JP2018137532A - Gain setting apparatus, gain setting method, and gain setting program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gain setting device capable of amplifying sound with a sound pressure as high as possible in the entire room without howling.SOLUTION: A gain setting apparatus includes at least one microphone (11) for picking up sound, a plurality of speakers 21 to 29, a master volume reception unit 31, and an adjustor 32 that obtains an open loop gain in each system in a combination of the plurality of speakers 21 to 29 and the microphone 11 and adjusts a gain of each of the systems such that the loop gain does not exceed a predetermined value according to the obtained open loop gain and a master volume received at the master volume reception unit 31.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a gain setting device, a gain setting method, and a gain setting program related to off-microphone sound collection.

  2. Description of the Related Art Conventionally, there has been proposed a loudspeaker device that is used in a conference with a large number of people, for example, to perform loudspeaking without controlling howling by controlling the sound pressure distribution (see, for example, Patent Document 1). In addition, there has been proposed one that suppresses howling by letting sound from a loudspeaker speaker present not only to an attendee away from a microphone but also to an attendee close to the microphone (see, for example, Patent Document 2). ).

JP-A-48-82709 JP-A-51-98903

  However, in the methods disclosed in Patent Document 1 and Patent Document 2, when adjustment is performed so that each speaker is basically serviced with the same sound pressure, howling is likely to occur in a speaker close to a microphone. For this reason, the sound pressure cannot be increased even in a speaker far from the microphone. Therefore, it is difficult to make loud sound so that loud sound is dominant throughout the room. Further, in order to increase the sound pressure of the speaker far from the microphone, manual adjustment for each speaker is necessary.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a gain setting device, a gain setting method, and a gain setting program capable of performing loudspeaking with a sound pressure as high as possible throughout the entire room without howling.

  The gain setting device of the present invention acquires an open loop gain in each system in a combination of at least one microphone that collects sound, a plurality of speakers, a master volume receiving unit, and the plurality of speakers and the microphone. And an adjuster that adjusts the gain of each system so that the loop gain does not exceed a predetermined value according to the acquired open loop gain and the master volume received by the master volume receiving unit. To do.

  The gain setting device of the present invention acquires an open loop gain in each system in a combination of a microphone and a plurality of speakers. Since the gain setting device adjusts the gain in accordance with the acquired open loop gain and master volume, the loudspeaker can be amplified with the highest sound pressure in the entire room. Moreover, since the gain setting device sets the gain of each system so that the loop gain of each system does not exceed a predetermined value, occurrence of howling can be suppressed.

  According to the present invention, the gain setting device adjusts the gain in each system in the combination of the microphone and the plurality of speakers, and sets the gain of each system so that the loop gain of each system does not exceed the predetermined value. The sound can be loudened with the highest sound pressure in the entire room without howling.

It is a top view of the room where the gain setting device concerning a first embodiment was installed. It is sectional drawing of the room | chamber interior where the gain setting apparatus which concerns on 1st embodiment was installed. It is a block diagram which shows the structure of the gain setting apparatus which concerns on 1st embodiment. It is a flowchart which shows operation | movement of information processing apparatus. It is a figure for demonstrating the method of acquiring an open loop gain. 6A is an example of the relationship between the open loop gain and the master volume in the speakers 21 to 23, and FIG. 6B is a graph illustrating an example of the relationship between the gain Gn and the master volume in the speakers 21 to 23. It is. 7A is an example of the relationship between the open loop gain and the master volume in the speakers 21 to 23, and FIG. 7B is a graph illustrating an example of the relationship between the gain Gn and the master volume in the speakers 21 to 23. It is. 8A is a graph showing an example of the relationship between the open loop gain and the master volume in the speakers 21 to 23, and FIG. 8B is a graph showing an example of the relationship between the gain Gn and the master volume in the speakers 21 to 23. It is. FIG. 9A shows an example of the relationship between the open loop gain and the master volume in the speakers 21 to 23, and FIG. 9B shows a graph showing an example of the relationship between the gain Gn and the master volume in the speakers 21 to 23. It is. It is a top view of the room | chamber interior where the gain setting apparatus which concerns on 2nd embodiment was installed. It is a block diagram which shows the structure of the gain setting apparatus which concerns on 2nd embodiment. FIG. 12A is a plan view of a room where the loudspeaker system according to the third embodiment is installed, and FIG. 12B is a cross-sectional view of the room where the loudspeaker system according to the third embodiment is installed. is there. It is a graph which shows the relationship between a listening position and a sound pressure level in an Example.

  FIG. 1 is a plan view of a room in which a gain setting device 1 according to the first embodiment is installed, and FIG. 2 is a cross-sectional view (a cross-sectional view taken along plane AA shown in FIG. 1). FIG. 3 is a block diagram showing the configuration of the gain setting device 1. The gain setting device 1 is installed, for example, in a room where a large number of conferences, workshops, etc. are held, and a speaker's voice is amplified and emitted to a listener.

  The gain setting device 1 includes a microphone 11, a plurality of speakers (9 speakers 21 to 29 in this example), and a signal processing device 4. The signal processing device 4 includes a master volume receiving unit 31 and an adjuster 32. In addition, the gain setting device 1 includes an oscillator 34, a monitoring device 35, or an information processing device 5. Although not necessarily required, the oscillator 34 generates a sound such as white noise or pink noise in order to acquire an open loop gain described later. The gain setting device 1 may include a feedback suppressor 30, an amplifier 40 to an amplifier 49, a matrix mixer 33, or the like as necessary.

  In the example of FIG. 2, the gain setting device 1 is installed by suspending the microphone 11 downward from the indoor ceiling. However, the installation mode of the microphone 11 is not limited to the example of FIG. The microphone 11 may be installed at a position away from the speaker T. For example, the installation position of the microphone 11 may be a position embedded in the ceiling. Note that the microphone 11 may be installed in the vicinity of the speaker T and is not limited to the position on the listeners L1 to L9 side from the speaker T. For example, the microphone 11 may be located above the speaker T or from the speaker T. It may be installed at a position opposite to the listeners L1 to L9.

  The gain setting device 1 has a plurality of speakers 21 to 29 installed indoors at a position embedded in the ceiling. However, the installation mode of the plurality of speakers 21 to 29 is not limited to the example of FIG. For example, the gain setting device 1 may be installed by suspending a plurality of speakers 21 to 29 downward from the indoor ceiling in the same manner as the microphone 11.

  The gain setting device 1 has a plurality of speakers arranged in a matrix in plan view as shown in FIG. The gain setting device 1 is provided with a plurality of speakers 21 to 29 around the listeners L1 to L9. The installation position of the speaker 21 is the position closest to the microphone 11. In FIG. 1, the direction in which the microphone 11 is installed as viewed from the speaker 21 is the X direction, and the direction orthogonal to the X direction is the Y direction. The installation positions of the speakers 24 and 27 are arranged along the Y direction in the same column as the speakers 21 with the speakers 21 as the center row. The speaker 22 is installed in the center row in the same manner as the speaker 21, and is farther from the microphone 11 than the speaker 21. The installation positions of the speakers 25 and 28 are arranged along the Y direction in the same column as the speakers 22 with the speakers 22 as the center row. The installation position of the speaker 23 is installed in the center row like the speaker 21, and is farther from the microphone 11 than the speaker 22. The installation positions of the speakers 26 and 29 are arranged along the Y direction in the same column as the speakers 23 with the speakers 23 as the center row. A combination of the microphone 11 and the plurality of speakers 21 to 29 constitutes each system. In addition, the number of speakers and the installation mode in plan view are not limited to the examples shown in FIGS.

As shown in FIG. 2, sound is transmitted in the room in the first transfer function H _{T1, Mi of} the first system from the position of the speaker T to the microphone 11 and from the position of the speaker T to a plurality of listeners Ln. Second transfer function H _{T1, Ln of} the second system reaching the position (n = 1 to 9 in this example), the third system reaching the positions of the plurality of listeners Ln from the plurality of speakers Sn (n = 1 to 9) The third transfer function H _{Sn, Ln} and the fourth transfer function H _{Sn, Mi} of the fourth system from the plurality of speakers Sn to the microphone 11 are shown. For example, the transfer function of the sound that the microphone 11 directly picks up the sound produced by the speaker _T is H _{T1, M1, and} the transfer function of the sound that the microphone 11 picks up the sound emitted from _the speaker 21 is H _S1, It is shown by a function called _M1 . The transfer function of the sound that the listener L1 listens directly from the sound produced by _the speaker _T is H _{T1 and L1, and} the transfer function of the sound that the listener L1 listens to the sound emitted from _the speaker 21 is H _{S1 and L1.} Indicated by function.

  Inside the lecture room R, the sound pressure at the position of the listener Ln is the sum of the sound pressure of the sound emitted by the speaker T and the sound pressure of the sound emitted from the speaker at the position of the listener Ln. Correspond. Generally, the closer the distance from the speaker T to the listener Ln, the larger the sound transmitted from the speaker T to the listener Ln, and the longer the distance from the speaker T to the listener Ln, the greater the distance from the speaker T to the listener Ln. The sound transmitted to is reduced. For this reason, it is necessary to increase the sound pressure so that the listener Ln far from the speaker T can be heard by the adjuster 32 adjusting the gain Gn of the speaker. Moreover, the loop gain increases as the distance from the speaker to the microphone 11 decreases. For this reason, howling occurs more easily as the distance from the speaker to the microphone 11 is shorter. The adjuster 32 adjusts the gain of each system in the combination of the microphone 11 and each of the speakers 21 to 29 so that howling does not occur.

  In the example of FIG. 2, the speaker T is located below the microphone 11. The microphone 11 picks up the sound produced by the speaker T. The gain setting device 1 inputs the sound signal related to the sound acquired by the microphone 11 to the signal processing device 4 after being amplified by the amplifier 40.

  The signal processing device 4 first inputs the sound signal input to the signal processing device 4 to the feedback suppressor 30. As the feedback suppressor 30, for example, a notch filter type is used, and a loop gain peak is removed. Next, the signal processing device 4 inputs the sound signal to the matrix mixer 33. The matrix mixer 33 distributes the input sound signal to a plurality of systems (in this example, nine systems equal to the number of speakers).

The master volume receiving unit 31 receives a master volume input by the user. The gain adjustment method will be described in detail later, but the adjuster 32 adjusts the gain of each system in the combination of the microphone 11 and each speaker (speaker 21 to speaker 29). The adjuster 32 adjusts the gain of the input sound signal in the gain adjusters 321 to 329 of each system and outputs the gain to the amplifiers 41 to 49. Regulator 32 may be, for example, as a _{G 1} gain corresponding to the speaker 21, the gain corresponding to the speaker 22 as _{G 2,} gain corresponding to the speaker 23 as a _{G 3,} adjusted respectively.

  The speaker amplifiers 41 to 49 amplify the input sound signals and output them to the speakers 21 to 29.

  In this way, the gain setting device 1 adjusts the gain for each of the speakers 21 to 29 and delivers the sound acquired by the microphone 11 to the listeners L1 to L9.

  The information processing apparatus 5 is composed of a personal computer, for example. The information processing apparatus 5 includes a control unit 6 and a storage unit 7. When the control unit 6 executes the gain setting program stored in the storage unit 7, the open loop gain acquisition unit 51, the gain calculation unit 52, and the gain setting unit 53 illustrated in FIG.

  FIG. 4 is a flowchart showing the operation of the information processing apparatus 5. Hereinafter, the gain setting method will be described. First, the open loop gain acquisition unit 51 acquires the open loop gain of each system in the combination of the microphone 11 and each speaker (speakers 21 to 29) in the room (s11).

  FIG. 5 is a diagram for explaining a method of acquiring an open loop gain. As shown in FIG. 5, the open loop gain acquisition unit 51 individually acquires the open loop gain for each system in the combination of the microphone 11 and each speaker (speakers 21 to 29). For example, the combination of the microphone 11 and the speaker 23 is mentioned. For example, a state where a speaker T and a listener L3 are present inside the lecture room R is virtually configured. With the switch 55 provided between the microphone 11 and the speaker 23 being turned off, the oscillator 34 generates white noise. The monitoring device 35 detects white noise generated by the oscillator 34. IN1 is obtained by directly detecting white noise generated by the oscillator 34 by the monitoring device 35. In contrast, IN2 is detected by the monitoring device 35 via the speaker 23 and the microphone 11. More specifically, the speaker 23 emits white noise generated by the oscillator 34 from the speaker 23. The microphone 11 collects white noise emitted from the speaker 23 and passing through the inside of the lecture room R. The monitoring device 35 detects the sound collected by the microphone 11 as IN2.

  The acquisition of the open loop gain is performed based on the following formula 1 when the reference gain Gn is set to 0 dB, for example.

(Formula 1) Open Loop Gain = 10 log 10 ((IN2 / IN1) ² )
The open loop gain acquisition unit 51 accepts inputs such as a room shape, a microphone position, a speaker position, a listening position, a speaker position, and the like, and estimates each open loop gain by numerical simulation or data prepared in advance. Thus, each open loop gain may be acquired automatically. In this case, the open loop gain acquisition unit 51 estimates each open loop gain based on the data of the various conditions stored in the storage unit 7. This eliminates the trouble of acquiring the open loop gain every time it is used.

  The gain calculation unit 52 calculates the gain Gn of each system from the microphone 11 to the plurality of speakers Sn using the open loop gain and master volume acquired by the open loop gain acquisition unit 51 (s12).

  The gain setting unit 53 sets information on the calculated gain Gn of each system for each speaker and transmits the information to the adjuster 32. The gain Gn of each system corresponds to the gain setting value to be set in the gain adjuster 321 to the gain adjuster 329 of each system in the adjuster 32 shown in FIG. Hereinafter, a method for adjusting the gain Gn of each system will be described.

  6A is an example of the relationship between the open loop gain and the master volume in the speakers 21 to 23, and FIG. 6B is a graph illustrating an example of the relationship between the gain Gn and the master volume in the speakers 21 to 23. It is. The gain calculation unit 52 calculates the gain of each system so that the loop gain does not exceed a predetermined value according to the acquired open loop gain and the master volume received by the master volume reception unit 31. The gain Gn can be expressed as some function with respect to the master volume of the open loop gain. The condition where no howling occurs is when the loop gain is less than 0 dB. The loop gain is a value that does not sufficiently howling, for example, −6 dB. When the adjuster 32 sets the loop gain so as not to exceed −6 dB, howling can be prevented. Examples of gain adjustment modes for each system are shown below. As a gain adjustment mode, the positions of the speakers 21 to 23 will be described for convenience of explanation.

  In the setting modes shown in FIGS. 6A and 6B, the gain calculation unit 52 similarly increases each gain in conjunction with the increase in the master volume, but the loop gain is set to a predetermined value (−6 dB) for each system. ) Limit the gain so that: For example, when the gain G1 of the speaker 21 is 0 dB, the master volume is 0 dB, and the open loop gain measured in advance is +18 dB, if the loop gain is set to −6 dB, the gain G1 when the master volume is 0 dB is −24 dB. Must be set to Therefore, the gain calculation unit 52 limits the gain G1 to −24 dB. Thereby, even if the master volume is increased, the loop gain does not exceed the predetermined value of −6 dB. For example, if the gain G2 of the speaker 22 is 0 dB and the open loop gain measured when the master volume is 0 dB is +15 dB, the gain G2 for setting the loop gain to −6 dB is −21 dB. Similarly, if the gain G3 of the speaker 23 is 0 dB and the open loop gain measured when the master volume is 0 dB is +5 dB, the gain G3 for setting the loop gain to −6 dB is −11 dB. Therefore, the gain calculation unit 52 limits the gain G2 to -21 dB and the gain G3 to -11 dB even if the master volume is increased. Generally, as the distance between the microphone and the speaker increases, the volume of sound returning from the speaker to the microphone decreases and the loop gain also decreases. For this reason, when the master volume is increased, the gain of the speaker near the microphone does not increase at a lower volume position than the gain of the speaker far from the microphone. As a result, the gain setting unit 53 can set a larger gain as the master volume increases as the distance between the speaker and the microphone 11 increases. Therefore, the gain setting device 1 can increase the sound emitted from the speaker as the distance between the speaker and the microphone 11 increases.

  7A is an example of the relationship between the open loop gain and the master volume in the speakers 21 to 23, and FIG. 7B is a graph illustrating an example of the relationship between the gain Gn and the master volume in the speakers 21 to 23. It is. The setting mode shown in FIGS. 7A and 7B is an example of a mode in which the rate of gain change with respect to the master volume is different for each system. The gain calculation unit 52 calculates the loop gain to increase until a predetermined value (−6 dB) regardless of the positions of the speakers 21 to 23. In this setting, the rate of increase of the loop gain with respect to the increase of the master volume is different at the positions of the speakers 21 to 23. In this case, the gain setting unit 53 can make a setting according to the usage situation by changing the ratio of the gain increase to the master volume increase for each position of the speakers 21 to 23.

  8A is a graph showing an example of the relationship between the open loop gain and the master volume in the speakers 21 to 23, and FIG. 8B is a graph showing an example of the relationship between the gain Gn and the master volume in the speakers 21 to 23. It is. 8A and 8B, the gain calculation unit 52 has the same open loop gain regardless of the positions of the speakers 21 to 23, and the loop gain until the predetermined value (−6 dB) is reached. Is calculated so as to increase. In this setting, the gain is set smaller as the speaker is always closer to the microphone.

  FIG. 9A shows an example of the relationship between the open loop gain and the master volume in the speakers 21 to 23, and FIG. 9B shows a graph showing an example of the relationship between the gain Gn and the master volume in the speakers 21 to 23. It is. The setting mode shown in FIGS. 9A and 9B is an example of a mode in which the rate of gain change with respect to the master volume is different for each system. The maximum setting value of the master volume is 6 dB. In conjunction with the increase in the master volume, the gain is calculated so as to increase until the loop gain reaches a predetermined value (−6 dB). In this setting, the gain calculation unit 52 always changes the gain when the master volume changes regardless of the positions of the speakers 21 to 23. If the volume does not change even when the master volume is changed, the user may feel uncomfortable. However, in the setting modes shown in FIGS. 9A and 9B, the gain calculation unit 52 always changes the gain in conjunction with the change of the master volume, thereby preventing the user from feeling uncomfortable. Can do. In FIGS. 9A and 9B, the relationship between the master volume and the gain is expressed by a straight line, but a relationship in which the rate of change changes in the middle may be used.

  As described above, the adjuster 32 adjusts the gain of each system so that the loop gain does not exceed a predetermined value (−6 dB) according to the acquired open loop gain and the master volume received by the master volume receiving unit 31. . For example, in the case of the combination of the microphone 11 and the speaker 23 shown in FIG. 3 (in the case of the listener L3), the distance between the microphone 11 and the speaker 23 is long and IN2 is relatively small, so the open loop gain is relatively small. Become. For this reason, even if the gain calculation unit 52 increases the gain in accordance with the master volume, howling hardly occurs. Therefore, the gain setting device 1 can increase the sound pressure to such an extent that the listener L3 can sufficiently listen. On the other hand, in the case of the combination of the microphone 11 and the speaker 21 shown in FIG. 3 (in the case of the listener L1), the distance between the microphone 11 and the speaker 21 is short and IN2 is relatively large. It becomes relatively large. However, since the gain calculation unit 52 calculates the gain so that the loop gain does not exceed −6 dB, it is possible to suppress howling that occurs between the microphone 11 and the speaker 21. On the other hand, since the listener L1 is close to the speaker T, the sound from the speaker T can be sufficiently heard even if the gain of the speaker 21 is small.

  The control unit 6 can cause the adjuster 32 to set the gain of each system based on the information indicating the relationship between the open loop gain of each system and the master volume stored in the storage unit 7 in advance. As a result, the user can automatically set the gain of each system only by setting at least the master volume, thereby eliminating the time and effort required for gain adjustment.

  In the above description, the open loop gain and the speaker gain have been handled as single values, respectively, but may be applied for each frequency or frequency band. That is, the gain setting device 1 gives a gain to each speaker for each frequency band so that when one master volume is operated, the gain setting apparatus 1 has a predetermined loop gain or less for each frequency band of each speaker. The gain may be controlled. As a result, it is possible to increase the overall volume without increasing the gain of the frequency band that is easy to perform for each speaker system.

  FIG. 10 is a plan view of a room in which the gain setting device 2 according to the second embodiment is installed. FIG. 11 is a block diagram showing the configuration of the gain setting device 2 according to the second embodiment.

  As shown in FIGS. 10 and 11, the gain setting device 2 according to the second embodiment is the same as the gain setting device 1 according to the first embodiment except that the microphones 11 to 13 and the automixer 36 are provided. It is the same composition. For this reason, description is abbreviate | omitted about the structure similar to the gain setting apparatus 1 which concerns on 1st embodiment. The automixer 36 corresponds to the mixer of the present invention.

  The gain setting device 2 includes microphones 11 to 13, and the microphones 11 to 13 are installed around the speaker T inside the lecture room R. In the gain setting device 2, a combination of microphones 11 to 13 and speakers 21 to 29 constitutes each system. The gain setting device 2 includes amplifiers 401 to 403 connected to the microphones 11 to 13 and an automixer 36 between the microphones 11 to 13 and the feedback suppressor 30. The automixer 36 mixes the sound signals input from the microphones 11 to 13 and outputs them to the subsequent feedback suppressor 30. The automixer 36 automatically adjusts the gain of each microphone according to the level of the sound signal input from the microphones 11 to 13.

  For example, the automixer 36 selects the microphone with the highest level from the sound signals input from the microphones 11 to 13 and outputs the sound signal of the selected microphone to the subsequent stage. Alternatively, the automixer 36 sets the gain of a system with a high level high and sets the gain of a system with a low level low.

The open loop gain acquisition unit 51 calculates the open loop gain Gm, n (m: microphone number, n: speaker number) of each system in the combination of the microphones 11 to 13 and the speakers 21 to 29 based on the above equation 1. get. For example, it is assumed that the microphone 12 is selected in a situation where the speaker T speaks in the vicinity of the microphone 12. In this case, with the same gain Gm, n of the speaker, the open loop gain of the speaker 29 corresponding to the listener L9 furthest from the microphone 12 is relatively small, and the speaker 24 corresponding to the listener L4 closest to the microphone 12 is used. The open loop gain of becomes relatively large. _Therefore, while suppressing small _{G 12,24, G 12,29} can be a large value. Accordingly, the gain setting device 2 can increase the sound pressure of the speaker 29 to such an extent that the listener L9 can sufficiently listen to it, and sets the gain so that the loop gain does not exceed −6 dB. Howling that occurs with the speaker 24 can be suppressed. When the gain is changed by the automixer 36 instead of selecting the microphone, the gain on the speaker side including the change of the gain of the microphone can be determined.

  Further, the case where the speaker T speaks in the vicinity of the microphone 12 and the case where the speaker T speaks in the vicinity of the microphone 13 at the position of the listener L4 is compared. When the speaker T speaks in the vicinity of the microphone 12, the open loop gain of the microphone 12 and speaker 24 system close to the speaker T is relatively large. However, since the gain setting device 2 sets the gain so that the loop gain does not exceed -6 dB, howling that occurs between the microphone 12 and the speaker 24 can be suppressed. On the other hand, when the speaker T speaks in the vicinity of the microphone 13, the open loop gain of the system of the microphone 13 and the speaker 24 far from the speaker T is relatively small. For this reason, the gain setting device 2 can set the gain of the system of the microphone 13 and the speaker 24 large, and can increase the sound pressure of the speaker 24 to such an extent that the listener L4 can sufficiently listen.

  FIG. 12A is a plan view of a room in which the loudspeaker system 1B according to the third embodiment is installed, and FIG. 12B is a cross section of the room in which the loudspeaker system 1B according to the third embodiment is installed. FIG. The gain setting device 3 according to the third embodiment is used when a conference is held with a plurality of persons in a conference room or the like. The gain setting device 3 has the same configuration as that of the gain setting device 2 according to the second embodiment except that it includes a plurality of microphones 61 to 68 and a plurality of speakers 71 to 78 and the arrangement thereof. For this reason, description is abbreviate | omitted about the structure similar to the gain setting apparatus 2 which concerns on 2nd embodiment.

  In the gain setting device 3, speakers T11 to T18 are simultaneously listeners T11 to T18. For this reason, the gain setting device 3 arranges each pair of the microphones 61 to 68 and the speakers 71 to 78 in the vicinity of all the speakers T11 to T18. Thereby, in the gain setting device 3, the combination of the microphones 61 to 68 and the speakers 71 to 78 constitutes each system.

  The open loop gain acquisition unit 51 acquires the open loop gain of each system in the combination of the microphones 61 to 68 and the speakers 71 to 78 based on the above-described Expression 1. For example, a case where the speaker T11 speaks will be described. The open loop gain of the system of the microphone 61 corresponding to the speaker T11 and the speaker 71 closest to the speaker T11 is relatively large. However, since the gain setting device 3 sets the gain so that the loop gain does not exceed -6 dB, howling that occurs between the microphone 61 and the speaker 71 can be suppressed. On the other hand, the open loop gain of the system of the speaker 75 farthest from the microphone 61 and the speaker T11 is relatively small. For this reason, the gain setting device 3 can set the gain of the system of the microphone 61 and the speaker 75 large, and can increase the sound pressure of the speaker 24 to such an extent that the listener T15 can sufficiently listen.

  Further, a comparison is made between the case where the speaker T14 near the listener T15 speaks at the position of the listener T15 and the case where the speaker T11 far from the listener T15 speaks. When the speaker T14 speaks, the open loop gain of the system of the microphone 64 and the speaker 75 corresponding to the speaker T14 is relatively large. However, since the gain setting device 3 sets the gain so that the loop gain does not exceed -6 dB, howling that occurs between the microphone 64 and the speaker 75 can be suppressed. On the other hand, when the speaker T11 speaks, the open loop gain of the system of the microphone 61 and the speaker 75 corresponding to the speaker T11 is relatively small. For this reason, the gain setting apparatus 3 can set the gain of the system | strain of the microphone 61 and the speaker 75 large, and can raise the sound pressure of the speaker 75 to such an extent that listener T15 can fully listen.

  FIG. 13 is a graph showing the relationship between the listening position and the sound pressure level in Example 1 and Comparative Example 1. In Example 1 and Comparative Example 1, the sound pressure level at each position was obtained by setting the listener to be at positions 1, 2, 4 and 8 m from the speaker. In Example 1, the sound pressure level at each position was obtained when the set value of the master volume was set to 6 dB, -6 dB, -12 dB, and -30 dB. In Comparative Example 1, the sound pressure level at each position was obtained when the gain setting device was not used (live voice).

  As shown in FIG. 13, in Example 1, when the set value of the master volume was set to any of 6 dB, -6 dB, -12 dB, or -30 dB, a comparison was made in which live voices were measured at all listening positions. A sound pressure level higher than the result of Example 1 was obtained. As the set value of the master volume was increased from -30 dB to -6 dB at any listening position, the sound pressure level obtained increased. Further, when the set value of the master volume is set to -6 dB or more (when the set value is 6 dB and when the set value is -6 dB), the sound pressure level is the same at any listening position. As described above, when the set value of the master volume is set to −6 dB or more, no difference is seen in the result, and howling does not occur while the sound pressure level is sufficiently increased as the listening position is further away. . Therefore, it has been confirmed that the gain setting device can perform louding with the highest sound pressure in the entire room without causing howling even at a position away from the speaker.

1, 2, 3 ... Gain setting device 6 ... Control unit 7 ... Storage units 11, 12, 13 ... Microphones 21-29 ... Speaker 31 ... Master volume reception unit 32 ... Adjuster 36 ... Automixer (mixer)

Claims (8)

At least one microphone that picks up the sound,
Multiple speakers,
A master volume reception unit,
An open loop gain is acquired for each system in the combination of the plurality of speakers and the microphone, and the loop gain does not exceed a predetermined value according to the acquired open loop gain and the master volume received by the master volume receiving unit. An adjuster for adjusting the gain of each system,
Comprising
Gain setting device.   2. The gain setting device according to claim 1, wherein the adjuster increases the gain until the loop gain reaches the predetermined value in conjunction with an increase in the master volume.   The gain setting device according to claim 2, wherein a gain change rate with respect to the master volume is different for each system.   The gain setting apparatus according to claim 1, wherein the predetermined value is −6 dB. A plurality of the microphones;
A mixer that mixes sound collected from the plurality of microphones with a predetermined gain;
With
The gain setting device according to any one of claims 1 to 4, wherein the gain of each system is set including the predetermined gain of each system of the mixer. A control unit and a storage unit;
The said control part makes the said regulator set the gain of each said system based on the information which shows the relationship between the open loop gain of each system previously stored in the said memory | storage part, and a master volume. The gain setting apparatus in any one of. The process of accepting the master volume at the master volume acceptance unit,
A process of acquiring an open loop gain in each system in a combination of a plurality of speakers and at least one microphone that collects sound;
The adjuster adjusts the gain of each system so that the loop gain does not exceed a predetermined value according to the acquired open loop gain and the master volume received by the master volume receiving unit;
How to set the gain. The process of accepting the master volume at the master volume acceptance unit,
A process of acquiring an open loop gain in each system in a combination of a plurality of speakers and at least one microphone that collects sound;
The adjuster adjusts the gain of each system so that the loop gain does not exceed a predetermined value according to the acquired open loop gain and the master volume received by the master volume receiving unit;
Is a gain setting program that causes the information processing apparatus to execute.