Sound field control unit and sound field controller

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a sound field control unit and a sound field control device that support a sound field by enhancing acoustic effects such as volume, reverberation, and spaciousness by electroacoustic means based on existing room acoustic conditions. This facilitates the introduction of the sound field support system.

【0002】

[Conventional technology]

There was an acoustic feedback system whose principle is shown in Fig. 2 as an electroacoustic realization of control such as reverberation extension based on the existing room acoustic conditions. In this method, the speaker 12 and the microphone 14 are arranged in the room 10 at an appropriate distance, and the sound picked up by the microphone 14 is supplied to the FIR (Finite Impulse Response: non-circulating type) filter 18 via the head amplifier 16. By repeatedly generating a reverberation signal (mainly an initial reflected sound signal), outputting it to the speaker 12 via the amplifier 20, and collecting the sound again, the feeling of volume is increased (increased sound pressure level). This is intended to increase the reverberation feeling (extension of the reverberation time), increase the spread feeling (enhance the lateral reflected sound energy), and the like. According to this, it is possible to create a sound field feeling as if playing in a large space such as a hall, even though the room 10 is actually a small space.

【0003】

Fig. 3 and Fig. 4 show the conventional sound field control device using this acoustic feedback system. Figure 3 shows the arrangement of microphones and speakers. In room 22 such as a music room, four microphones 24 to 27 are installed on the ceiling and four speakers 30 to 33 are installed on the wall. There is. The device main body 36 that controls the whole is configured as an independent device and is installed in the room 22.

【0004】

FIG. 4 shows the circuit configuration. The frequency characteristics of the sound pick-up signals of each microphone 24 to 27 are adjusted by the equalizer 42 via the head amplifiers 38 to 41 to prevent howling, and are initially adjusted by the FIR filter 44. The reflected sound is generated, amplified by the amplifiers 46 to 49, and reproduced from the speakers 30 to 33. The ROM 52 stores the initial reflected sound parameters of various sound field patterns. When the sound field pattern selection operation is performed by the external infrared remote controller transmitter 54, the corresponding sound field pattern selection signal 56 is transmitted and received by the light receiving window 58 of the apparatus main body 36. In response to this, the CPU 60 reads the initial reflected sound parameter of the corresponding sound field pattern from the ROM 52, sets it in the FIR filter 44, and sets the sound field space.

【0005】

The frequency characteristic is adjusted by the equalizer 42 by, for example, one of the following methods. (a) The equalizer 42 is composed of an FIR filter, the characteristics of the room are measured in advance, the characteristics of this FIR filter are set in advance to the inverse characteristics of the room, and the pick-up signals of the microphones 24 to 27 are folded into this FIR filter. Calculate to flatten the frequency characteristics. (b) If the equalizer 42 is composed of a notch filter and howling occurs during actual use, a notch filter is applied to the frequency band in which howling occurs to suppress howling. (c) The equalizer 42 is composed of a graphic equalizer, and a person manually adjusts the graphic equalizer while measuring the characteristics of the room to flatten the frequency characteristics.

【0006】

[Problems to be Solved by the Invention]

In the conventional sound field control device using acoustic feedback, in order to ensure stability against howling, it is common to reset the installation location of the microphone and the speaker each time the space (room) changes. .. At that time, the microphone and the speaker were of course at different positions, and the distance was also changed for each space. In addition, after installation, the open loop gain is adjusted and the transmission frequency characteristics are adjusted for each microphone / speaker combination using a special measuring instrument, and then the presence or absence of howling and coloration in sound quality are confirmed. It was. For this reason, it takes a long time to install and adjust, which is an obstacle to the introduction of the sound field support system.

【0007】

Further, among the methods for adjusting the frequency characteristics by the equalizer 42, the method using the FIR filter requires an advanced calculation means in order to process a huge amount of calculation. Further, since the method using the notch filter deals with howling after it actually occurs, howling cannot be prevented in advance. Moreover, when a large number of peaks of frequency characteristics causing howling exist over a wide band, a large number of notch filters are required. In addition, the method using the graphic equalizer requires a great deal of time and effort because it is adjusted manually.

【0008】

The present invention is intended to solve the problems in the prior art and provide a sound field control unit and a sound field control device that facilitate the introduction of a sound field support system.

【0009】

[Means for solving problems]

According to the present invention, at least a microphone, a speaker, a sound collecting signal switching means, an equalizer, an FIR filter, and an amplifier are integrally incorporated into a unit, and a plurality of units can be connected to each other via a transmission cable. The sound collection signal of another unit is supplied from the transmission cable, and the sound collection signal of the own unit and the sound collection signal of the other unit are sequentially switched by the sound collection signal switching means, so that the connection state of the microphone and the speaker is between a plurality of units. Can be switched between each other. As a result, the transmission characteristics between the microphone and the speaker are averaged, and the coloration is reduced and the howling margin is expanded. Therefore, even if the distance between the speaker and the microphone is fixed in one unit, coloration and howling are less likely to occur, and it becomes easy to automate the adjustment of loop characteristics. In addition, it is easy to install because it is unitized.

【0010】

Further, by continuously and randomly changing the parameters of the FIR filter on the time axis, the frequency characteristics of the FIR filter can be averaged, and coloration and howling can be made less likely to occur.

【0011】

Further, if each unit is provided with an infrared light receiving unit so that the remote control signal received by one of the units is transmitted to the other unit via the transmission cable, the remote control can be operated in a wide range in the room. It can be done and the operability is improved.

【0012】

The structure of the unit is, for example, a vertically long tubular structure in which the housing is installed upright on the floor, and the speaker is installed in the housing so that sound is radiated upward from the upper end opening of the cylinder constituting the housing. Installed, the microphone is installed on the side of the housing so as to pick up the sound around the housing, the electric circuit part is installed inside the housing, and the sound collecting signal input / output terminal can be connected to the transmission cable from the outside. Can be installed on the site. If the housing is configured in a tubular shape in this way, the distance between the speaker and the microphone can be increased, and since the orientation of the speaker and the orientation of the microphone are different, the sound reproduced by the speaker of the own unit is self-produced. The amount of direct wraparound to the unit's microphone can be reduced, making howling less likely to occur.

【0013】

Further, the equalizer is composed of a front equalizer provided between the sound collecting signal switching means and the FIR filter, and a rear equalizer provided between the FIR filter and the amplifier, and at the rear stage of the rear equalizer. An attenuator can be provided, and the equalizer and attenuator before and after these can be automatically adjusted by using the reference signal for measurement and the transmission characteristic measuring means. In this automatic adjustment, the output of the sound collecting signal switching means is fixed to the sound collecting signal of the own unit, and any part of the signal path is cut off to set the open loop state, and the measurement reference signal is set from the cutoff point. Is input and played back by a speaker, and at that time, the frequency characteristic of the signal that is picked up by the microphone of the own unit and returned to the cutoff point is measured by the measuring means, and the frequency characteristic is adjusted to a predetermined flat characteristic. Adjustment in the open loop state where the characteristics of the equalizer on the side are adjusted and then the attenuator is adjusted so that the gain of the loop becomes a predetermined value, and the loop is closed to execute the switching operation of the sound collecting signal switching means. At the same time, a reference signal for measurement is passed through the loop, the frequency characteristic of the loop is measured by the measuring means, and the characteristic of the equalizer on the front side is adjusted so that the frequency characteristic becomes a predetermined flat characteristic. It consists of adjustment in the state.

【0014】

The rear equalizer can be configured with a parametric equalizer in which the center frequency, gain, and Q can be set. In that case, the automatic adjustment can be performed as follows, for example. That is, the measured frequency characteristic is compared with a predetermined target gain, the peak frequency at a portion exceeding the target gain on the frequency characteristic, the difference between the gain and the target gain at the peak frequency, and the peak frequency at the location. The frequency of the intersection that intersects the target gain is detected on both sides of the above, and the sharpness of the characteristic at the relevant point is obtained from these peak frequencies, gain difference, and intersection frequency, and these detected or obtained peak frequencies, gain difference, Set the center frequency, gain, and Q of the rear equalizer to match the sharpness.

【0015】

Further, as the equalizer on the front side, a parametric equalizer in which the center frequency and gain can be set and the Q is fixed can be configured. In that case, the automatic adjustment can be performed as follows, for example. That is, the measured frequency characteristics are compared with a predetermined target gain, the peak frequency at a location exceeding the target gain on the frequency characteristics, and the difference between the gain and the target gain at the peak frequency are detected, respectively, and these are detected. Set the center frequency and gain of the front equalizer to match the detected peak frequency and gain difference.

【0016】

According to the automatic adjustment using these parametric equalizers, since the parametric equalizer can be configured with an IIR filter, for example, the amount of calculation is small and the adjustment can be easily performed, and even for the peaks of the frequency characteristics distributed in a wide band. It can respond flexibly. Moreover, since it is adjusted in advance prior to actual use, howling can be prevented.

【0017】

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below. FIG. 5 shows an example of the sound field control unit of the present invention. The disassembled state is shown in Fig. 6. As shown in FIG. 6, the sound field control unit 62 has a frame 66 erected on a base (pedestal) 64. A circuit unit 68 and an amplifier unit 70 are attached to the frame 66. As the amplifier unit 70, for example, one having a maximum of about 200 W can be used. A speaker system 72 is attached to the upper end of the frame 66 with the sound radiation direction facing upward. A speaker grill 74 is attached to the radial surface of the speaker system 72. A microphone holder 76 is provided on the base 64, and a microphone unit 78 is attached to the microphone holder 76. As the microphone unit 78, for example, an omnidirectional electret type (condesan microphone) is used. The mounting position of the microphone unit 78 is not limited to the lower position of the sound field control unit 62, and may be any other position as long as the sound field can be received flatly.

【0018】

The front cover 80 and the rear cover 82 that make up the housing are attached to the front and rear of the frame 66. Side covers 84,86 are attached to the left and right sides of both covers 80,82. The front cover 80 is provided with a microphone sound receiving port 88 near the lower end, and an infrared light receiving window 90 with an infrared light receiving element and a power display LED 92 are arranged at the upper part. An eyebolt 94 for attaching a fall prevention wire is attached to the upper part of the rear cover 82. As shown in FIG. 5, the front cover 80, the rear cover 82, and the side covers 84, 86 constitute a tubular housing 94 having an substantially elliptical cross section.

【0019】

The sound field control unit 62 is installed upright on the floor at a height of about 1.5 to 2.0 m. Base64 can also be screwed to the floor if desired. The reproduced sound of the speaker system 72 is radiated upward from the upper end opening 96 of the housing 94. The microphone unit 78 is arranged on the front panel 80 side of the side surface of the housing 94, and collects the sound around the sound field control unit 62. The infrared light receiving window 90 receives an infrared command signal transmitted from the infrared remote control transmitter. The power display LED 92 lights up when the power of the sound field control unit 62 is turned on. The microphone unit 78, the speaker system 72, and the power display LED 92 are connected to the circuit unit 68 inside the housing 94 via a signal line (not shown).

【0020】

A rear panel 98 shown in FIG. 7 is arranged below the rear cover 82. On the rear panel 98, a male connector 100 is arranged as a forward output connector (reverse input connector), and a female connector 102 is arranged as a forward input connector (reverse output connector). .. The forward signal input from the connector 102 is taken into the circuit unit 68 and used, and is output from the connector 100. Further, the reverse (return) signal input from the connector 100 is taken into the circuit unit 68 and used, and is output from the connector 102. Further, the rear cover 82 is provided with a main power switch 104. The power of the sound field control unit 62 is supplied from the power cord 105. The connectors 100 and 102 are connected to the circuit unit 68 inside the housing 94 via a signal line (not shown). A transmission cable is connected to the connectors 100 and 102 from the outside.

【0021】

FIG. 8 shows an example of arranging the sound field control unit 62 in the room. Room 106 has an area of about 20 to 120 square meters, and four sound field control units 62-1 to 62-4 are arranged at its four corners. The sound field control units 62-1, 62-2, 62-3, 62-4 (referred to as units A, B, C, and D, respectively) are the same and are configured as shown in FIGS. 5 to 7 above. There is. Units A to D are connected to each other by connecting the units AB, BC, and CD to the series with three composite cables (transmission cables) 108, and the sound field control unit 160 is connected as a whole. Configure.

【0022】

The connection structure of units A to D is schematically shown in FIG. The composite cable 108 has a female connector 114 attached to one end and a male connector 116 attached to the other end. The connector 114 is connected to the connector 100 of the sound field control unit 62, and the connector 116 is connected to the connector 102 of another sound field control unit 62.

【0023】

The sound collection signals and control signals (command signals) of the units A to D are transmitted to the composite cable 108. The sound pick-up signal is transmitted in the same manner as the AES / EBU format, for example, and two channels (2 units) of signals are assigned to the pair of signal lines (+,-two) in the composite cable 108 in a time-division manner. 2 channels-serial-transmitted in 24-bit. Further, the composite cable 108 is provided with signal lines in the forward direction and the reverse direction for the same channel. Therefore, the four sound pick-up signals picked up by each unit A to D are transmitted using a total of eight signal lines in the composite cable 108. The composite cable 108 also has four signal lines, and the composite cable 108 is composed of a total of 12 signal lines. The signal assignments for the 12 signal lines are shown below.

【0024】

Signal line Signal type Direction polar sound pickup signal unit 1 Pickup signal order + A + B 2 Pickup signal order --A + B 3 Pickup signal order + C + D 4 Pickup signal order --C + D 5 Reverse sound pickup signal + A + B 6 Reverse sound pickup signal --A + B 7 Reverse sound pickup signal + C + D 8 Reverse sound pickup signal-C + D 9 Control signal + Ten Control signal- 11 word clock 12 Grand According to this, transmission in the forward direction (A B C D) and in the reverse direction (D C B A) by the three composite cables 108 connecting the units A to D in FIG. 9 A route is configured, and the sound pick-up signals and control signals of all units A to D are transmitted to all of the three composite cables 108. For example, the sound pick-up signal of unit B is transmitted to units C and D through signal lines 1 and 2 (that is, forward A + B lines), folded back by unit D, and signal lines 5 and 6 (that is, that is, lines A + B). It is transmitted to unit A through the A + B line in the opposite direction).

【0025】

In addition, each CPU provided in each unit A to D has a function of automatically determining which of A to D the own unit has. This judgment is made as follows. That is, when the units A to D are connected by three composite cables 108, two units are generated in which the composite cable 108 is not connected to the male connector 100 or the female connector 102. First, the unit to which nothing is connected to the female connector 102 recognizes its own unit as unit A as a starting point, and sends the numerical value 1 to the adjacent unit through the control signal line. The unit that receives the number 1 recognizes it as unit B, adds 1 to the number 1 and sends the number 2 to the next unit. The unit that receives the number 2 recognizes it as unit C, adds 1 to the number 2 and sends the number 3 to the next unit. The unit that received the number 3 recognizes it as unit D, and also recognizes that it is the end point because nothing is connected to the male connector 100, adds 1 to the number 3 and sends the number 4 back to the unit of channel A. .. Channel A knows that the total number of units is 4 because the number 4 is returned.

【0026】

In this way, the position of each unit A to D is automatically recognized by itself, and the transmission direction of the sound pick-up signal of the own unit is determined accordingly. That is, the units A to C send out the sound pick-up signal of the own unit in the forward direction (fold back at the unit D), and the unit D sends out the sound pick-up signal of the own unit in the opposite direction. As a result, the sound pick-up signals of all the units A to D are transmitted to the three composite cables 108 connecting the units A to D. In addition, the CPU of unit A manages the whole and issues commands to other units B to D (for example, commands to execute automatic adjustment in the order of A, B, C, D). In addition, unit A becomes the clock master, the master clock generated in unit A is supplied to the word clock line in the composite cable 108, and other units B to D share this clock, so that all units are used. A to D are synchronized. The remote control signal received by the infrared light receiving window 90 of any of the units A to D is taken into the unit and transmitted to all the other units through the control signal line in the composite cable 108. As a result, even if any unit receives the remote control signal, it is transmitted to all the units.

【0027】

The transmission of the control signal between the units A to D will be described. The control signal line consists of two lines, HOT (+) and COLD (-), and both lines are (+) when not in use (when no control signal is transmitted from any unit). , Becomes (+) and (-) only when in use (this in-use state is hereinafter referred to as BUZY). This makes it possible to determine whether the control signal line is in use. All control signals are sent as a set of data called "packets". The unit to transmit first checks the state of the control signal line. If it is BUZY, the control signal line is in use, so wait until it becomes available. When the control signal line is free, set it to BUZY by yourself, acquire the right to transmit, and start transmitting. If the control signal line becomes BUZY due to a cause other than your own, another unit is trying to transmit, so the reception operation starts.

【0028】

The circuit configuration in the sound field control unit 62 is shown in FIG. The part surrounded by the alternate long and short dash line 170 in FIG. 1 can be configured by a DSP (digital signal processor). The sound pick-up signal picked up by the microphone unit 78 is converted into a digital signal by the A / D converter 112 via the head amplifier 110, and the sound pick-up signal is switched via the subtractor 114, the attenuator 116, and the programmable equalizer 124. It is input to the circuit 132. The sound pick-up signals of other units input through the input / output circuit 122 are input to the sound pick-up signal switching circuit 132 via the attenuators 118,120,122 and the programmable equalizers 126,128,130. The sound pick-up signal switching circuit 132 sequentially switches these four sound pick-up signals and outputs them to the subsequent circuit.

【0029】

FIG. 10 shows an example of switching the sound pick-up signal in the sound pick-up signal switching circuit 132 of each unit A to D. According to this, since the sound pick-up signals reproduced by the units A to D are sequentially switched, the transmission frequency characteristics are averaged by the spatial averaging effect, the coloration is reduced, and the howling margin is expanded. The switching cycle can be set to, for example, about 1 to 1/2 of the reverberation time in the room.

【0030】

In the attenuator 118,120,122 and the programmable equalizer 126,128,130, the transmission characteristics and gain when the sound collection signal switching circuit 132 selects and outputs the sound collection signal of another unit (when looping with another unit) determines the sound collection signal of its own unit. It is for adjusting the frequency characteristics and gain of the loop with other units based on the frequency characteristics and gain of the own loop when it is different from the transmission characteristics and gain at the time of selective output (at the time of own loop). is there. As a result, it is possible to compensate for various differences in the arrangement state between the units, and it is possible to support use under special conditions such as a vertically long room or units arranged in a position where they cannot be seen from each other. it can. Since the frequency characteristics and gain of the self-loop are adjusted by the programmable equalizer 140 and the attenuator 142 as described later, the attenuator 116 for the self-loop can normally be left at gain 1, and the programmable equalizer 124 can be used. The characteristics may remain flat with a gain of 1.

【0031】

The sound pick-up signal of the own unit and the sound pick-up signal of another unit transmitted from the previous unit are transmitted to the next unit via the input / output circuit 122.

【0032】

The frequency characteristics of the sound collection signal output from the sound collection signal switching circuit 132 are corrected by the programmable equalizer 134 (closed loop frequency characteristic correction), the initial reflected sound is generated by the FIR filter 138, and the frequency is further corrected by the programmable equalizer 140. The characteristic is corrected (the frequency characteristic correction of the open loop for the own loop), and the gain of the open loop for the own loop is adjusted by the attenuator 142. As shown in FIG. 11, the parameters of the FIR filter 138 are continuously and randomly changed on the time axis. As a result, the frequency characteristics of the FIR filter 138 are averaged, and the coloration is further reduced and the howling margin is further increased. The fluctuation of the parameter time axis is realized by, for example, moving the output tap of the FIR filter 138 uncorrelatedly with a fluctuation range of 0.25 msec to 5 msec. The output of the attenuator 142 is reproduced by the speaker system 72 via the volume 172, the muting circuit 144, and the amplifier unit 70.

【0033】

The howling canceller 148 prevents the occurrence of howling due to the reproduced sound of the sound collection signal of the own unit being directly returned to the own microphone, and this is performed at the timing when the sound collection signal of the own unit is reproduced. The sound pick-up signal is returned to the subtractor 114, and the signal directly returned from the own speaker system 72 to the own microphone unit 78 is canceled.

【0034】

In the infrared remote controller transmitter 150, command operations such as power on / off commands for all units A to D, reverberation pattern switching commands, and adjustment mode start commands are performed. When a reverberation pattern switching command (selection command) is issued, the reflected sound parameter of the corresponding reverberation pattern is read from ROM 152 in the sound field control unit 62, set in the FIR filter 138, and the reverberation pattern is switched. ..

【0035】

The loop characteristic adjustment mode performed at the initial stage when the sound field control unit 62 is installed in the room will be described. When the adjustment mode is started by a command from the infrared remote controller transmitter 150, the adjustment operation is fully automatically executed under the control of the CPU 158 of the unit A. The progress of the adjustment operation is managed by CPU 158 in unit A, which is the core of the entire system. The procedure of the automatic adjustment operation is shown in FIG. When the adjustment start is instructed (S1), the adjustment in the open loop state is started first. That is, the switching operation of the sound collecting signal switching circuit 132 of FIG. 1 is stopped, and only the own loop is utilized (that is, the sound collecting signal of the own unit is continuously output from the sound collecting signal switching circuit 132. ). Then, for example, the signal path between the attenuator 142 and the volume 172 in FIG. 1 (or between the programmable equalizer 140 and the attenuator 142 or between the FIR filter 138 and the programmable equalizer 140) is cut off, and the self-loop is opened. It goes into a loop state. In this state, a reference signal for measurement such as pink noise and white noise is generated from the reference signal generation circuit 154, is input from the volume 172 (or the attenuator 142 or the programmable equalizer 140), and is reproduced by the speaker system 72. The reproduced sound is returned to the microphone unit 78 and collected, and the signal is reverberated by the FIR filter 138 through the attenuator 116 of its own loop, the programmable equalizer 124, the sound collection signal switching circuit 132, and the programmable equalizer 134. A signal is generated. The frequency characteristics and gain of this reverberation signal obtained through the programmable equalizer 140 and the attenuator 142 (or the output of the programmable equalizer 140 or the output of the FIR filter 138) should be measured by the measuring circuit 156 to reduce the prominent peak. The CPU in the unit automatically adjusts the programmable equalizer 140 to flatten the frequency characteristics (S2). For fine peak dips on frequency characteristics, Since it can be solved by averaging by the sound pickup signal switching operation, the frequency that rises as the envelope of the frequency characteristic is reduced. This operation is performed sequentially for all combinations of units A to D and the reverberation pattern.

【0036】

When the frequency characteristics of the own loop for all units A to D are flattened, the transmission characteristics and transmission characteristics are used with the measurement reference signal in the state where the sound pickup signal from the other unit is selected (loop state with the other unit). Measure the gain and adjust the attenuators 118,120,122 and programmable equalizers 126,128,130 to obtain the frequency response and gain of the desired characteristics (eg, the same characteristics as your loop) relative to the frequency response and gain of your loop. (S3). The adjustment procedure is as follows: First, for example, the sound pickup signal switching circuit 132 is sequentially switched for unit A to form a loop with units B, C, and D, and the attenuators 118,120,122 and programmable equalizers 126,128,130 of unit A are adjusted, and when that is completed. Similarly, for units B, C, and D, loops with other units are formed to adjust the attenuators 118, 120, 122 and the programmable equalizers 126, 128, 130, respectively. It is also possible to omit the adjustment in step S3.

【0037】

When this adjustment is completed, it is fixed to its own loop again and its own open loop gain is adjusted. That is, although the frequency characteristics of the own loop should be almost flat by the adjustment in step S2, the characteristics may vary in the case of the equalizer using the IIR filter. That is, while the IIR type equalizer is inexpensive, it has a drawback that the phase characteristics are disturbed. When a large number of IIR type equalizers are used, the amplitude characteristics are also affected, and unintended sharp peaks may occur in the frequency characteristics. If the open loop gain is 0 dB or more, the loop is closed. Oscillates (howling) with. Therefore, the reference signal for measurement is generated again and the frequency characteristics are measured by the measurement circuit 156 so that the peak value in the frequency characteristics becomes the same level as the howling level (the level at which howling is likely to occur when the value becomes larger than this). The attenuator 142 is automatically adjusted to set the loop gain to 0 dB or less (for example, -12 dB) (S4). This operation is sequentially performed for all combinations of reverberation patterns of units A to D.

【0038】

This completes the adjustment in the open loop state, and this time the adjustment in the closed loop state is performed (S5). That is, while closing the loop and executing the switching operation of the sound collecting signal switching circuit 132, the measurement reference signal is put into the loop and reproduced from the speaker 72, and the frequency characteristic of the feedback signal (sound collecting signal) is measured. Measure with circuit 156. Then, the programmable equalizer 134 is adjusted so that the gain of the frequency characteristic does not exceed 0 dB. This operation is sequentially performed for all combinations of units A to D and each reverberation pattern. This completes the adjustment operation (S6).

【0039】

The adjustment amount of the programmable equalizer 124,126,128,130,134,140 and the attenuator 116,118,120,122,142 adjusted by the above automatic adjustment operation is stored in the memory (not shown) in the own unit, and the corresponding adjustment amount is read out in conjunction with the reverberation pattern selection operation. Then, the programmable equalizer 124,126,128,130,134,140 and the attenuator 116,118,120,122,142 are automatically adjusted. This further reduces coloration and further increases the howling margin.

【0040】

Here, an automatic adjustment method when the programmable equalizer 140 is configured with a parametric equalizer will be described. FIG. 13 shows the configuration of the part from the equalizer 140 to the volume 172 in FIG. 1 at the time of adjustment. The center frequency, gain, and Q of the parametric equalizer 140 can be set. A switch SW1 and an adder 174 are arranged between the attenuator 142 and the volume 172. The reference signal generation circuit 154 is composed of, for example, a pink noise generator. The pink noise generated here is added at the addition point 174 via the switch SW2. The measurement circuit 156 is composed of, for example, an FFT analyzer. On / off switching of switches SW1 and SW2 at the time of automatic adjustment and other necessary operations are automatically performed by commands from CPU158.

【0041】

The procedure for automatically adjusting the characteristics of the parametric equalizer 140 will be described with reference to FIG. (1) FFT measurement (S11) When automatic adjustment is commanded, the characteristics of the parametric equalizer 140 are flattened (the characteristics of the other equalizers PEQ1 and PEQ2 in Fig. 1 are also flattened). Also, the gain of the attenuator 142 is set to 0 dB, and the volume 172 is maximized. In addition, switch SW1 is turned off to break the loop, switch SW2 is turned on, and pink noise is supplied from the pink noise generator 154 into the path. This pink noise is reproduced by the speaker system 72, passes through the indoor space, and is picked up by the microphone unit 78. The frequency characteristics of the picked up signal are measured by the FFT analyzer 156.

【0042】

(2) Smoothing process (S12) The calculation result by the FFT analyzer 156 is as shown in Fig. 15 (a), for example, but in order to facilitate the processing by the CPU 158, it is smoothed as shown in Fig. 15 (b). Smoothing is performed, for example, by averaging ± 10 points of FFT data. However, since the frequency width of the FFT data is linear, when viewed on the logarithmic axis, the average is not taken in the low range (100 Hz or less), and the average number of points is gradually increased in the mid range (100 Hz to 1 kHz) to increase the average. In the region (1kHz or higher), smoothing is performed by averaging ± 10 points.

【0043】

To average ± 10 points is to average ± 10 data before and after all FFT data. For example, if the original data of the FFT is f (x) and the averaged data is F (x), [0044]

[Number 1]

<img file="JPH1069280A_D0001.tif" />Then, if this x is performed for all FFT data f (x), the same number of FFT average data F (x) as the original data f (x) is calculated.

【0045】

(3) Equalizing target level setting (S13) Take the average value of the original FFT data, for example, in the mid range (500Hz to 2kHz), and use that as the target level for equalizing. In the example of Fig. 15 (b), -1.5 dB is set as the target level. The average value of 500Hz to 2kHz is taken because it is a band that is empirically less affected by the characteristics of the room.

【0046】

(4) Peak detection and characteristic setting (S14 ~ 16) Find the peak position on the smoothed frequency response (the top of the highest level mountain among the multiple peaks that exist throughout the frequency response). For example, if the target level is exceeded in a certain part of the frequency characteristics as shown in Fig. 16 (a), the frequency f at the peak position₀And the frequency f at the intersection of the target levels on both sides₁, f₂Is detected. And the frequency f at the peak position₀And the frequency f at the intersection with the target level₁, f₂As a ratio with R₁= f₁/ f₀R₂= f₀/ f₂Is calculated and the larger one is adopted.

【0047】

The one with the larger frequency ratio is adopted for the following reasons. That is, when there is a characteristic as shown in FIG. 16 (a), the frequency f is as shown in FIG. 16 (b).₁And f₂The characteristics of the equalizer that match each of these can be considered. In this case, the frequency ratio is small f₁The characteristic EQ1 of the equalizer that matches the one becomes a broad (dull) characteristic, and as a result, the required band is scraped off. Therefore, f has a large frequency ratio so as not to cut too much.₂Set to EQ2, which is a sharp equalizer characteristic that matches the direction of. However, in this case, uncut parts are left uncut, so the simulation calculation in step S17, which will be described later, is performed, and the equalizer characteristics are further set.

【0048】

Then, the difference GdB between the target level and the peak position level is obtained. Then, these obtained frequency ratios R₁Or R₂And the level difference GdB, find the Q required to bring this peak below the target level. For this purpose, for example, the frequency ratio for each combination of the level difference G and Q as shown in Table 1 is created as a table and prepared in advance in the memory (not shown), and the obtained level difference GdB is obtained. (If the corresponding level difference is not in the table, the closest level difference), select the Q that gives the frequency ratio closest to the obtained frequency ratio.

【0049】

[table 1]

<img file="JPH1069280A_D0002.tif" />From the above, the frequency f at the peak position₀Once the level difference GdB, Q is determined, the characteristics of one band of the parametric equalizer 140 can be determined using these values at the center frequency f.₀, Gain G, and selectivity Q.

【0050】

Explaining the above setting procedure with the example of FIG. 15 (b), the frequency f at the peak position₀Is 280Hz, and the frequency of the intersection with the target level on both sides is f₁= 180Hz, f₂= 360Hz and the frequency ratio is R₁= 180/280 = 0.6429 R₂= 280/360 = 0.7778 And the larger R₂= 0.7778 is adopted. On the other hand, the difference between the target level and the peak position level is G = -7.0 dB, and 5.0 is adopted as the value of Q that gives the closest frequency ratio to 0.7778 under the level difference of -7.0 dB from Table 1. To do. From the above, the center frequency is set to 280Hz, the gain is set to -7.0dB, and Q is set to 5.0 as the characteristics of the parametric equalizer 140.

【0051】

(5) Simulation (S17) The frequency characteristic of the result of equalizing the measured frequency characteristic with the parametric equalizer 140 whose characteristics are set as described above is simulated in the CPU 158. That is, the frequency characteristics of the parametric equalizer 140 are converted into data in the CPU 158 and subtracted from the smoothed FFT data (Fig. 15 (b)) to predict the frequency characteristics after equalization. Then, if there is still a peak exceeding the target level on the frequency characteristics, the peak is calculated by the same procedure (S14 to S17) as above, and the characteristics of another band of the parametric equalizer 140 are set. By repeating the above, when there are no peaks that finally exceed the target level, the setting is completed (S18). The result of equalizing the characteristics of FIG. 15 (a) using the parametric equalizer 140 for which the setting has been completed is shown in FIG. 15 (c). According to FIG. 15 (c), all parts of the frequency characteristics are set to the target level of -1.5 dB or less, and howling can be prevented from occurring.

【0052】

The programmable equalizer 134 (PEQ2) in FIG. 1 is also composed of a parametric equalizer, and FFT measurement can be performed separately by the same method as in FIG. 14, and the characteristics can be set based on the result. When setting the parametric equalizer 134, turn on the switch SW1 in FIG. 13 to close the loop, leave the parametric equalizer 140 in the above-set state, and keep the other programmable equalizers 124 to 130 (PEQ1) flat. By the time the parametric equalizer 140 (PEQ3) is set up, the frequency response should be almost flat, but a whiskers-like peak remains. A parametric equalizer 134 is used to remove the whiskers one by one. Here, it is only necessary to remove the peak-shaped whiskers, and the Q of the parametric equalizer 134 is fixed at a certain sharp value (about 10.0) so that the other parts are not scraped off, and the center frequency f.₀And gain G are set based on the FFT measurement result.

【0053】

In addition, the programmable equalizers 124 to 130 (PEQ1) in Fig. 1 can also be configured with parametric equalizers, FFT measurements can be performed individually in the same manner as in Fig. 14, and the characteristics can be set individually based on the results. .. After the automatic adjustment of the characteristics of all equalizers PEQ1, PEQ2, and PEQ3 is completed as described above, the volume can be adjusted to the desired volume with the volume 172 and actually used.

【0054】

In the above embodiment, the number of speaker systems for one sound field control unit 62 is one, but a plurality of speaker systems can be provided. An example is shown in FIG. In the sound field control unit 156, the woofer 160 is arranged downward at the lower end of the housing 158, and the scoker 162 is arranged upward at the upper end. The sound reproduced from the woofer 160 is radiated to the outside through the opening 164 formed in the lower part of the housing 158. If a plurality of speaker units are provided in this way, the effect of further diffusing the sound can be obtained.

【0055】

[Effect of the invention]

As described above, according to the present invention, the introduction of the sound field support system is facilitated.

[Simple explanation of drawings]

[Figure 1]

It is a block diagram which shows the embodiment of the sound field control unit of this invention, and is the internal circuit diagram of the sound field control unit of FIG.

[Figure 2]

It is a principle diagram of acoustic feedback.

[Fig. 3]

It is a layout drawing which shows the conventional introduction example of acoustic feedback.

[Fig. 4]

It is a block diagram which shows the circuit structure of the system of FIG.

[Fig. 5]

It is an external view which shows the embodiment of the sound field control unit of this invention.

[Fig. 6]

It is an exploded view of the sound field control unit of FIG.

[Fig. 7]

It is a figure which shows the rear panel arranged on the back side of the sound field control unit of FIG.

[Fig. 8]

It is a figure which shows the embodiment of the sound field control apparatus of this invention, and is the layout drawing which shows the introduction example of the sound field control unit of FIG.

[Fig. 9]

It is a schematic diagram which shows the connection structure of the composite cable 108 of FIG.

[Fig. 10]

It is a figure which shows the operation example of the sound pickup signal switching circuit of FIG.

[Fig. 11]

It is a schematic diagram which shows the time axis fluctuation operation of the FIR filter of FIG.

[Fig. 12]

It is the flowchart of the automatic adjustment operation by the sound field control unit of FIG.

[Fig. 13]

It is a block diagram which shows the structure when the characteristic of the parametric equalizer 140 is automatically set when the programmable equalizer 140 of FIG. 1 is configured by a parametric equalizer.

[Fig. 14]

It is a flowchart which shows the automatic setting procedure of the characteristic of the parametric equalizer 140 by the structure of FIG.

[Fig. 15]

It is a frequency characteristic diagram which shows the specific example of the characteristic setting operation by the procedure of FIG.

[Fig. 16]

It is a partially enlarged view of the frequency characteristic explaining the procedure of steps S15 to S16 of FIG.

[Fig. 17]

It is an external view which shows the other embodiment of the sound field control unit of this invention.

[Explanation of symbols]

62 Sound field control unit 68 Circuit section unit (electric circuit section) 70 Amplifier unit (amplifier, electric circuit part) 72 Speaker system (speaker) 78 Microphone unit (microphone) 80 Front cover (side of housing) 90 Infrared light receiving window (infrared light receiving part) 94 housing 96 Top opening 100,102 terminals (sound collection signal input / output terminals) 108 Composite cable (transmission cable) 132 Sound collection signal switching circuit (sound collection signal switching means) 134 Equalizer (front side) 138 FIR filter 140 Equalizer (rear side) 142 Attenuator 150 infrared remote control transmitter 154 Reference signal generation circuit (reference signal generation means) 156 Measuring circuit (measuring means) 158 CPU 160 Sound field controller