that represents the transfer characteristics of sound between each of the speakers 105L, 105C, and 105R and the volume increase control point, and is determined by the positional relationship between the speakers 105L, 105C, and 105R and the volume increase control point. The volume increase control point is the control target position for volume increase control. The transfer function represents the spatial transfer characteristics C of the sound transferred from the speaker 105L to the volume increase control point. L , spatial transmission characteristic C of the sound transmitted from the speaker 105C to the sound increase control point C , spatial transmission characteristic C of the sound transmitted from the speaker 105R to the sound increase control point RThe spatial transfer characteristics are expressed as a matrix with elements . Each spatial transfer characteristic can be measured from a microphone-acquired signal obtained by emitting a sound based on a random signal or a sound based on a TSP (Time Stretched Pulse) signal from the speakers 105L, 105C, and 105R in an anechoic room or listening room with little sound reflection, and collecting this sound with a microphone placed at the position of the volume increase control point. The acquisition unit 1031 acquires the transfer function measured in this manner. Note that if the positions of the speakers 105L, 105C, and 105R and the positions of the volume increase control points are fixed, the transfer function can be treated as a fixed transfer function. In this case, the acquisition unit 1031 may input a pre-stored fixed transfer function to the acoustic filter coefficient calculation unit 1032.

[0023] The acoustic filter coefficient calculation unit 1032 receives various information from the acquisition unit 1031 and also receives the acoustic filter coefficient for the speaker 105C from the acoustic filter coefficient storage unit 1033, and calculates the acoustic filter coefficient for the speaker 105L. Then, the acoustic filter coefficient calculation unit 1032 inputs the acoustic filter coefficient to the acoustic filter setting unit 1034.

[0024] The acoustic filter coefficient storage unit 1033 stores the acoustic filter coefficient q for the speaker 105C. C I remember.

[0025] The acoustic filter setting unit 1034 sets the acoustic filter coefficient q L is set as the acoustic filter 1021L, and the acoustic filter coefficient q C is set as the acoustic filter 1021C.

[0026] An example of acoustic filter coefficients in which sound increase control and sound power control are combined will be described below. In the following, sound increase control and sound power control will be described for three speakers 105L, 105C, and 105R arranged side by side as shown in Figure 1, where the sound increase control point is set in the front direction of speaker 105C.

[0027] First, acoustic power control will be described. When speakers 105L, 105C, and 105R arranged side by side as shown in Fig. 1 are viewed as one speaker, acoustic power W is expressed by the following equation (1).

number

[0028] Here, in equation (1), q L =α q C , q R =β q C where α and β are complex functions. In this case, equation (1) can be expressed as equation (2).

number

[0029] As shown in equation (2), acoustic power W is a function of the product kd of the wave number and the speaker spacing. Therefore, the amount of reduction in acoustic power W is determined by the kd value. When the value of kd, i.e., the frequency of the sound emitted from the speakers and the speaker spacing, is appropriately determined, the values ​​of sinc(kd) and sinc(2kd) in equation (2) can both be approximated to 1. In this case, equation (2) is approximated as in equation (3). As acoustic power W in equation (3) decreases, the spatial sound field around speakers 105L, 105C, and 105R becomes a quiet field.

number

[0030] As mentioned above, both α and β are complex functions. r +jα i , B=β r +jβ i After separating the real part and the imaginary part, the parentheses in equation (3) are rearranged, and the parentheses in equation (3) are expressed as equation (4).

number

[0031] In formula (4), for example, α i =-β i Let, and α r +β r The value of W is reduced by setting α=α r +jα i , β=β r +jβ i Therefore, the condition of the following equation (5) is obtained. α+β=1 (5)

[0032] where the acoustic filter coefficient q c is a fixed value stored in the acoustic filter coefficient storage unit 1033. For example, q c = 1, the acoustic filter coefficient q L , q C , q R is obtained as shown in the following equation (6): Equation (6) is a relational expression derived from the acoustic power control measurement. q L =α q C =1 q R =(1-α) (6)

[0033] Next, the volume increase control will be described. The volume increase control is a control for increasing the sound pressure at a volume increase control point. For example, the volume increase control is a control for increasing the sound pressure before volume increase control at one volume increase control point arranged in the front direction of the speaker 105C by P OFF , the sound pressure after the sound increase control is P ON , when the amplification factor is n, P ON =nP OFFIt can be controlled as follows. P OFF is the sound pressure at the sound increase control point when sound is emitted only from the speaker 105C, and the transfer function between the sound increase control point and the speaker 105C is D C , the complex volume velocity q of the sound radiated from the speaker 105C c When , P OFF =D C D C * ·q C On the other hand, P OFF is the sound pressure at the sound increase control point when sound is emitted from the speakers 105L, 105C, and 105R, and the transfer function between the sound increase control point and the speaker 105L is D L , the transfer function between the sound increase control point and the speaker 105C is D C , the transfer function between the sound increase control point and the speaker 105R is D R , the complex volume velocity q of the sound emitted from the speaker 105L L , the complex volume velocity q of the sound radiated from the speaker 105C c , the complex volume velocity q of the sound radiated from the speaker 105R R When P ON =D L D L * ·q L +D C D C * ·q C +D R D R * Therefore, from the sound increase control, the following equation (7) is obtained.

number

number

[0034] From equations (6) and (8), the filter coefficient q that can achieve both the sound power control and sound increase control effects is L , q C , q R is calculated as shown in equation (9).

number

[0035] Figure 4 shows the acoustic filter coefficient q L , q C , q R 5 is a diagram showing the gain characteristics of the acoustic filter coefficient q L , q C , q R 10 is a diagram showing the phase characteristic of the signal A. An FIR (finite impulse response) filter is calculated as an acoustic filter to be convoluted with the audio signal by performing an inverse Fourier transform on the product of the gain characteristic and the phase characteristic.

[0036] As shown in Figure 4, the acoustic filter coefficient q C The convolved C signal and the acoustic filter coefficients q L The gain of the L signal convolved with is almost the same in the range of 500Hz-3000Hz. As shown in Figure 5, the acoustic filter coefficient q C The convolved C signal and the acoustic filter coefficients q L The phase of the L signal convolved with is also almost the same in the range of about 500Hz-3000Hz. On the other hand, the acoustic filter coefficient q R The gain of the R signal convolved with is lower than the gains of the L and C signals in the range of 500 Hz to 3000 Hz. In addition, the phase of the R signal is almost inverse to that of the L and C signals.

[0037] Here, in a conventional 2-channel control signal processing device, three acoustic filter coefficients q L , q C , q RFor example, the L signal and the C signal can only be output to the speaker. Therefore, for the third speaker, the acoustic filter coefficient q is controlled by a signal processing device other than the 2ch control signal processing device. R are convolved and output to the speaker. In this case, the L signal and C signal are processed by the same signal processing device, so they have the desired phase characteristics shown in Figure 5. On the other hand, the R signal is processed by a different signal processing device, so there is a high possibility that its phase characteristics will deviate from the desired phase characteristics shown in Figure 5. The amount of phase shift between the R signal and the L and C signals differs each time processing is performed, making it difficult to correct.

[0038] In this embodiment, the acoustic filter coefficient q is calculated for the R signal by a separate signal processing device. R Instead of convoluting, the R signal generating unit 1022 converts the L signal and C signal at a predetermined ratio to generate an R signal that has a predetermined phase with respect to the L signal and C signal.

[0039] Specifically, as shown in Figure 5, the acoustic filter coefficient q R The phase of the convolved speech signal is determined by the acoustic filter coefficient q L The speech signal convolved with and the acoustic filter coefficients q c is in almost antiphase with the convoluted audio signal. R Ha-(q L +q C ) / 2. Therefore, the R signal generation unit 1022 mixes the L signal and the C signal at half each. This mixing can be performed, for example, in mixer 1022a. Furthermore, the R signal generation unit 1022 outputs the mixed signal with its phase shifted by 180 degrees as the R signal. This phase adjustment can be performed in phase adjuster 1022b. This phase adjustment makes the phase of the R signal approximately opposite to the phases of the L signal and the C signal.

[0040] Here, the 180-degree phase adjustment can also be achieved by simply reversing the polarity of the signal line connected to amplifier 1023R relative to the polarity of the signal line connected to amplifier 104L and the polarity of the signal line connected to amplifier 104C. In this case, R signal generating unit 1022 can be composed of only a mixer.

[0041] Also, as shown in Figure 4, the acoustic filter coefficient q R The gain of the convolved speech signal is calculated by the acoustic filter coefficient q C The speech signal convolved with and the acoustic filter q L The gain of the convoluted audio signal is lower than that of the convoluted audio signal. This gain is adjusted by amplifier 104R.

[0042] Figure 6 shows the acoustic filter coefficient q L , q C 6 is a diagram showing a comparison between the gain characteristics of the L signal and C signal convolved with the gain characteristics of the R signal generated from the L signal and C signal. In FIG. 6, the gain of the amplifier 104R is 1 / 3. FIG. 7 is a diagram showing a comparison between the gain characteristics of the L signal and C signal convolved with the gain characteristics of the R signal generated from the L signal and C signal. In FIG. 6, the gain of the amplifier 104R is 1 / 3. L , q C 6 is a diagram showing a comparison of the phase characteristics of the L signal and C signal convolved with q and the phase characteristics of the R signal generated from the L signal and C signal. As shown in FIG. 6, the amount of reduction in the gain of the R signal in the range of about 500 Hz to 3000 Hz is almost the same as the amount of reduction shown in FIG. 4. Also, as shown in FIG. 7, the phase of the R signal in the range of about 500 Hz to 3000 Hz is almost the opposite phase to the L signal and C signal. In other words, the gain and phase characteristics of the R signal generated from the L signal and C signal are different when the acoustic filter coefficient q is added to the audio signal. R The R signal may have gain and phase characteristics that are substantially the same as those of the R signal generated by convolving the R signal.

[0043] As described above, according to the embodiment, by adding two-channel audio signals input to two speakers at a predetermined ratio, a signal having a desired phase relative to these two-channel audio signals is generated. Furthermore, according to the embodiment, the gain of the audio signal added at the predetermined ratio can be adjusted by an amplifier. Therefore, in the embodiment, the amplitude and phase of sound emitted from speakers whose number is greater than the number of control channels can be controlled.

[0044] In the embodiment, an example is shown in which the volume increase control and the acoustic power control are combined. On the other hand, the L signal and the C signal input to the R signal generating unit 1022 do not necessarily have to be the same as the acoustic filter coefficient q L , q C That is, according to the technology of the embodiment, audio signals of any amplitude and phase for three speakers can be generated using a signal processing device for 2ch control.

[0045] (Variation 1) Modifications of the embodiment will be described below. In the embodiment, the signal processing device and the speaker are connected by wire. On the other hand, in the embodiment, the signal processing device and the speaker may be connected wirelessly.

[0046] Fig. 8 is a diagram showing an example of the configuration of an acoustic control device in which an audio signal processing device and speakers are wirelessly connected according to Modification 1. The acoustic control device 100 in Fig. 8 includes an audio signal input unit 101, an audio signal processing device 102a, an audio signal processing device 102b, a control device 103, amplifiers 104L, 104C, and 104R, and speakers 105L, 105C, and 105R.

[0047] The audio signal input unit 101 inputs an audio signal to the audio signal processing device 102a. The audio signal input unit 101 may also input the audio signal to the control device 103.

[0048] The audio signal processing device 102a performs signal processing on the audio signal and transmits the processed audio signal to the audio signal processing device 102b. The audio signal processing device 102a includes acoustic filters 1021L and 1021C and a wireless transmission unit 1023.

[0049] The acoustic filter 1021L filters the audio signal input from the audio signal input unit 101 using an acoustic filter coefficient q designated by the control device 103. L Then, the acoustic filter 1021L outputs the L signal obtained by filtering to the wireless transmission unit 1023. Also, the acoustic filter 1021C filters the audio signal input from the audio signal input unit 101 according to the acoustic filter coefficient q C Then, acoustic filter 1021C outputs the C signal obtained by filtering to radio transmission section 1023. Acoustic filter coefficient q L and q C is the same as that described in the embodiment.

[0050] The wireless transmitting unit 1023 is, for example, a 2-channel short-range wireless transmitter conforming to Bluetooth (registered trademark), and transmits a wireless signal including an L signal and a wireless signal including a C signal to the wireless receiving unit 1024 of the audio signal processing device 102b.

[0051] The audio signal processing device 102b receives wireless signals containing the respective audio signals from the audio signal processing device 102a, extracts the audio signals from the received wireless signals, and performs signal processing on the extracted audio signals. The audio signal processing device 102b has an R signal generation unit 1022 and a wireless receiving unit 1024.

[0052] R signal generation unit 1022 generates an R signal for speaker 105R from the L signal and C signal received by wireless receiving unit 1024. Then, R signal generation unit 1022 outputs the R signal to amplifier 104R. R signal generation unit 1022 has a configuration similar to that shown in FIG. 2, for example, and mixes the L signal and the C signal at a mixing ratio specified by control device 103. For example, R signal generation unit 1022 mixes an L signal multiplied by 2 and a C signal multiplied by 2 at a ratio of 1:1.

[0053] The wireless receiving unit 1024 is, for example, a Bluetooth-compliant 2-channel short-range wireless receiver that receives a wireless signal including an L signal and a wireless signal including a C signal. The wireless receiving unit 1024 then outputs the L signal extracted from each wireless signal to amplifier 104L and R signal generating unit 1022, and outputs the C signal to amplifier 104C and R signal generating unit 1022.

[0054] The control device 103 determines the acoustic filter coefficients q to be given to the acoustic filters 1021L and 1021C. L , q C The control device 103 is also a device for determining the gain to be given to the R signal generation unit 1022. The control device 103 may also set the gains of the amplifiers 104L, 104C, and 104R. The control device 103 may have a configuration similar to that shown in FIG.

[0055] Amplifier 104L amplifies the L signal by a gain specified by control device 103. Amplifier 104C amplifies the C signal by a gain specified by control device 103. Amplifier 104R amplifies the R signal by a gain specified by control device 103.

[0056] The speakers 105L, 105C, and 105R are wirelessly connected to the audio signal processing device 102a via the amplifiers 104L, 104C, and 104R, and are sound sources that emit sounds corresponding to the input audio signals. The speaker 105L operates as the left speaker, the speaker 105C operates as the center speaker, and the speaker 105R operates as the right speaker.

[0057] According to the above-described first modification, 2-channel audio signals input to two speakers are wirelessly transmitted, and signals input to the remaining speakers are generated from these wirelessly transmitted audio signals.

[0058] The radios used in many audio playback devices are 2-channel radios. Therefore, a separate radio is required to transmit and receive audio signals for three speakers. Wireless communication typically involves delays. The amount of delay varies from radio to radio and is unstable. Because the amount of delay is unstable, it is difficult to correct the phase delay between audio signals caused by differences in the amount of delay when different radios are used. Furthermore, Bluetooth devices require pairing, and different phase delays can occur with each pairing. Therefore, it is even more difficult to correct the phase delay between audio signals when two different Bluetooth devices are used.

[0059] In Modification 1, the audio signal processing device 102a has only one wireless transmitting unit 1023, the audio signal processing device 102b has only one wireless receiving unit 1024, and there is only one pairing of wireless devices for transmitting audio signals between the audio signal processing device 102a and the audio signal processing device 102b. In Modification 1, a separate wireless device is not required, so phase delay due to the use of different wireless devices does not occur. Therefore, the phase difference between the audio signals input to each speaker can be a desired value. Therefore, even when the speakers are connected wirelessly, processing that requires adjustment of the amplitude and phase of three speakers, such as sound field control, can be realized using a 2-channel control signal processing device.

[0060] (Variation 2) In the embodiment, an example is shown in which a 2-channel control signal processing device is used to radiate audio with desired amplitude and phase from three speakers. In contrast, the technology of the embodiment is applied to an example in which an N-channel control signal processing device is used to radiate audio with desired amplitude and phase from M-channel speakers (M is an integer greater than N).

[0061] Fig. 9 is a diagram showing an example of the configuration of an acoustic control device of Modification 2. The acoustic control device 100 in Fig. 9 has an audio signal input unit 101, an Nch controlled audio signal processing device 102, a control device 103, M amplifiers 104-1, 104-2, ..., 104-M, and M speakers 105-1, 105-2, ..., 105-M.

[0062] The audio signal input unit 101 inputs an audio signal to the audio signal processing device 102. The audio signal input unit 101 may also input the audio signal to the control device 103.

[0063] The audio signal processing device 102 performs signal processing on an audio signal. The audio signal processing device 102 has N acoustic filters 1021-1, 1021-2, ..., 1021-N, and a first signal generation unit 1022-1, a second signal generation unit 1022-2, ..., an L-th signal generation unit 1022-L (L is a natural number, and L=MN).

[0064] The acoustic filters 1021-1, 1021-2, ..., 1021-N respectively convert the audio signal input from the audio signal input unit 101 into acoustic filter coefficients q1, q2, ..., q N Then, the acoustic filters 1021-1, 1021-2, ..., 1021-N output the signals obtained by filtering to the amplifiers 104-1, 104-2, ..., 104-N.

[0065] The first signal generation unit 1022-1, the second signal generation unit 1022-2, ..., the L-th signal generation unit 1022-L generate the first signal, the second signal, ..., the L-th signal by adding the signals filtered by the acoustic filters 1021-1, 1021-2, ..., 1021-N at a predetermined ratio. For example, the i-th signal generated by the i-th signal generation unit 1022-i (1 ≤ i ≤ L) is expressed as U i Then, the i-th signal generation unit 1022-i performs signal addition as shown in the following equation (10) to generate the i-th signal U i Generate.

number

[0066] The amplifiers 104-1, 104-2, ..., 104-M respectively convert the audio signals output from the acoustic filters 1021-1, 1021-2, ..., 1021-N and the first signal generator 1022-1, the second signal generator 1022-2, ..., the L-th signal generator 1022-L into gains γ j(1≦j≦M). Amplifier 104C amplifies the C signal with a gain specified by control device 103. For example, to obtain a signal with the characteristics shown in FIGS. 6 and 7, γ j = 1 / 3. Generally, γ j is determined by approximation calculation of the gain characteristic and the phase characteristic of the acoustic filter coefficient to be applied to the audio signal to be input to the i-th speaker. Also, in Fig. 10, the amplifiers 104-1, 104-2, ..., 104-M may be connected to the audio signal processing device 102 by wire. As in the first modification, the amplifiers 104-1, 104-2, ..., 104-M may be connected to the audio signal processing device 102 by wireless.

[0067] The speakers 105-1, 105-2, . . . , 105-M are sound sources that emit sounds corresponding to audio signals input via corresponding amplifiers.

[0068] In the above-described second modification, α i1 , α i2 , …, α iN , β i , γ j By appropriately determining the values ​​of q1, q2, ..., q N A signal with an arbitrary amplitude and phase can be generated for the filtered signal.

[0069] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0070] 100 Acoustic control device, 101 Audio signal input unit, 102, 102a, 102b Audio signal processing device, 103 Control device, 104L, 104C, 104R, 104-1, 104-2, ..., 104-M Amplifier, 105L, 105C, 105R, 105-1, 105-2, ..., 105-M Speaker, 1021L, 1021C, 1021-1, 1021-2, ..., 1021-N Acoustic filter, 1022 R signal generation unit, 1022-1, 1022-2, ..., 1022-L First, second, ..., Lth signal generation unit, 1031 Acquisition unit, 1032 Acoustic filter coefficient calculation unit, 1033 Acoustic filter coefficient storage unit, 1034 Acoustic filter setting unit.

Claims

1. an N-channel acoustic filter (N is an integer equal to or greater than 2) applied to an input audio signal; L signal generators that generate L (L is a natural number) second control sound source signals having phases that have a predetermined relationship with the N first control sound source signals by adding N first control sound source signals output from the N channel acoustic filters at a predetermined ratio; M (M is N+L) sound sources that radiate sounds based on first control sound source signals output from the N-channel acoustic filters and second control sound source signals output from the L signal generators; An acoustic control device comprising:

2. 2. The acoustic control device according to claim 1, further comprising M amplifiers provided between each of the acoustic filters and the sound source and between each of the signal generating units and the sound source, and amplifying the input first control sound source signal and second control sound source signal by a predetermined gain.

3. The predetermined ratio and the predetermined gain are a first relational expression between acoustic filters applied to an audio signal containing information of sounds reproduced by each of the M sound sources, the first relational expression being based on an acoustic power control law for controlling acoustic power for the sounds reproduced by the M sound sources; a second relational expression between acoustic filters applied to an audio signal containing information of sounds reproduced by each of the M sound sources, based on a sound increase control law that increases the sound pressure at the sound increase control point by the sounds reproduced by the M sound sources; The gain and phase characteristics of the acoustic filter coefficients of the acoustic filters applied to the M sound sources are calculated based on the following equation: The acoustic control device according to claim 2 .

4. the acoustic filter is provided in a first signal processing device, and the signal generating unit is provided in a second signal processing device different from the first signal processing device; the first signal processing device further includes a wireless transmission unit that transmits a wireless signal including the first control sound source signal to the second signal processing device; the second signal processing device further includes a wireless receiving unit that receives a wireless signal including the first control sound source signal; the sound source radiates sound based on the first control sound source signal and the second control sound source signal output from the second signal processing device. The acoustic control device according to claim 1 .

5. Applying an N-channel acoustic filter (N is an integer equal to or greater than 2) to the input audio signal; generating L (L is a natural number) second control sound source signals having phases in a predetermined relationship with the N first control sound source signals by adding N first control sound source signals output from the N channel acoustic filters at a predetermined ratio; radiating sounds from M (M is N+L) sound sources based on the first control sound source signal and the L second control sound source signals; An acoustic control method comprising:

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