JP6268807B2 - Audio signal processing device - Google Patents

Description

  The present invention relates to an apparatus for reproducing an audio signal using a plurality of speakers.

  2. Description of the Related Art An audio signal processing device that forms a sound field based on a synthesized sound image with a plurality of speakers is known. For example, some audio sources, such as DVDs (Digital Versatile Discs), record multichannel audio signals such as 5.1 channels. An audio signal processing apparatus that reproduces such an audio source is becoming popular in general households. If each speaker is arranged at a recommended position in the listening room, an audio reproduction effect such as surround sound can be obtained by reproducing the audio source using the audio signal processing device. On the other hand, even if the arrangement of the speakers is at the recommended position and the balance of the volume from each speaker is adjusted at the predetermined viewing position, if the subsequent viewing position is different from the predetermined viewing position, each speaker There was a possibility that the balance of sound volume from was lost. Therefore, a technique is known in which spatial characteristics are adjusted so that the sound volume is relatively different at a plurality of spatial positions, and sound from a speaker is radiated at a different sound volume according to the viewing position (for example, Patent Documents). 1).

JP-A-8-265071

  However, in the conventional audio signal processing device, even when the sound is emitted from each speaker at a different volume according to the viewing position, if the overall volume level is lowered to a predetermined volume level, for example, −40 dB, Due to the noise of the entire room and the reflection of the room, the farther the speaker from the viewing position, the harder it is to hear the sound. In such a case, if the process of increasing the volume from a speaker at a far position is performed, the volume of the speaker will not decrease even though the overall volume level is lowered. There is a possibility that it becomes noise to the surroundings.

  The present invention has been made in view of the above-described circumstances, and achieves a desired acoustic effect with a simple configuration even when the position of the speaker deviates from an ideal position and the overall volume level is lowered. To solve it.

  In order to solve the above-described problem, an audio signal processing device according to the present invention includes a distance acquisition unit that acquires distances from a plurality of speakers to a viewing position, a volume acquisition unit that acquires the entire volume, and the volume acquisition unit. The volume acquired by the above is less than or equal to a predetermined volume, and based on the distance acquired by the distance acquisition unit, the viewing position has moved from a reference position located at a predetermined distance relative to the plurality of speakers If the determination is made, the corrected amount of the output volume of the output audio signal for the speaker far from the viewing position is calculated as the output volume and the speaker closer to the viewing position acquired by the distance acquisition unit. And a calculation unit that calculates based on the distance from the viewing position to the viewing position, and the correction amount is used as an output audio signal of a speaker closer to the viewing position. Characterized in that it comprises an addition unit for calculation for.

  According to this invention, the calculation unit is configured such that the volume acquired by the volume acquisition unit is equal to or lower than a predetermined volume, and the viewing position is predetermined for the plurality of speakers based on the distance acquired by the distance acquisition unit. When it is determined that the user has moved from the reference position at the distance position, the correction amount for the output volume of the output audio signal for the speaker far from the viewing position is calculated as the output volume and the distance acquisition unit. Is calculated based on the distance from the speaker on the side closer to the viewing position acquired by the above to the viewing position, so that the overall volume is equal to or lower than a predetermined volume, and the viewing position is moved far from the reference position Even when the signal from the speaker on the side becomes difficult to hear at the viewing position, an appropriate volume of the signal output as the correction amount is calculated. In addition, since the addition unit adds the correction amount calculated in this way to the output audio signal of the output target speaker, at the viewing position without increasing the output volume of the speaker that is equal to or greater than the predetermined distance. The signal that should have been output from the far-side speaker can be reached at the original volume. Therefore, even when the overall volume is equal to or lower than the predetermined volume and the viewing position is moved from the reference position, it is possible to maintain a sense of overall spread at the viewing position.

In the audio signal processing system described above, the distance acquisition unit acquires distances from the plurality of speakers to the viewing position based on the coordinates of the plurality of speakers and the coordinates of the viewing position. May be.
According to the present invention, each distance is acquired based on the coordinates. Therefore, even when the overall volume is equal to or lower than the predetermined volume and the viewing position is moved from the reference position, the viewing position is According to the distance from the speaker close to the viewing position to the viewing position, the volume of the output signal of the speaker far from the viewing position can be appropriately corrected and output from the near speaker. Therefore, even when the overall volume is equal to or lower than the predetermined volume and the viewing position is moved from the reference position, it is possible to maintain a sense of overall spread at the viewing position.

The above-described audio signal processing system may include a delay unit that delays the audio signal for a predetermined time, and the addition unit may add the correction amount delayed by the delay unit for a predetermined time to the output audio signal. Good.
According to the present invention, the audio signal for the correction is output from a speaker different from the speaker to be originally output, but is output after being delayed by a predetermined time by the delay unit. When the same sound is heard from a plurality of sound source directions, there is a phenomenon that the localization is biased toward the sound source direction of the sound that has arrived earliest. This phenomenon is generally called the Haas effect, and in the present invention, the audio signal for correction is delayed for a predetermined time by the delay unit. You can make it feel like it was done.

1 is a block diagram illustrating a configuration example of an audio signal processing system 1A according to an embodiment of the present invention. It is a top view which shows arrangement | positioning of speaker SP1-SP5 in the listening room which concerns on embodiment of this invention. It is a block diagram which shows an example of the hardware constitutions of the audio signal processing apparatus 20 which concerns on embodiment of this invention. It is explanatory drawing which shows the data structure of table TBL1 memorize | stored in the memory 230 which concerns on embodiment of this invention. It is a figure which shows the relationship between the volume level of the whole, the volume level in a viewing position, and the volume level of the noise of the whole room. It is a figure which shows the positional relationship between speaker SP1-SP4 and viewing-and-listening position Plp, and the distance from each speaker to viewing-and-listening position Plp. It is a figure which shows the positional relationship between speaker SP1-SP4 and viewing-and-listening position Plp, and the distance from each speaker to viewing-and-listening position Plp. It is a figure which shows the positional relationship between speaker SP1-SP4 and viewing-and-listening position Plp, and the distance from each speaker to viewing-and-listening position Plp. It is a figure which shows the positional relationship between speaker SP1-SP4 and viewing-and-listening position Plp, and the distance from each speaker to viewing-and-listening position Plp. It is a figure which shows the positional relationship between speaker SP1-SP4 and viewing-and-listening position Plp, and the distance from each speaker to viewing-and-listening position Plp. It is a figure which shows the positional relationship between speaker SP1-SP4 and viewing-and-listening position Plp, and the distance from each speaker to viewing-and-listening position Plp. It is a figure which shows the positional relationship between speaker SP1-SP4 and viewing-and-listening position Plp, and the distance from each speaker to viewing-and-listening position Plp. It is a figure which shows the positional relationship between speaker SP1-SP4 and viewing-and-listening position Plp, and the distance from each speaker to viewing-and-listening position Plp. It is a flowchart which shows the content of the signal correction process in the audio signal processing apparatus which concerns on embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
<1: Configuration of audio signal processing system>
FIG. 1 shows a configuration example of an audio signal processing system according to the first embodiment. The audio signal processing system 1A includes a terminal device 10 such as a smartphone, an audio signal processing device 20, and speakers SP1 to SP5. The terminal device 10 is a communication device such as a smartphone and can communicate with the audio signal processing device 20. The form of communication may be either wireless or wired, but for example, communication is possible via a wireless LAN (Local Area Network). Further, the terminal device 10 can download an application program from a predetermined site on the Internet. Such application programs include, for example, a program used to measure the distance between the plurality of speakers SP1 to SP5 and the viewing position.

  The audio signal processing device 20 is a so-called multichannel amplifier. The audio signal processing device 20 generates output audio signals OUT1 to OUT5 obtained by adding sound effects to the input audio signals IN1 to IN5, and supplies OUT1 to OUT5 to the speakers SP1 to SP5. The speakers SP1 to SP5 are connected to the audio signal processing device 20 by wire or wirelessly.

  FIG. 2 shows an arrangement example of the speakers SP1 to SP5 in the listening room of the audio signal processing system 1A. In this example, five speakers SP1 to SP5 are arranged in the listening room, but the number of speakers is not limited to five, and may be four or less, or may be six or more. . For example, a so-called 5.1 surround system may be obtained by adding a subwoofer speaker.

  The user B views the sound emitted from the speakers SP1 to SP5 at a predetermined position (hereinafter referred to as “reference position Pref”). In this example, the speaker SP5 is disposed in front of the user B, the speaker SP1 is disposed in front of the user B diagonally left, the speaker SP2 is disposed in front of the user B diagonally right, and the speaker SP3 is disposed in the user B. The speaker SP4 is arranged diagonally to the left of the user B. The user B can hear the user B as if the sound source is at a specific position by simultaneously listening to the sounds emitted from the speakers SP1 to SP5.

  The audio signal processing device 20 generates and outputs output audio signals OUT1 to OUT5 that sound as if sound is being emitted from a desired position based on the positions where the plurality of speakers SP1 to SP5 are arranged. Each position of the plurality of speakers SP1 to SP5 is measured in advance.

  In FIG. 3, the audio signal processing device 20 includes a control unit 210 that functions as a control center of the entire device, a communication interface 220 that performs communication with the outside, and a memory 230 that stores programs and data and functions as a work area of the control unit 210. And an external interface 240 that inputs a signal from an external device such as a microphone and supplies the signal to the controller 210, and a processing unit 250. The processing unit 250 and the control unit 210 output the output audio signals OUT1 to OUT4 obtained by performing correction processing, which will be described later, to the input audio signals IN1 to IN4 based on the positions of the speakers SP1 to SP4. Generate for each. In this embodiment, the input audio signal IN5 for the speaker SP5 is not subjected to correction processing described later, and is supplied to the speaker SP5 as the output audio signal OUT5. The processing unit 250 and the control unit 210 are functional blocks that are realized when the CPU executes a program. The processing unit 250 and the control unit 210 include a distance acquisition unit that acquires distances from the plurality of speakers SP1, SP2, SP3, and SP4 to a predetermined viewing position, a volume acquisition unit that acquires the entire volume, and a volume acquisition unit. When the acquired volume is less than or equal to a predetermined volume and the predetermined viewing position is moved from a reference position at a predetermined distance with respect to the plurality of speakers, the far side from the predetermined viewing position The correction amount for the output volume of the output audio signal for the speaker is set to the output volume and the distance from the speaker closer to the predetermined viewing position acquired by the distance acquisition unit to the predetermined viewing position. It functions as a calculation unit that calculates based on and an addition unit that adds the correction amount to the output audio signal of the output target speaker.

  The processing unit 250 includes adders 331 to 334, coefficient units 400 to 411, and delay units 500 to 511. The control unit 210 appropriately selects and drives any one of the coefficient units 400 to 411 and the delay units 500 to 511 according to the viewing position and the overall volume. Specific examples of selecting the coefficient units 400 to 411 and the delay units 500 to 511 will be described later.

  The coefficient unit 400 outputs an audio signal A1 obtained by multiplying the input audio signal IN4 for the speaker SP4 by the coefficient K41 to the delay unit 500. The coefficient unit 401 outputs an audio signal A2 obtained by multiplying the input audio signal IN3 for the speaker SP3 by a coefficient K31 to the delay unit 501. The coefficient unit 402 outputs an audio signal A3 obtained by multiplying the input audio signal IN2 for the speaker SP2 by the coefficient K21 to the delay unit 502.

  The coefficient unit 403 outputs an audio signal A4 obtained by multiplying the input audio signal IN1 for the speaker SP1 by the coefficient K12 to the delay unit 503. The coefficient unit 404 outputs an audio signal A5 obtained by multiplying the input audio signal IN3 for the speaker SP3 by the coefficient K32 to the delay unit 504. The coefficient unit 405 outputs an audio signal A6 obtained by multiplying the input audio signal IN4 for the speaker SP4 by the coefficient K42 to the delay unit 505.

  The coefficient unit 406 outputs the audio signal A7 obtained by multiplying the input audio signal IN2 for the speaker SP2 by the coefficient K23 to the delay unit 506. The coefficient unit 407 outputs an audio signal A8 obtained by multiplying the input audio signal IN1 for the speaker SP1 by the coefficient K13 to the delay unit 507. The coefficient unit 408 outputs an audio signal A9 obtained by multiplying the input audio signal IN4 for the speaker SP4 by the coefficient K43 to the delay unit 508.

  The coefficient unit 409 outputs an audio signal A10 obtained by multiplying the input audio signal IN1 for the speaker SP1 by the coefficient K14 to the delay unit 509. The coefficient unit 410 outputs the audio signal A11 obtained by multiplying the input audio signal IN2 for the speaker SP2 by the coefficient K24 to the delay unit 510. The coefficient unit 411 outputs an audio signal A12 obtained by multiplying the input audio signal IN3 for the speaker SP3 by the coefficient K34 to the delay unit 511.

  The delay units 500 to 511 delay the audio signals A1 to A12 output from the coefficient units 400 to 411 for a predetermined time in order to obtain a hearth effect, and output the delayed signals to the addition units 331 to 334. Details of the Hearth effect will be described later.

  Adders 331 to 334 add input audio signals IN1 to IN4 for speakers SP1 to SP4 and audio signals A1 to A12 output from delay units 500 to 511, and output audio signals OUT1 to OUT4.

  The memory 230 stores in advance a table TBL1 shown in FIG. The table TBL1 is a table in which data representing the relationship between the viewing position and the coefficient part to be selected is stored. The memory 230 stores in advance mathematical formulas for calculating the coefficients K12, K13, K14, K21, K23, K24, K31, K32, K34, K41, K42, and K43 of each coefficient part. Details of the formula will be described later.

<2: Operation of the audio signal processing system>
Next, the operation of the audio signal processing system will be described by dividing the calculation of the coefficient in the coefficient section, the signal processing using the coefficient section and the adding section, and the hearth effect process.
<2-1: Calculation of coefficient in coefficient part>
As an example, a case where the listening room 30 is square as shown in FIG. 6 will be described. The speaker SP1, the speaker SP2, the speaker SP3, and the speaker SP4 are assumed to be disposed at the four corners of the listening room 30. A straight line passing through the midpoint between the speakers SP1 and SP4, the center point of the listening room 30, and the midpoint between the speakers SP2 and SP3 is an axis that passes through the center point of the listening room 30 and is orthogonal to the X axis. Is the Y axis. The direction from the midpoint between the speakers SP1 and SP4 to the midpoint between the speakers SP2 and SP3 is the positive direction of the X axis, and the midpoint between the speakers SP1 and SP2 from the midpoint between the speakers SP4 and SP3. The direction toward the point is the positive direction of the Y axis.

First, consider a case where the viewing position Plp is closest to SP2 shown in FIG. In this case, the distance from the speakers SP1 to listening position Plp _{x 1,} the distance from the speaker SP2 to listening position Plp _{x 2,} the distance from the speaker SP3 to listening position Plp _{x 3,} and to the viewing position Plp from the speaker SP4 the distance between the _{x 4.}

  When the viewing position is at the reference position Pref, that is, at the origin of the XY coordinates shown in FIG. 6, the distance from each speaker to the viewing position is equal, so if a signal with the same volume is output from each speaker, At the viewing position, the signal from any speaker can be heard at the same volume.

  However, as shown in FIG. 6, when the viewing position Plp is closest to SP2, the distance from each speaker to the viewing position Plp is different. Therefore, if a signal with the same volume is output from each speaker, the viewing position Plp The volume balance of signals from each speaker will be lost. For example, if the output volume vo3 of the signal of the speaker SP3 is 0 db (1.0) and the distance d3 from the speaker SP3 to the reference position Pref is 1 m, the volume is inversely proportional to the square of the distance, so the volume at the reference position Pref vr3 is as follows.

(Equation 1)
vr3 = vo3 / d3 ² = 1.0 / 1 = 1.0

On the other hand, 0db (1.0) the output volume vo3 signal of the speaker SP3, and the distance _{x 3} of the speaker SP3 to viewing position Plp and 1.2 m, volume vp3 at viewing position Plp is as follows.

(Equation 2)
vp3 = vo3 / x ₃ ² = 1.0 / 1.44 = 0.69

  That is, the volume of the signal of the speaker SP3 at the viewing position Plp is reduced to -3.2 db (0.69). Therefore, at the viewing position Plp, the volume of the signal of the speaker SP3 is insufficient by −10.2 db (0.31).

Therefore, in the present embodiment, the output volume vo3 of the signal of the speaker SP3 is adjusted so as to compensate for the insufficient volume signal. That is, when the distance _{x 3} of the speaker SP3 to listening position Plp is 1.2 m, because the volume vp3 at viewing position Plp the 0db (1.0), the following output volume vo3 signal of the speaker SP3 Adjust as follows.

(Equation 3)
vo3 = vp3 * x ₃ ² = 1.0 * 1.44 = 1.44

The output volume vo3 signal of the speaker SP3, by adjusting the 3.2 dB (1.44), the volume vp3 at viewing position Plp when the distance _{x 3} is 1.2m becomes 0db (1.0) . In the present embodiment, the output volume of other speakers is adjusted in the same manner, and even when the viewing position Plp moves from the reference position Pref, the output volume difference between the speakers is prevented.

  However, even when the output volume of each speaker is performed in this way, if the overall volume level is lowered to around -40 dB, the signal from the speaker SP3 is buried in the noise of the entire room as shown in FIG. Or may be difficult to hear due to reflections in the room. This phenomenon becomes more pronounced as the speaker is farther away from the speaker.

  Therefore, in the present embodiment, as described above, when the distance from each speaker to the viewing position Plp is different, that is, when the viewing position Plp is moved from the reference position Pref, the overall volume level is predetermined. When it becomes lower than the level (for example, −40 dB), it is considered that there is insufficient output due to distance attenuation from the speaker whose distance from the viewing position Plp is longer than the distance from the reference position Pref. Correction for outputting from a speaker near the position Plp is performed. In the above example, when the overall volume level is lower than a predetermined level (for example, −40 dB), the shortage in the viewing position Plp of the output signals from the speakers SP1, SP4, and SP3 at that time is viewed. The output is made from the speaker SP2 close to the position Plp. This increases the output signals from the speakers SP1, SP4, and SP3 far from the viewing position Plp so as to compensate for the output signal that becomes difficult to hear when the overall volume level becomes lower than a predetermined level (for example, −40 dB). This is because the sound volume from the speakers SP1, SP4, and SP3 cannot be lowered even though the overall sound volume is lowered, and there is a possibility that noise may be generated to the surroundings.

  When the shortage in the viewing position Plp of the output volume vo3 from the speaker SP3 when the overall volume level is lower than a predetermined level (eg, −40 dB) is output from the speaker SP2 closest to the viewing position. Is as follows. In this example, the output volume of the speaker SP3 signal output from the speaker SP2 is vo2_3.

First, the shortage of the output volume vo3 from the speaker SP3 at the viewing position Plp is as follows.
(Equation 4)
Shortfall ^{_{= vo3- (vo3 / x 3 2}} ) = [1- (1 / x 3 2)] * vo3
In order to compensate for this shortage by outputting from the speaker SP2, the output volume vo2_3 of the signal for the speaker SP3 output from the speaker SP2 is as follows.
(Equation 5) vo2_3 = [1- (1 / x ₃ ² )] * vo ₃ * x ₂ ²
However, when x ₃ is less than 1.0, since not obtained the correct value in the equation shown in equation (5) is normalized distance in x _2.
(Equation 6)
_{vo2_3 = [1- (1 / (} x 3 / x 2) 2)] * vo3 * (x 2 / x 2) 2
= [1- (1 / (x ₃ / x ₂ ) ² )] * vo3
Here, when [1- (1 / x ₃ ² )] or [1- (1 / (x ₃ / x ₂ ) ² )] is expressed as a coefficient K32, the volume of the signal for the speaker SP3 output from the speaker SP2 vo2_3 can be expressed as follows.

(Equation 7)
vo2_3 = K32 * vo3
K32 = [1- (1 / x ₃ ² )] * x ₂ ² or [1- (1 / (x ₃ / x ₂ ) ² )]

In the example shown in FIG. 6, the distance x ₁ from the speakers SP1 to listening position Plp also is longer than the distance from the speakers SP1 to the reference position Pref, as in the case of the speaker SP3, the overall volume level When it becomes lower than a predetermined level (for example, −40 dB), it becomes difficult to hear a signal from the speaker SP1. Therefore, in the present embodiment, the signal from the speaker SP1 is also configured to be output from the speaker SP2 by multiplying the output volume vo1 of the signal for the speaker SP1 by the coefficient K12 as in the case of the speaker SP3. The signal vo2_1 for the speaker SP1 output from the speaker SP2 is obtained as follows.

First, the shortage of the output volume vo1 from the speaker SP1 at the viewing position Plp is as follows.
(Equation 8)
Shortfall ^{_{= vo1- (vo1 / x 1 2}} ) = [1- (1 / x 1 2)] * vo1
In order to compensate for this shortage by outputting from the speaker SP2, the output volume vo2_1 of the signal for the speaker SP1 output from the speaker SP2 is as follows. (Equation 9)
vo2_1 = [1- (1 / x ₁ ² )] * vo 3 * x ₁ ²
However, if x ₁ is less than 1.0, since not obtained the correct value in the equation shown in equation (9), normalized distance in x _2.
(Equation 10)
_{vo2_1 = [1- (1 / (} x 1 / x 2) 2)] * vo3 * (x 2 / x 2) 2
_{= [1- (1 / (x} 1 / x 2) 2)] * vo3
Here, when [1- (1 / x ₁ ² )] or [1- (1 / (x ₁ / x ₂ ) ² )] is expressed as a coefficient K12, the volume of the signal for the speaker SP1 output from the speaker SP2 vo2_1 can be expressed as follows.
(Equation 11)
vo2_1 = K12 * vo1
K12 = [1- (1 / x ₁ ² )] * x ₂ ² or [1- (1 / (x ₁ / x ₂ ) ² )]

In the example shown in FIG. 6, the distance x ₄ from the speaker SP4 to listening position Plp also is longer than the distance from the speaker SP4 to the reference position Pref, as in the case of the speaker SP3, the overall volume level When it becomes lower than a predetermined level (for example, −40 dB), it becomes difficult to hear a signal from the speaker SP4. Therefore, in the present embodiment, the signal from the speaker SP4 is also configured to be output from the speaker SP2 by multiplying the output volume vo4 of the signal for the speaker SP4 by the coefficient K42 as in the case of the speaker SP3. The signal vo2_4 for the speaker SP4 output from the speaker SP2 is obtained as follows.
First, the shortage of the output volume vo4 from the speaker SP4 at the viewing position Plp is as follows.
(Equation 12)
Shortfall ^{_{= vo4- (vo4 / x 4 2}} ) = [1- (1 / x 4 2)] * vo4
In order to compensate for this shortage by outputting from the speaker SP2, the output volume vo2_4 of the signal for the speaker SP4 output from the speaker SP2 is as follows.
(Equation 13)
vo2_4 = [1- (1 / x ₄ ² )] * vo ₄ * x ₄ ²
However, if x ₄ is less than 1.0, since not obtained the correct value in the equation shown in equation (13), it normalizes distance in x _2.
(Equation 14)
_{vo2_4 = [1- (1 / (} x 4 / x 2) 2)] * vo4 * (x 4 / x 2) 2
= [1- (1 / (x ₄ / x ₂ ) ² )] * vo4
Here, when [1- (1 / x ₄ ² )] or [1- (1 / (x ₄ / x ₂ ) ² )] is expressed as a coefficient K42, the volume of the signal for the speaker SP4 output from the speaker SP2 vo2_4 can be expressed as follows.

(Equation 15)
vo2_4 = K42 * vo4
K42 = [1- (1 / x ₄ ² )] * x ₂ ² or [1- (1 / (x ₄ / x ₂ ) ² )]

<2-2: Signal correction processing>
As described above, in the present embodiment, when the overall volume level is lower than a predetermined level (for example, −40 dB) and the distance from each speaker to the viewing position Plp is different, that is, the viewing position Plp is the reference. When the position is moved from the position Pref, the output signal of each speaker whose distance to the viewing position Plp is longer than the distance from the reference position Pref is output from the speaker closest to the viewing position Plp. Configured. This process will be described based on the circuit diagram of FIG. 3 and the flowchart of FIG. In the following description, FIGS. 4 and 6 to 13 are also referred to as appropriate.

<2-2-1: When SP2 is closest>
The control unit 210 shown in FIG. 3 first determines whether or not the overall volume level has been changed (FIG. 14: step S1). This determination is made every predetermined time or every time it is detected that the level has been changed. As a result of the determination, if the overall volume level has not been changed (FIG. 14: step S1; NO), the process is terminated. However, if the overall volume level is changed as a result of the determination (FIG. 14: step S1; YES), the control unit 210 determines whether the overall volume level is equal to or lower than a predetermined level (FIG. 14: step). S2). As a result of the determination, if the overall volume level exceeds a predetermined level (FIG. 14: step S2; NO), the process is terminated.

  However, as a result of the determination, if the overall volume level is equal to or lower than the predetermined level (FIG. 14: Step S2; YES), the control unit 210 acquires the distance from each speaker to the viewing position Plp by a known method. (FIG. 14: Step S3). In the present embodiment, the control unit 210 measures the distance between each speaker and the viewing position Plp, and determines whether or not the viewing position Plp has moved from the reference position (FIG. 14: step S4). When the viewing position Plp has not moved from the reference position as a result of the determination (FIG. 14: Step S4; NO), the control unit 210 ends the process.

  When the control unit 210 determines that the viewing position Plp has moved from the reference position (FIG. 14: Step S4; YES), the controller 210 calculates the distance from each speaker to the viewing position Plp, and is the most similar to the viewing position Plp. Identify speakers that are in close proximity. In the case of the example illustrated in FIG. 6, the control unit 210 determines that the speaker SP2 is the speaker closest to the viewing position Plp, and refers to the table TBL1 stored in the memory 230 to determine the coefficient unit to be selected. To do. In the table TBL1 shown in FIG. 4, coefficient units 403, 404, and 405 are selected when the speaker SP2 is closest to the viewing position Plp.

  The coefficient used in the coefficient unit 403 is K12, the coefficient used in the coefficient unit 404 is K32, and the coefficient used in the coefficient unit 405 is K42. Formulas for calculating these coefficients are stored in the memory 230 in advance. Yes.

(Equation 16)
K12 = [1- (1 / x ₁ ² )] * x ₂ ²
K32 = [1- (1 / x ₃ ² )] * x ₂ ²
K42 = [1- (1 / x ₄ ² )] * x ₂ ²
_However, if _{x 1,} x _3, x ₄ is 1.0 or less,
_{K12 = [1- (1 / (} x 1 / x 2) 2)]
K32 = [1- (1 / (x ₃ / x ₂ ) ² )]
K42 = [1- (1 / (x ₄ / x ₂ ) ² )]
It becomes.

  The control unit 210 calculates these coefficients by the above formulas (FIG. 14: step S5), and selects the coefficient units 403, 404, and 405 (FIG. 14: step S6). As illustrated in FIG. 3, the delay unit 503 corresponds to the coefficient unit 403, the delay unit 504 corresponds to the coefficient unit 404, and the delay unit 505 corresponds to the coefficient unit 405. An addition unit 332 corresponds to the addition unit. Therefore, the control unit 210 selects the delay unit 503, the delay unit 504, the delay unit 505, and the addition unit 332 (FIG. 14: step S6).

  Next, the control unit 210 passes the coefficients K12, K32, and K42 calculated as described above to the coefficient units 403, 404, and 405, respectively. In the coefficient units 403, 404, and 405, the coefficient K12, Coefficient part processing for multiplying K32 and K42 and outputting the correction signal to the delay part is performed (FIG. 14: step S7). Specifically, the coefficient unit 403 outputs a correction signal obtained by multiplying the input audio signal IN1 to the speaker SP1 by the coefficient K12 to the delay unit 503. The coefficient unit 404 outputs a correction signal obtained by multiplying the input audio signal IN3 to the speaker SP3 by the coefficient K32 to the delay unit 504. The coefficient unit 405 outputs a correction signal obtained by multiplying the input audio signal IN4 to the speaker SP4 by the coefficient K42 to the delay unit 505.

  The delay units 503, 504, and 505 delay the correction signals output from the coefficient units 403, 404, and 405 for a predetermined time, and perform delay unit processing that outputs them to the adder 332 (FIG. 14: step S8). Specifically, the delay unit 503 delays the correction signal obtained by multiplying the input audio signal IN1 to the speaker SP1 by the coefficient K12 for a predetermined time, and outputs the delayed signal as the audio signal A4 to the adding unit 332. The delay unit 504 delays the correction signal obtained by multiplying the input audio signal IN3 to the speaker SP3 by the coefficient K32 for a predetermined time, and outputs the delayed signal as the audio signal A5 to the adding unit 332. The delay unit 505 delays the correction signal obtained by multiplying the input audio signal IN4 to the speaker SP4 by the coefficient K42 for a predetermined time, and outputs the delayed signal as the audio signal A6 to the adding unit 332.

  The adder 332 performs an adder process that adds the audio signals A4, A5, and A6 described above to the audio signal IN2 input to the speaker SP2 (FIG. 14: step S9), and as an output audio signal OUT2 supplied to the speaker SP2. Output.

<2-2-2: When SP1 is closest>
The processing from step S1 to step S4 is the same as that when the viewing position Plp is closest to SP2, and the description thereof is omitted. When it is determined in step S4 that the viewing position Plp has moved from the reference position (FIG. 14: step S4; YES), the control unit 210 calculates the distance from each speaker to the viewing position Plp, The speaker closest to the position Plp is specified. When the controller 210 determines that the speaker SP1 is the speaker closest to the viewing position Plp as shown in FIG. 7, the controller 210 refers to the table TBL1 stored in the memory 230 and selects the speaker SP1. The coefficient part to be determined is determined. In the table TBL1 shown in FIG. 4, the coefficient units 400, 401, and 402 are selected when the speaker SP1 is the speaker closest to the viewing position Plp.

  The coefficient used in the coefficient part 400 is K41, the coefficient used in the coefficient part 401 is K31, and the coefficient used in the coefficient part 402 is K21. Formulas for calculating these coefficients are stored in the memory 230 in advance. Yes.

(Equation 17)
K41 = [1- (1 / x ₄ ² )] * x ₁ ²
K31 = [1- (1 / x ₃ ² )] * x ₁ ²
K21 = [1- (1 / x ₂ ² )] * x ₁ ²
However, when x ₄ , x ₃ and x ₂ are 1.0 or less,
_{K41 = [1- (1 / (} x 4 / x 1) 2)]
_{K31 = [1- (1 / (} x 3 / x 1) 2)]
_{K21 = [1- (1 / (} x 2 / x 1) 2)]
It becomes.

  The control unit 210 calculates these coefficients by the above formulas (FIG. 14: step S5), and selects the coefficient units 400, 401, and 402 (FIG. 14: step S6). As illustrated in FIG. 3, the delay unit 500 corresponds to the coefficient unit 400, the delay unit 501 corresponds to the coefficient unit 401, and the delay unit 502 corresponds to the coefficient unit 402. An addition unit 331 corresponds to the addition unit. Therefore, the control unit 210 selects the delay unit 500, the delay unit 501, the delay unit 502, and the addition unit 331 (FIG. 13: step S6).

  Next, the control unit 210 passes the coefficients K41, K31, and K21 calculated as described above to the coefficient units 400, 401, and 402, respectively. In the coefficient units 400, 401, and 402, the coefficient K41, Coefficient part processing for multiplying K31 and K21 and outputting the correction signal to the delay part is performed (FIG. 14: step S7). Specifically, the coefficient unit 400 outputs a correction signal obtained by multiplying the input audio signal IN4 to the speaker SP4 by the coefficient K41 to the delay unit 500. The coefficient unit 401 outputs a correction signal obtained by multiplying the input audio signal IN3 to the speaker SP3 by the coefficient K31 to the delay unit 501. The coefficient unit 402 outputs a correction signal obtained by multiplying the input audio signal IN2 to the speaker SP2 by the coefficient K21 to the delay unit 502.

  The delay units 500, 501, and 502 perform a delay unit process of delaying the correction signals output from the coefficient units 400, 401, and 402 for a predetermined time and outputting them to the adder 331 (FIG. 14: step S8). Specifically, the delay unit 500 delays the correction signal obtained by multiplying the input audio signal IN4 to the speaker SP4 by the coefficient K41 for a predetermined time, and outputs the delayed signal as the audio signal A1 to the adding unit 331. The delay unit 501 delays a correction signal obtained by multiplying the input audio signal IN3 to the speaker SP3 by a coefficient K31 for a predetermined time, and outputs the delayed signal as an audio signal A2 to the adder 331. The delay unit 502 delays the correction signal obtained by multiplying the input audio signal IN2 to the speaker SP2 by the coefficient K21 for a predetermined time, and outputs the delayed signal as the audio signal A3 to the adding unit 331.

  The adder 331 performs an adder process for adding the above-described audio signals A1, A2, and A3 to the audio signal IN1 input to the speaker SP1 (FIG. 14: step S9), and as an output audio signal OUT1 supplied to the speaker SP1. Output.

<2-2-3: When SP4 is closest>
The processing from step S1 to step S4 is the same as that when the viewing position Plp is closest to SP2, and the description thereof is omitted. When it is determined in step S4 that the viewing position Plp has moved from the reference position (FIG. 14: step S4; YES), the control unit 210 calculates the distance from each speaker to the viewing position Plp, The speaker closest to the position Plp is specified. When the controller 210 determines that the speaker SP4 is the speaker closest to the viewing position Plp as shown in FIG. 8, the controller 210 refers to the table TBL1 stored in the memory 230 and selects it. Determine the coefficient unit. In the table TBL1 shown in FIG. 4, coefficient units 409, 410, and 411 are selected when the speaker SP4 is the speaker closest to the viewing position Plp.

  The coefficient used in the coefficient unit 409 is K14, the coefficient used in the coefficient unit 410 is K24, and the coefficient used in the coefficient unit 411 is K34. Formulas for calculating these coefficients are stored in the memory 230 in advance. Yes.

(Equation 18)
K14 = [1- (1 / x ₁ ² )] * x ₄ ²
K24 = [1- (1 / x ₂ ² )] * x ₄ ²
K34 = [1- (1 / x ₃ ² )] * x ₄ ²
_However, if x _1, x 2, _{x 3} is 1.0 or less,
_{K14 = [1- (1 / (} x 1 / x 4) 2)]
_{K24 = [1- (1 / (} x 2 / x 4) 2)]
K34 = [1- (1 / (x ₃ / x ₄ ) ² )]
It becomes.

  The control unit 210 calculates these coefficients by the above formulas (FIG. 14: step S5), and selects the coefficient units 409, 410, and 411 (FIG. 14: step S6). As illustrated in FIG. 3, the delay unit 509 corresponds to the coefficient unit 409, the delay unit 510 corresponds to the coefficient unit 410, and the delay unit 511 corresponds to the coefficient unit 411. An addition unit 334 corresponds to the addition unit. Therefore, the control unit 210 selects the delay unit 509, the delay unit 510, the delay unit 511, and the addition unit 334 (FIG. 14: step S6).

  Next, the control unit 210 passes the coefficients K14, K24, and K34 calculated as described above to the coefficient units 409, 410, and 411, and the coefficient units 409, 410, and 411 receive the coefficients K14, Coefficient part processing for multiplying K24 and K34 and outputting the correction signal to the delay part is performed (FIG. 14: step S7). Specifically, the coefficient unit 409 outputs a correction signal obtained by multiplying the input audio signal IN1 to the speaker SP1 by the coefficient K14 to the delay unit 509. The coefficient unit 410 outputs a correction signal obtained by multiplying the input audio signal IN2 to the speaker SP2 by the coefficient K24 to the delay unit 510. The coefficient unit 411 outputs a correction signal obtained by multiplying the input audio signal IN3 to the speaker SP3 by the coefficient K34 to the delay unit 511.

  The delay units 509, 510, and 511 perform a delay unit process that delays the correction signal output from the coefficient units 409, 410, and 411 for a predetermined time and outputs the correction signal to the addition unit 334 (FIG. 14: step S7). Specifically, the delay unit 509 delays the correction signal obtained by multiplying the input audio signal IN1 to the speaker SP1 by the coefficient K14 for a predetermined time, and outputs the delayed signal as the audio signal A10 to the adding unit 334. The delay unit 510 delays the correction signal obtained by multiplying the input audio signal IN2 to the speaker SP2 by the coefficient K24 for a predetermined time, and outputs the delayed signal as the audio signal A11 to the adding unit 334. The delay unit 511 delays the correction signal obtained by multiplying the input audio signal IN3 to the speaker SP3 by the coefficient K34 for a predetermined time, and outputs the delayed signal as the audio signal A12 to the adding unit 334.

  The adder 334 performs an adder process that adds the audio signals A10, A11, and A12 described above to the audio signal IN4 input to the speaker SP4 (FIG. 14: step S9), and outputs the audio signal OUT4 supplied to the speaker SP4. Output.

<2-2-4: When SP3 is closest>
The processing from step S1 to step S4 is the same as that when the viewing position Plp is closest to SP2, and the description thereof is omitted. When it is determined in step S4 that the viewing position Plp has moved from the reference position (FIG. 14: step S4; YES), the control unit 210 calculates the distance from each speaker to the viewing position Plp, The speaker closest to the position Plp is specified. When the controller 210 determines that the speaker SP3 is the speaker closest to the viewing position Plp as shown in FIG. 9, the controller 210 refers to the table TBL1 stored in the memory 230 and selects it. The coefficient part is determined. In the table TBL1 shown in FIG. 4, coefficient units 406, 407, and 408 are selected when the speaker SP3 is the speaker closest to the viewing position Plp.

  The coefficient used in the coefficient unit 406 is K23, the coefficient used in the coefficient unit 407 is K13, and the coefficient used in the coefficient unit 408 is K43. Formulas for calculating these coefficients are stored in the memory 230 in advance. Yes.

(Equation 19)
K23 = [1- (1 / x ₂ ² )] * x ₃ ²
K13 = [1- (1 / x ₁ ² )] * x ₃ ²
K43 = [1- (1 / x ₄ ² )] * x ₃ ²
However, when x ₂ , x ₁ , x ₄ is 1.0 or less,
_{K23 = [1- (1 / (} x 2 / x 3) 2)]
_{K13 = [1- (1 / (} x 1 / x 3) 2)]
_{K43 = [1- (1 / (} x 4 / x 3) 2)]
It becomes.

  The control unit 210 calculates these coefficients by the above formulas (FIG. 14: step S5), and selects the coefficient units 406, 407, and 408 (FIG. 14: step S6). As illustrated in FIG. 3, the delay unit 506 corresponds to the coefficient unit 406, the delay unit 507 corresponds to the coefficient unit 407, and the delay unit 508 corresponds to the coefficient unit 408. An adder 333 corresponds to the adder. Therefore, the control unit 210 selects the delay unit 506, the delay unit 507, the delay unit 508, and the addition unit 333 (FIG. 14: step S6).

  Next, the control unit 210 passes the coefficients K23, K13, and K43 calculated as described above to the coefficient units 406, 407, and 408, respectively. The coefficient units 406, 407, and 408 receive the coefficient K23, Coefficient part processing for multiplying K13 and K43 and outputting the correction signal to the delay part is performed (FIG. 14: step S7). Specifically, the coefficient unit 406 outputs a correction signal obtained by multiplying the input audio signal IN2 to the speaker SP2 by the coefficient K23 to the delay unit 506. The coefficient unit 407 outputs a correction signal obtained by multiplying the input audio signal IN1 to the speaker SP1 by the coefficient K13 to the delay unit 507. The coefficient unit 408 outputs a correction signal obtained by multiplying the input audio signal IN4 to the speaker SP4 by the coefficient K43 to the delay unit 508.

  The delay units 506, 507, and 508 perform a delay unit process that delays the correction signals output from the coefficient units 406, 407, and 408 for a predetermined time and outputs them to the adder 333 (FIG. 14: Step S8). Specifically, the delay unit 506 delays the correction signal obtained by multiplying the input audio signal IN2 to the speaker SP2 by the coefficient K23 for a predetermined time, and outputs the delayed signal as the audio signal A7 to the adding unit 333. The delay unit 507 delays the correction signal obtained by multiplying the input audio signal IN1 to the speaker SP1 by the coefficient K13 for a predetermined time, and outputs the delayed signal as the audio signal A8 to the adding unit 333. The delay unit 508 delays the correction signal obtained by multiplying the input audio signal IN4 to the speaker SP4 by the coefficient K43 for a predetermined time, and outputs the delayed signal as the audio signal A9 to the adding unit 333.

  The adder 333 performs an adder process for adding the above-described audio signals A7, A8, A9 to the audio signal IN3 input to the speaker SP3 (FIG. 14: step S9), and as an output audio signal OUT3 supplied to the speaker SP3. Output.

<2-2-5: Positive position on the Y axis>
The processing from step S1 to step S4 is the same as that when the viewing position Plp is closest to SP2, and the description thereof is omitted. When it is determined in step S4 that the viewing position Plp has moved from the reference position (FIG. 14: step S4; YES), the control unit 210 calculates the distance from each speaker to the viewing position Plp, The speaker closest to the position Plp is specified. When the control unit 210 determines that the speakers SP1 and SP2 are the speakers closest to the viewing position Plp as shown in FIG. 10, the control unit 210 refers to the table TBL1 stored in the memory 230. The coefficient part to be selected is determined. In the table TBL1 shown in FIG. 4, the coefficient units 400 and 404 are selected when the speaker SP1 and the speaker SP2 are the speakers closest to the viewing position Plp.

  The coefficient used in the coefficient unit 400 is K41 as described above, and the coefficient used in the coefficient unit 404 is K32 as described above.

  The control unit 210 calculates these coefficients by the above formulas (FIG. 14: step S5), and selects the coefficient units 400 and 404 (FIG. 14: step S6). As illustrated in FIG. 3, the delay unit 500 corresponds to the coefficient unit 400, and the delay unit 504 corresponds to the coefficient unit 404. Further, the addition unit 331 and the addition unit 332 correspond to the addition unit. Therefore, the control unit 210 selects the delay unit 500, the delay unit 504, the addition unit 331, and the addition unit 332 (FIG. 14: step S6).

  Next, the control unit 210 passes the coefficients K41 and K32 calculated as described above to the coefficient units 400 and 404, respectively. In the coefficient units 400 and 404, the input audio signal is multiplied by the coefficients K41 and K32 to obtain a correction signal. Is performed to the delay unit (FIG. 14: step S7). Specifically, the coefficient unit 400 outputs a correction signal obtained by multiplying the input audio signal IN4 to the speaker SP4 by the coefficient K41 to the delay unit 500. The coefficient unit 404 outputs a correction signal obtained by multiplying the input audio signal IN3 to the speaker SP3 by the coefficient K32 to the delay unit 504.

  The delay units 500 and 504 perform a delay unit process of delaying the correction signals output from the coefficient units 400 and 404 for a predetermined time and outputting them to the addition units 331 and 332 (FIG. 14: step S8). Specifically, the delay unit 500 delays the correction signal obtained by multiplying the input audio signal IN4 to the speaker SP4 by the coefficient K41 for a predetermined time, and outputs the delayed signal as the audio signal A1 to the adding unit 331. The delay unit 504 delays the correction signal obtained by multiplying the input audio signal IN3 to the speaker SP3 by the coefficient K32 for a predetermined time, and outputs the delayed signal as the audio signal A5 to the adding unit 332.

  The adder 331 performs an adder process for adding the audio signal A1 described above to the audio signal IN1 input to the speaker SP1 (FIG. 14: step S9), and outputs it as the output audio signal OUT1 supplied to the speaker SP1. The adder 332 performs an adder process for adding the audio signal A5 described above to the audio signal IN2 input to the speaker SP2 (FIG. 14: step S9), and outputs it as an output audio signal OUT2 supplied to the speaker SP2.

<2-2-6: Negative position on Y-axis>
The processing from step S1 to step S4 is the same as that when the viewing position Plp is closest to SP2, and the description thereof is omitted. When it is determined in step S4 that the viewing position Plp has moved from the reference position (FIG. 14: step S4; YES), the control unit 210 calculates the distance from each speaker to the viewing position Plp, The speaker closest to the position Plp is specified. When the controller 210 determines that the speaker SP4 and the speaker SP3 are the speakers closest to the viewing position Plp as shown in FIG. 11, the controller 210 refers to the table TBL1 stored in the memory 230. The coefficient part to be selected is determined. In the table TBL1 shown in FIG. 4, coefficient units 406 and 409 are selected when the speaker SP4 and the speaker SP3 are the speakers closest to the viewing position Plp.

  The coefficient used in the coefficient unit 406 is K23 as described above, and the coefficient used in the coefficient unit 409 is K14 as described above.

  The control unit 210 calculates these coefficients by the above formulas (FIG. 14: step S5), and selects the coefficient units 406 and 409 (FIG. 14: step S6). As illustrated in FIG. 3, the delay unit 506 corresponds to the coefficient unit 406, and the delay unit 509 corresponds to the coefficient unit 409. Further, the addition unit 333 and the addition unit 334 correspond to the addition unit. Therefore, the control unit 210 selects the delay unit 506, the delay unit 509, the addition unit 333, and the addition unit 334 (FIG. 14: step S6).

  Next, the control unit 210 passes the coefficients K23 and K14 calculated as described above to the coefficient units 406 and 409, respectively. In the coefficient units 406 and 409, the input audio signal is multiplied by the coefficients K23 and K14 to obtain a correction signal. Is performed to the delay unit (FIG. 14: step S7). Specifically, the coefficient unit 406 outputs a correction signal obtained by multiplying the input audio signal IN2 to the speaker SP2 by the coefficient K23 to the delay unit 506. The coefficient unit 409 outputs a correction signal obtained by multiplying the input audio signal IN1 to the speaker SP1 by the coefficient K14 to the delay unit 509.

  The delay units 506 and 509 perform a delay unit process of delaying the correction signals output from the coefficient units 406 and 409 for a predetermined time and outputting them to the addition units 333 and 334 (FIG. 14: step S8). Specifically, the delay unit 506 delays the correction signal obtained by multiplying the input audio signal IN2 to the speaker SP2 by the coefficient K23 for a predetermined time, and outputs the delayed signal as the audio signal A7 to the adding unit 333. The delay unit 509 delays the correction signal obtained by multiplying the input audio signal IN1 to the speaker SP1 by the coefficient K14 for a predetermined time, and outputs the delayed signal as the audio signal A10 to the adding unit 334.

  The adder 333 performs an adder process for adding the audio signal A7 described above to the audio signal IN3 input to the speaker SP3 (FIG. 14: step S9), and outputs the output audio signal OUT3 supplied to the speaker SP3. The adder 334 performs an adder process for adding the audio signal A10 described above to the audio signal IN4 input to the speaker SP4 (FIG. 13: step S6), and outputs the output audio signal OUT4 supplied to the speaker SP4.

<2-2-7: Negative position on the X axis>
The processing from step S1 to step S4 is the same as that when the viewing position Plp is closest to SP2, and the description thereof is omitted. When it is determined in step S4 that the viewing position Plp has moved from the reference position (FIG. 14: step S4; YES), the control unit 210 calculates the distance from each speaker to the viewing position Plp, The speaker closest to the position Plp is specified. When the control unit 210 determines that the speakers SP1 and SP4 are the speakers closest to the viewing position Plp as shown in FIG. 12, the control unit 210 refers to the table TBL1 stored in the memory 230. The coefficient part to be selected is determined. In the table TBL1 shown in FIG. 4, coefficient units 402 and 411 are selected when the speaker SP1 and the speaker SP4 are the speakers closest to the viewing position Plp.

  The coefficient used in the coefficient unit 402 is K21 as described above, and the coefficient used in the coefficient unit 411 is K34 as described above.

  The control unit 210 calculates these coefficients using the above equations (FIG. 14: step S5), and selects the coefficient units 402 and 411 (FIG. 14: step S6). As illustrated in FIG. 3, the delay unit 502 corresponds to the coefficient unit 402, and the delay unit 511 corresponds to the coefficient unit 411. Further, the addition unit 331 and the addition unit 334 correspond to the addition unit. Therefore, the control unit 210 selects the delay unit 502, the delay unit 511, the addition unit 331, and the addition unit 334 (FIG. 14: step S6).

  Next, the control unit 210 passes the coefficients K21 and K34 calculated as described above to the coefficient units 402 and 411, respectively. In the coefficient units 402 and 411, the input audio signal is multiplied by the coefficients K21 and K34 to obtain a correction signal. Is performed to the delay unit (FIG. 14: step S7). Specifically, the coefficient unit 402 outputs to the delay unit 502 a correction signal obtained by multiplying the input audio signal IN2 to the speaker SP2 by the coefficient K21. The coefficient unit 411 outputs a correction signal obtained by multiplying the input audio signal IN3 to the speaker SP3 by the coefficient K34 to the delay unit 511.

  The delay units 502 and 511 perform delay unit processing that delays the correction signals output from the coefficient units 402 and 411 for a predetermined time and outputs them to the addition units 331 and 334 (FIG. 14: step S8). Specifically, the delay unit 502 delays a correction signal obtained by multiplying the input audio signal IN2 to the speaker SP2 by the coefficient K21 for a predetermined time, and outputs the delayed signal as the audio signal A3 to the adding unit 331. The delay unit 511 delays the correction signal obtained by multiplying the input audio signal IN3 to the speaker SP3 by the coefficient K34 for a predetermined time, and outputs the delayed signal as the audio signal A12 to the adding unit 334.

  The adder 331 performs an adder process for adding the audio signal A3 described above to the audio signal IN1 input to the speaker SP1 (FIG. 14: step S9), and outputs it as an output audio signal OUT1 supplied to the speaker SP1. The adder 334 performs an adder process for adding the audio signal A12 described above to the audio signal IN4 input to the speaker SP4 (FIG. 14: step S9), and outputs it as an output audio signal OUT4 supplied to the speaker SP4.

<2-2-8: Positive position on the X axis>
The processing from step S1 to step S4 is the same as that when the viewing position Plp is closest to SP2, and the description thereof is omitted. When it is determined in step S4 that the viewing position Plp has moved from the reference position (FIG. 14: step S4; YES), the control unit 210 calculates the distance from each speaker to the viewing position Plp, The speaker closest to the position Plp is specified. When the control unit 210 determines that the speaker SP2 and the speaker SP3 are the closest speakers to the viewing position Plp as shown in FIG. 13, the control unit 210 refers to the table TBL1 stored in the memory 230. The coefficient part to be selected is determined. In the table TBL1 shown in FIG. 4, coefficient units 403 and 408 are selected when the speaker SP2 and the speaker SP3 are the speakers closest to the viewing position Plp.

  The coefficient used in the coefficient unit 403 is K12 as described above, and the coefficient used in the coefficient unit 408 is K43 as described above.

  The control unit 210 calculates these coefficients using the above equations (FIG. 14: step S5), and selects the coefficient units 403 and 408 (FIG. 13: step S3). As illustrated in FIG. 3, the delay unit 503 corresponds to the coefficient unit 403, and the delay unit 508 corresponds to the coefficient unit 408. Further, the addition unit 332 and the addition unit 333 correspond to the addition unit. Therefore, the control unit 210 selects the delay unit 503, the delay unit 508, the addition unit 332, and the addition unit 333 (FIG. 14: step S6).

  Next, the control unit 210 passes the coefficients K12 and K43 calculated as described above to the coefficient units 403 and 408, respectively. In the coefficient units 403 and 408, the input audio signal is multiplied by the coefficients K12 and K43 to obtain a correction signal. Is performed to the delay unit (FIG. 14: step S7). Specifically, the coefficient unit 403 outputs a correction signal obtained by multiplying the input audio signal IN1 to the speaker SP1 by the coefficient K12 to the delay unit 503. The coefficient unit 408 outputs a correction signal obtained by multiplying the input audio signal IN4 to the speaker SP4 by the coefficient K43 to the delay unit 508.

  The delay units 503 and 508 delay the correction signals output from the coefficient units 403 and 408 for a predetermined time and perform delay unit processing to output to the addition units 332 and 333 (FIG. 14: step S8). Specifically, the delay unit 503 delays the correction signal obtained by multiplying the input audio signal IN1 to the speaker SP1 by the coefficient K12 for a predetermined time, and outputs the delayed signal as the audio signal A4 to the adding unit 332. The delay unit 508 delays the correction signal obtained by multiplying the input audio signal IN4 to the speaker SP4 by the coefficient K43 for a predetermined time, and outputs the delayed signal as the audio signal A9 to the adding unit 333.

  The adder 332 performs an adder process for adding the above-described audio signal A4 to the input audio signal IN2 to the speaker SP2 (FIG. 14: step S9), and outputs it as an output audio signal OUT2 to be supplied to the speaker SP2. The adder 333 performs an adder process for adding the audio signal A9 described above to the audio signal IN3 input to the speaker SP3 (FIG. 14: step S9), and outputs the output audio signal OUT3 supplied to the speaker SP3.

<2-3: Hearth effect processing>
In the present embodiment, when the overall volume level is lower than a predetermined level and the distance from each speaker to the viewing position Plp is different, that is, when the viewing position Plp is moved from the reference position Pref, The output signal of each speaker whose distance to the viewing position Plp is longer than the distance from the reference position Pref is output from the speaker closest to the viewing position Plp. Therefore, for example, in the case of FIG. 6, since the signal output from the speaker SP3, which is originally a rear speaker, is also output from the front speaker SP2, there is a possibility that it differs from the preset acoustic effect. Therefore, in the present embodiment, the Haas effect, which is a preceding sound effect, is used to delay the correction signal output as a signal that compensates for the lack of volume by a predetermined time using the delay units 500 to 511.

  For example, in the case of FIG. 6, when the input audio signal IN3 to the speaker SP3 is multiplied by the coefficient K32 by the coefficient unit 404, this signal is delayed by 10 to 20 ms by the delay unit 504, and is sent to the adder 332 as the audio signal A5. Output. As a result, the audio signal A5 described above is added to the input audio signal IN2 to the speaker SP2, and is output as the output audio signal OUT2 from the speaker SP2. The added audio signal A5 is output from the speaker SP3. The signal is output from the speaker SP2 with a delay of 10 to 20 ms from the signal. That is, the signal output from the speaker SP3 is output 10 to 20 ms earlier than the added audio signal A5 output from the speaker SP2. The signal output from the speaker SP3 is an output audio signal OUT3 from which the input audio signal IN3 to the speaker SP3 is output as it is, and the audio signal A5 is a signal obtained by multiplying the input audio signal IN3 by a coefficient K32. That is, both signals are signals having the source as the input audio signal IN3. When a signal having a common source is output from one speaker earlier by a predetermined time than the other speaker, the viewer It feels like a signal is being output from the one speaker. In the present embodiment, the Haas effect is used to make it feel as if it is output from the speaker that is originally output, even when output from a speaker that is different from the speaker that is originally output. .

  In the present embodiment, as shown in FIG. 3, the coefficient units 400 to 411 and the delay units 500 to 511 are provided in a pair, and when the control unit 210 selects any coefficient unit as described above, The control unit 210 selects a delay unit paired with the selected coefficient unit. In this embodiment, a delay time of about 10 to 20 ms is employed by the delay unit. This is because if there is a delay difference greater than this, it will be heard by another sound source.

  As described above, according to this embodiment, even when the overall volume level is lower than the predetermined level and the distance from the speaker to the viewing position is longer than the predetermined distance, a balance can be obtained. Sound effect can be obtained.

<Modification>
The present invention is not limited to the above-described embodiments, and various modifications described below are possible. Moreover, each modification and embodiment mentioned above can be combined suitably.

(1) In the above-described embodiment, an example in which the distance from each speaker to the viewing position is acquired and the speaker closest to the viewing position is determined has been described. You may make it judge a near speaker.

(2) In each of the above-described embodiments, the case where the shape of the listening room is square has been described. However, the present invention is not limited to such an example. For example, the shape of the listening room is rectangular. Also good. The listening room may be trapezoidal or asymmetric. In this case, a predetermined position is set as the reference position of the viewing position, and the volume of the output audio signal from each speaker is set so that the volume from each speaker has a desired balance at the reference position. Then, the set sound volume is set as a reference sound volume of each speaker, and the coefficient of each coefficient portion when the actual viewing position is displaced from the reference position may be calculated.

DESCRIPTION OF SYMBOLS 1A ... Audio signal processing system, 10 ... Terminal device, 20 ... Audio signal processing device, 210 ... Control part, 220 ... Communication interface, 230 ... Memory, 240 ... External interface, 250, 260 ... Processing unit, 400, 401, 402 , 403, 404, 405, 406, 407, 408, 409, 410, 411 ... coefficient part, 500, 501, 502, 503, 504, 505, 506, 507, 508, 509, 510, 511 ... delay part, 331 , 332, 333, 334 ... adder, SP1, SP2, SP3, SP4, SP5 ... speaker

Claims (3)

A distance acquisition unit that acquires distances from a plurality of speakers to a viewing position;
A volume acquisition unit for acquiring the overall volume;
The volume acquired by the volume acquisition unit is less than or equal to a predetermined volume, and the viewing position moves from a reference position at a predetermined distance relative to the plurality of speakers based on the distance acquired by the distance acquisition unit If it is determined that the output volume of the output audio signal for the speaker far from the viewing position is corrected with respect to the output volume and the viewing position acquired by the distance acquisition unit. A calculation unit for calculating based on the distance from the speaker on the near side to the viewing position;
An addition unit that adds the correction amount to the output audio signal of the speaker closer to the viewing position while maintaining the output volume of the output audio signal of the speaker far from the viewing position ;
An audio signal processing apparatus comprising: The distance acquisition unit acquires distances from the plurality of speakers to the viewing position based on respective coordinates of the plurality of speakers and coordinates of the viewing position. Audio signal processing device. It has a delay unit that delays the audio signal for a predetermined time,
The audio signal processing apparatus according to claim 1, wherein the adding unit adds the correction amount delayed by a predetermined time by the delay unit to the output audio signal.

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