JPH0787590A - Variable directivity speaker - Google Patents

Abstract

PURPOSE:To obtain a variable directivity speaker having sharp directivity even in a normal room. CONSTITUTION:The output of a signal source 1 is band-divided and branched by a low pass filter 6 and a high pass filter 7. After a signal level attenuater 8 sets the level of the branched signals and a mixer 9 mixes them, the signal is amplified by an amplifier 10 and inputted to a speaker unit 11. A microphone 2 collects direct and reflected waves radiated from a speaker array and the signal is band-divided by low and high pass filters 3, 4 and inputted to a level setting controller 5. The level setting controller 5 receives the band-divided signal of each microphone and detects sound pressure distribution in the room in each frequency band to set the signal level attenuater 8 so as to obtain desired sound pressure distribution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker device capable of controlling directivity.

[0002]

2. Description of the Related Art When a general speaker system is used when different explanations are made at adjacent booths at an exhibition hall or when different announcements are made at adjacent platforms at stations, the sounds from each speaker are mixed, which is very difficult. It may be difficult to hear. This is because a normal speaker system is designed so that sound is reproduced in the same way in any direction, that is, it has wide directivity. In such a case, in order to make it easier to hear individual voices, there is a demand for a speaker system having a sharp directivity so that a strong sound pressure can be obtained only in a specific place.

Conventionally, as one means for realizing a narrow directivity of sound, a speaker array is constructed by arranging a plurality of speaker units in a linear shape or a plane shape, and a signal input to each speaker unit is controlled. It is known how to do it. The configuration will be described below with reference to FIGS. 8 to 12.

FIG. 8 is a block diagram showing a directional speaker device disclosed in, for example, Japanese Unexamined Patent Publication No. 2-239798. In the figure, 1 is a signal source and 17 is an A / D as constituent elements.
Converter, 18 is FIR filter, 19 is D / A converter,
Reference numeral 10 is an amplifier, and 101 is a speaker array in which a plurality of speaker units 11 are linearly arranged.

The relationship and operation of these constituent elements will be described. The output of the signal source 1 is A / D converted and then branched into a plurality of pieces, and the FIR filter 18 controls the phase and amplitude characteristics. Further, after being D / A converted, it is amplified by the amplifier 10, and the same signal is input to the pair of speaker units 11 located symmetrically with respect to the symmetry axis of the speaker array 101.

By controlling the phase / amplitude characteristics of the signal input to each speaker unit 11 constituting the speaker array 101, the directivity can be sharpened or widened, or the direction of the directivity can be changed. It is well known that (direction axis deflection) and the like are possible.

FIG. 9 shows a directional speaker device including a speaker array 107 in which speaker units 11 (12 pieces) having a diameter of 9.4 cm are arranged in a grid pattern at intervals of 25 cm, a signal source 1 and an amplifier 10.

FIG. 10 shows a sound pressure distribution in an anechoic chamber when all speaker units constituting this speaker array are driven in phase and at the same level. That is, it is a distance of 1.5 m from the speaker array, and an equal sound pressure line is displayed in a plane parallel to the speaker array, and the interval of the equal sound pressure line is every 3 dB. The point where the horizontal axis coordinate is 1 m and the vertical axis coordinate is 1.5 m is directly under the center of the speaker array, and the sound pressure is highest. Note that FIG.
Then, the sound pressure level at this point is standardized and displayed at 0 dB.

Further, FIG. 11 shows a case where the directional speaker device of FIG. 9 is mounted 1.5 m below the speaker array when the directional speaker device is mounted on a ceiling of a room having a length of 3.8 m × width of 6.8 m × height of 3.0 m. The sound pressure distribution in the horizontal plane is shown as in FIG.

[0010]

However, the conventional directional speaker device as described above has the following problems. Comparing FIG. 10 and FIG. 11, it can be seen that even with the same speaker device, the directivity in the anechoic room and the directivity in the actual room are significantly different. Generally, even in a speaker device which can obtain a considerably sharp directivity in an anechoic room, when the speaker device is installed and used in an actual room, a high sound pressure level range is considerably widened. For example, 50
At 0 Hz, the sound pressure level at a point 2 m away from the point with the highest sound pressure is -28 dB in FIG. 10, whereas in FIG.
In No. 1, it is only -9 dB.

FIG. 12 schematically shows the reason for this. Since the wall surface in the anechoic chamber does not reflect sound, when the sound source has a sharp directivity, a strong sound pressure can be obtained by concentrating in a narrow range. Compared to that, the wall surface in the actual room reflects sound,
The sound pressure levels in the room are averaged to spread the sound waves,
It is difficult to limit the range where strong sound pressure can be obtained.

In order to solve this, it is necessary to control the phase / amplitude characteristic of the signal input to each speaker unit constituting the speaker array after considering the reflected wave from the wall surface in advance. However, since the positional relationship between the speaker and the wall surface in the room and the sound absorption coefficient in the room are different from each other, when the configuration shown in FIG. 8 is taken, the optimum control method is calculated for each room in which the speaker is installed. It is necessary to change the filter characteristic every time, and there is a problem of lacking versatility.

The present invention solves the above-mentioned problems and provides a sharp directivity even when a directional speaker device is used in an actual room having a reflected wave, and further relates to a place where the speaker device is used. The purpose is to obtain sharp directivity.

[0014]

In order to achieve the above-mentioned object, a directional control speaker device of the present invention includes a speaker array comprising a plurality of speaker units arranged in a linear or planar shape, and a linear or A microphone array including a plurality of microphones arranged in a plane, a plurality of signal adjusting means for adjusting an input signal to the plurality of speaker units, and an output signal from the plurality of microphones , And a control means for controlling the signal adjusting means based on this.

[0015]

In the directional control speaker device having the above structure,
The sound wave radiated from the speaker array reaches each microphone as a direct wave or a reflected wave from the wall surface / floor surface / ceiling surface. The control means first takes in the output signal from each microphone and detects the state of the sound pressure distribution in the room. Then, based on this, a control method of the signal adjusting means is obtained so that a desired sound pressure distribution is obtained, and the signal adjusting means is controlled by this.

Through such a process, the phase / amplitude characteristic of the signal input to each speaker unit is controlled in consideration of the reflected wave from the wall surface, and the sharp directivity is achieved regardless of where the speaker device is used. It becomes possible to obtain the sex.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments. FIG. 1 is a block diagram of a directivity control speaker device of a first embodiment according to the present invention. Explaining the relationship and operation of each constituent element shown in the figure, the output of the signal source 1 is first a low pass filter 6 and a high pass filter 7.
The band is divided by and is branched for each speaker unit (or a set of speaker units) to be controlled. The level of the branched signal is set by the signal level attenuator 8. The signal whose level is set for each band is mixed for each speaker unit (set) to be controlled by the mixer 9, and then is amplified by the amplifier 10 to be supplied to each speaker unit 11 in the speaker array 101.
Entered in. The signal adjusting means 104 is composed of the low-pass filter 6 and the high-pass filter 7, the signal level attenuator 8, the mixer 9, and the amplifier 10 as a whole.

The microphone 2 is a speaker array 101.
It collects the direct waves radiated from and the reflected waves from the wall surface and converts them into electrical signals. Signal is low pass filter 3
The signal is band-divided by the high-pass filter 4 and input to the level setter control device 5. The control means 103
It comprises a low-pass filter 3, a high-pass filter 4, and a level setter control device 5.

The level setting device control device 5 receives the band-divided signals of the microphones 2 and detects the sound pressure distribution in the room in each frequency band. Further, the signal level attenuator 8 is set so as to obtain a desired sound pressure distribution based on the detected sound pressure distribution.

FIG. 2 shows an example in which the directional control speaker device of this embodiment is used indoors. The speaker array 101 is mounted on the ceiling, and the microphone arrays are two-dimensionally arranged on the floor to detect the sound pressure distribution in the room.

With such a configuration, the level of the signal input to each speaker unit is controlled in each frequency band in consideration of the reflected wave from the wall surface, and the sharp directivity is obtained irrespective of the place where the speaker device is used. Can be obtained.

In the above embodiment, the case where the signal is divided into two bands by the low-pass filter and the high-pass filter has been described. However, the present invention is not limited to this, and when the signal is divided into three or more bands, more detailed It becomes possible to control. Further, the arrangement of the speaker unit and the microphone is not limited to the illustrated arrangement.

Next, a directivity control speaker device according to a second embodiment of the present invention will be described with reference to FIG.
FIG. 3 is a block diagram of the directivity control speaker device of this embodiment. In FIG. 3, the speaker array 101, the microphone array 102, and the signal adjusting means 104 have the same configurations as those in the first embodiment.

The microphone 2 collects direct and reflected waves and converts them into electric signals. The signal is band-divided by the low-pass filter 3 and the high-pass filter 4, and the voltmeter 1
2 measures the voltage of the band-divided signal (that is, the sound pressure value for each band at the position of the microphone) and sends the measured value to the calculation device 13. The calculation device 13 performs the following calculation, calculates the setting value of the signal level attenuator 8 in each frequency band, sets the signal level attenuator 8 and stores the setting value in the storage device 14.

The i-th microphone (i = 1, ...
., M) is Pi, and the sound pressure value preset for each microphone is Ti. Further, the set value of the j-th signal level setting device (j = 1, ... N) in the k-th step is Xj (k). Although the square of the difference between Pi and Ti is multiplied by a predetermined weighting factor Wi, the total sum E for i is expressed by (Equation 1). Here, E is a function of Xj (k). Here, the setting value Xj (k-1) of the j-th signal level setter at the previous step k-1 times is stored in the storage device 14. Therefore, a new set value Xj (k + 1) can be calculated with reference to this so that E becomes smaller. This includes
For example, a quasi-Newton method algorithm may be used.

By repeating this step, the set value Xj of the signal level setter converges, the value of E gradually decreases, and the actual sound pressure value in each frequency band approaches the set value. Therefore, if the set sound pressure value Ti at the position of the microphone is set so that a strong sound pressure is obtained only in a specific place, sharp directivity can be obtained even in an actual room.

Instead of (Equation 1), the actual sound pressure expressed by (Equation 2) is Pi, and the set sound pressure value is Ti.
The same applies to the sum E of i obtained by multiplying the absolute value of the difference between Pi and Ti by a predetermined weighting factor Wi. This is expressed as in (Equation 2). Although the voltmeter is used to read the output level of the filter in the present embodiment, the present invention is not limited to this, and the arithmetic unit configured to perform the above-described calculation according to the output level of each filter is configured. Just do it.

Next, a directivity control speaker device according to a third embodiment of the present invention will be described with reference to FIG.
FIG. 4 is a block diagram of the directivity control speaker device of the third embodiment. The output of the signal source 1 is converted into a digital signal by the A / D converter 17, and is branched for each speaker unit (or a set of speaker units) to be controlled. The branched signal is controlled by the FIR filter 18, converted into an analog signal by the D / A converter 19, amplified by the amplifier 10, and input to each speaker unit 11. The signal adjusting means 104 is composed of the A / D converter 17, the FIR filter 18, the D / A converter 19, and the amplifier 10 as a whole.

The microphone 2 is a speaker array 101.
It collects the direct waves radiated from and the reflected waves from the wall surface and converts them into electrical signals. The signal is converted into a digital signal by the A / D converter 15 and input to the FIR filter controller 16. The control means 103 comprises an A / D converter 15 and a FIR filter control device 16.

The FIR filter controller 16 receives the signals converted into digital signals from the microphones and detects the sound pressure distribution in the room in each frequency band. Further, the coefficient of the FIR filter 18 is set so that a desired sound pressure distribution can be obtained based on the detected sound pressure distribution.

In the above-mentioned structure, the control means and the signal adjusting means are
In particular, except that digital signal processing is used, the configuration is the same as that of the first embodiment, and it is possible to obtain a sharp directivity regardless of where the speaker device is used.

Next, a directivity control speaker device according to a fourth embodiment of the present invention will be described with reference to FIG.
FIG. 5 is a block diagram of the directivity control speaker device of the fourth embodiment. In FIG. 5, a speaker array 101, a microphone array 102, and a signal adjusting means 104.
Has the same configuration as that of the third embodiment.

The microphone 2 collects direct and reflected waves and converts them into electric signals. After the signal is A / D converted, F
The frequency analysis is performed by the FT device 20, and the result is sent to the calculation device 21. The calculation device 21 performs the same calculation as the calculation device 13 in the second embodiment, and calculates the transfer function of the FIR filter 18. The calculation result is the inverse F
The transfer function value is sent to the FT device 23 and the transfer function value is stored in the storage device 2
Save to 2. The inverse FFT device 23 calculates the FI from the transfer function value.
The coefficient value of the R filter 18 is calculated and the FIR filter 18 is set.

In the above-mentioned structure, the control means and the signal adjusting means are
In particular, except that the digital signal processing is used, the configuration is the same as that of the second embodiment, and it is possible to obtain a sharp directivity regardless of the place where the speaker device is used. Furthermore, by using digital signal processing, even a filter that cannot be realized by analog signal processing can be easily configured, so that precise and accurate control can be performed at each frequency.

Finally, a directivity control speaker device according to a fifth embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG. 6 is a block diagram of the directivity control speaker device of the fifth embodiment. In FIG. 6, a speaker array 101, a microphone array 102, and a control means 10
3 and the signal adjusting means 104 have the same configuration as in the first embodiment. Between the speaker array 101 and the microphone array 102, a detection device 107 that detects the presence or absence of listeners in the service area is installed.

The detector 107 comprises an infrared source and its receiver. When the listener stands between the infrared source and the receiver,
The infrared light is blocked and the receiver detects the presence of the listener.
FIG. 7 shows an example in which the directional control speaker device of this embodiment is used indoors. The speaker array 101 is attached to the ceiling, and the microphone arrays are two-dimensionally arranged on the floor surface to detect the sound pressure distribution in the room. Further, the detection device 107 is installed on the wall surface.

When the detection device 107 detects the presence of a listener in the service area, the level setting device control device changes the control method of the signal adjusting means 104. For example, when using a plurality of directivity control speaker devices, if the listener is present, the directivity is sharpened to increase the volume, and if the listener is not present, the directivity is widened to lower the volume. Is effective.

In this embodiment, an infrared source and its receiving device are used as the detecting device, but the detecting device is not limited to this. For example,
Similar effects can be obtained even when an internal monitoring camera, a pyroelectric sensor, or an ultrasonic sensor is used as the detection device.

[0039]

As is apparent from the above description of each embodiment, the present invention can obtain sharp directivity even when the directivity control speaker device is used in an actual room having a reflected wave, and further the speaker device is used. A sharp directivity can be obtained regardless of where the is used.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a directional control speaker device according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing an arrangement of the directivity control speaker device.

FIG. 3 is a block diagram showing a configuration of a directional control speaker device according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a directional control speaker device according to a third embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a directional control speaker device according to a fourth embodiment of the present invention.

FIG. 6 is a block diagram showing the configuration of a directional control speaker device according to a fifth embodiment of the present invention.

FIG. 7 is a perspective view showing an arrangement of the directivity control speaker device.

FIG. 8 is a block diagram showing a configuration of a directional speaker device of a first conventional example.

FIG. 9 is a diagram showing a configuration of a directional speaker device of a second conventional example.

FIG. 10 is a diagram showing sound pressure distribution in an anechoic chamber of the directional speaker device of FIG. 9.

11 is a diagram showing a sound pressure distribution in the room of the directional speaker device of FIG. 9.

FIG. 12 is a diagram showing an operation of the directional speaker device of FIG. 9.

[Explanation of symbols]

 1 signal source 2 microphone 3 low pass filter 4 high pass filter 5 level setting device control device 6 low pass filter 7 high pass filter 8 signal level attenuator 9 mixer 10 amplifier 11 speaker unit 101 speaker array 102 microphone array 103 control means 104 signal adjusting means

Claims (6)

[Claims] 1. A speaker array including a plurality of speaker units arranged in a line or a plane, a microphone array including a plurality of microphones arranged in a line or a plane, and the plurality of speaker units. A signal adjusting means for adjusting an input signal to the device, and a control means for controlling the signal adjusting means on the basis of the output signals from the plurality of microphones, wherein the signal adjusting means is A plurality of filters (A) for dividing a frequency band, a plurality of signal level attenuators cascaded in each of the filters (A), and a mixer for mixing signals from the signal level attenuators, The control means is connected to each of the plurality of microphones and divides the frequency band of the output signal from the microphone. A directional control speaker device, wherein the signal level attenuator is controlled according to the output voltage value of the filter (B). 2. The control means comprises a plurality of filters (B) for dividing the frequency band of the output signal from the microphone,
The filter (B) is connected to an arithmetic unit, the arithmetic unit calculating a control value of the signal level attenuator according to the output value of each filter, and temporarily storing the calculation result of the calculator. The calculation device, in each of the divided frequency bands, the absolute value or the square of the difference between the sound pressure value preset for the position of the microphone and the actual sound pressure value,
To calculate the sum of those multiplied by a predetermined coefficient, update the control value of the signal level attenuator so as to minimize the sum by referring to the value stored in the storage device, and control repeatedly. The directional control speaker device according to claim 1, which is characterized in that. 3. A speaker array including a plurality of speaker units arranged in a line or a plane, a microphone array including a plurality of microphones arranged in a line or a plane, and the plurality of speaker units. A signal adjusting means for adjusting an input signal to the plurality of microphones, and a control means for controlling the signal adjusting means based on the output signals from the plurality of microphones. D converter and a plurality of F
An IR filter and a plurality of D / A converters connected in series to the IR filter, wherein the control means is configured to operate in accordance with output values of the plurality of A / D converters connected in series to the plurality of microphones. A directivity control speaker device characterized by controlling a coefficient of an FIR filter. 4. The control means comprises an A / D converter cascaded to a microphone and an arithmetic unit, and the arithmetic unit comprises a plurality of FFT units cascaded to the respective A / D converters, and the FFT. A calculation device for calculating a predetermined function value from the conversion result of the device; a storage device for temporarily storing the calculation result of the calculation device; and a plurality of inverse FFT devices connected to the calculation device. , The preset value and the actual FF for each of the FFT devices at each frequency.
The absolute value or the square of the difference from the conversion result of the T device is multiplied by a predetermined coefficient to obtain a total sum, and the transfer function value of the FIR filter stored in the storage device is referred to to minimize the total sum. The transfer function value of the FIR filter is updated so that the inverse FFT device obtains the coefficient of the FIR filter from the transfer function value of the FIR filter at each frequency, and repeatedly controls the FIR filter. The directional control speaker device according to claim 3. 5. A speaker array including a plurality of speaker units arranged in a line or a plane, a microphone array including a plurality of microphones arranged in a line or a plane, and the plurality of speaker units. Signal adjusting means for adjusting an input signal to the plurality of microphones, control means for controlling the signal adjusting means on the basis of the output signals from the plurality of microphones, and a listener in a preset service area. A directional control speaker device comprising a detection device for detecting the presence or absence, and changing the control method of the signal adjusting means when the presence of a listener is detected. 6. The directional control speaker device according to claim 5, wherein the detection device is one of an infrared sensor, a pyroelectric sensor, a surveillance camera, and an ultrasonic sensor.