JP3186181B2 - Howling suppression device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a howling suppressing device for preventing howling between a microphone and a speaker.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing an example of a conventional howling suppressing device. In FIG. 4, reference numeral 1 denotes a microphone for collecting performances and sounds in the hall, 2 denotes a microphone amplifier, 3 denotes a volume, 4 denotes howling suppressing means, 5 denotes a power amplifier,
6 is a speaker, 7 is a volume control circuit, 8 is a howling detection circuit, and 9 is a filter selection circuit.

[0003] The operation of the conventional howling suppressing device configured as described above will be described below.

A signal collected from a microphone 1 is amplified by a microphone amplifier 2 and input to a volume 3. The volume 3 varies the level of an audio signal to be output according to a control signal from the volume control circuit 7. Volume 3 with silence
By increasing the level step by step, the loop gain of the reproduction system increases, and if it exceeds 1, howling occurs. The signal that has passed through the volume 3 is filtered by the howling suppression means 4 and is amplified by the power amplifier 5 and the speaker 6. The howling suppression means 4 sets a filter for suppressing howling according to the control signal from the filter selection circuit 9.

On the other hand, the signal that has passed through the volume 3 is also input to a howling detection circuit 8. The howling detection circuit 8 detects the occurrence of howling and howling frequency, and outputs the presence or absence of howling to the volume control circuit 7 and outputs the howling frequency to the filter selection circuit 9, respectively.
The volume control circuit 7 controls the volume of the volume 3 to gradually increase from the minimum level until the occurrence of the howling is confirmed by the howling occurrence detection signal, and returns to the initial value when the howling is detected. Further, the filter selecting circuit 9 controls the howling suppression means so as to have a filter characteristic of attenuating the frequency in accordance with the howling detection frequency signal, thereby suppressing the first howling point. The above operation is repeated to suppress a plurality of howling points. As described above, it is possible to improve the howling margin by previously reducing the level of the frequency at which howling is likely to occur.

[0006]

However, in the above-described configuration, the effect of improving the loudspeaker gain by setting the filter cannot be clearly known. In order to confirm the effect, the filter is switched on and off and the difference in howling margin is reduced. Requires operations such as viewing.

Further, it is inevitable that sound quality is deteriorated due to the filter setting, and the operator cannot know even if the gain improvement effect by the filter setting is small, and the sound quality is deteriorated by setting many filters. There is a disadvantage that.

[0008] Similarly, even when the gain improvement effect is small, the howling suppression apparatus has a drawback that the sound quality is degraded by setting a filter.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a howling suppressing apparatus capable of easily knowing a gain improving effect by setting a filter and performing effective howling suppression while suppressing sound quality deterioration. .

[0010]

In order to achieve the above object, the present invention provides, as a first invention, a volume for varying an audio signal level, and a howling detection circuit for detecting howling from the varied audio signal. A filter selection circuit for setting a filter for suppressing the howling, a howling suppression means for applying the filter to the output signal of the volume, a volume control circuit for controlling the volume by a signal from the howling detection circuit, and a volume control A state of the circuit and a state of the howling suppressing means are sequentially stored, and a level difference discriminating circuit for discriminating a howling level difference from the stored information and a display means for displaying a result of the level difference discriminating circuit are provided.

According to a second aspect of the present invention, a volume for varying an audio signal level, a howling detection circuit for detecting howling from the varied audio signal, a filter selection circuit for setting a filter for suppressing the howling, Howling suppression means for applying the filter to the output signal of the volume, a volume control circuit for controlling the volume by a signal from the howling detection circuit, and a state of the volume control circuit and a state of the howling suppression means are sequentially stored. A level difference discriminating circuit for discriminating a howling level difference from the stored information, an improvement effect judging circuit for comparing a result of the level difference discriminating circuit with a predetermined set value, and a result of the improvement effect judging circuit. Is displayed by the display means.

According to a third aspect of the present invention, a volume for varying an audio signal level, a howling detection circuit for detecting howling from the varied audio signal, a filter selection circuit for setting a filter for suppressing the howling, Howling suppression means for applying the filter to the output signal of the volume, a volume control circuit for controlling the volume by a signal from the howling detection circuit, and a state of the volume control circuit and a state of the howling suppression means are sequentially stored. A level difference discriminating circuit for discriminating a howling level difference from the stored information, an improvement effect judging circuit for comparing a result of the level difference discriminating circuit with a predetermined set value, and a result of the improvement effect judging circuit. Signal to the filter selection circuit and volume control circuit. It constituted by forcible termination control circuit for sending a.

[0013]

With this configuration, the gain improvement effect by the filter setting can be known from the level difference between the volume level when the howling suppressed by the filter is detected and the filter level after the howling is detected. By displaying the result, the operator can be notified of the gain improvement effect. In addition, by displaying the gain improvement effect in magnitude, the warning can be given to the sound quality deterioration due to careless filter setting. In addition, when the gain improvement effect is small, the setting of the corresponding filter is canceled and the howling suppressing operation is terminated, so that it is possible to prevent sound quality deterioration due to unnecessary filter setting.

[0014]

(Embodiment 1) Hereinafter, a howling suppressing apparatus according to a first embodiment will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a microphone for collecting performances and sounds in the hall, 2 denotes a microphone amplifier, 3 denotes a volume, 4 denotes howling suppressing means, 5 denotes a power amplifier, 6 denotes a speaker, 7 denotes a volume control circuit, 8 Is a howling detection circuit, 9 is a filter selection circuit, 10 is a level difference determination circuit,
Reference numeral 11 denotes a display unit.

The operation of the howling suppression device configured as described above will be described below.

A signal collected from the microphone 1 is amplified by the microphone amplifier 2 and input to the volume 3. The volume 3 varies the level of an audio signal to be output according to a control signal from the volume control circuit 7. Volume 3 with silence
By increasing the level step by step, the loop gain of the reproduction system increases, and if it exceeds 1, howling occurs. The signal that has passed through the volume 3 is filtered by the howling suppression means 4 and is amplified by the power amplifier 5 and the speaker 6. The howling suppression means 4 sets a filter for suppressing howling according to the control signal from the filter selection circuit 9. On the other hand, the signal that has passed through the volume 3 is also input to the howling detection circuit 8. The howling detection circuit 8 detects the occurrence of howling and howling frequency, and outputs the presence or absence of howling to the volume control circuit 7 and outputs the howling frequency to the filter selection circuit 9, respectively. The volume control circuit 7 controls the volume of the volume 3 to gradually increase from the minimum level until the occurrence of the howling is confirmed by the howling occurrence detection signal, and returns to the initial value when the howling is detected. The filter selection circuit 9 suppresses c c ring point controls the anti-feedback means so Motas filter characteristics for attenuating the corresponding frequency according to the howling detection frequency signal. In this embodiment, a notch filter is used as a filter. Fill from the volume control circuit 7
The level of volume 3 is judged to be level difference with no data inserted
It is input to another circuit 10 level difference determination circuit 10 volumes
The peak value of level 3 is stored as the first howling detection level. Further, the filter selection circuit 9
By controlling the ring suppression means 4 and inserting the first filter,
Suppress one howling point . With the first filter inserted, the volume control circuit 7 raises the volume 3 to a level at which the next howling occurs .
The level difference determination circuit 10 determines the level peak of the volume 3.
When the peak value is stored as the second howling detection level
Both are stored in the first howling detection level
Stored as the peak value and the second howling detection level
The level difference, which is the difference from the peak value, is determined, and the result is output to the display unit 11. Also, the filter selection circuit 9
Controls the howling suppression means 4 and activates the second filter
And suppress the second howling point. The display means 11 has determined the gain improvement effect of the first filter .
Displays the level difference . The display means 11 uses, for example, a 7-segment LED. The above operation is repeated to suppress a plurality of howling points, and the gain improvement value of each filter is displayed.

As described above, according to the present embodiment, the volume control circuit 7 for generating the howling, the howling detection circuit 8 for detecting the occurrence of the howling and the frequency, and the control progress of the volume control circuit 7 before and after setting each filter. A level difference discriminating circuit 10 for discriminating a level difference for detecting howling and a display means 11 for displaying the discriminated level difference as a gain improvement effect by setting a filter. The operator can be immediately notified of the gain improvement effect of the above operation with some operation.

Further, it is possible to notify the gain improvement effect of the entire howling suppression apparatus by adding and displaying the discrimination values of the respective filters.

(Embodiment 2) Hereinafter, a howling suppressing apparatus according to a second embodiment will be described with reference to the drawings.

In FIG. 2, the same part numbers as those in FIG. 1 indicate the same names and the same operations, and a description thereof will be omitted.
12 is an improvement effect determination circuit, and 13 is a display means.

The operation of the howling suppression device configured as described above will be described below.

The determination result from the level difference determination circuit 10 is input to the improvement effect determination circuit 12. The improvement effect determination circuit 12 compares the determined gain improvement effect with a preset set value of the desired gain improvement effect, determines the magnitude of the gain improvement effect by the filter setting, and outputs the result to the display unit 13.
The display means 13 displays a warning when the gain improvement effect is small according to the result. The display unit 13 uses, for example, an LED.

As described above, according to this embodiment, the volume control circuit 7 for generating the howling, the howling detection circuit 8 for detecting the occurrence of the howling and the frequency, and the control progress of the volume control circuit 7 before and after setting each filter. , A level difference discriminating circuit 10 for discriminating a level difference for detecting howling, and an improvement effect judging circuit for comparing a result of the level difference discriminating circuit 10 with a preset gain improvement setting value to determine a gain improvement effect of the filter. 12 and a display means 13 for displaying a warning when the judgment result indicates that the improvement effect is small, so that the operator can immediately know the magnitude of the gain improvement effect of the filter set for suppressing howling with some operation and immediately. In other words, a warning can be given to sound quality deterioration due to careless filter setting.

(Embodiment 3) Hereinafter, a howling suppressing apparatus according to a third embodiment will be described with reference to the drawings.

In FIG. 3, the same part numbers as those in FIG. 1 indicate the same names and the same operations, and a description thereof will be omitted.
Also, the same part numbers as those in FIG. 2 indicate the same operations with the same names, and the description thereof will be omitted. 14 is a forced termination control circuit.

The operation of the howling suppression device configured as described above will be described below.

The determination result of the improvement effect determination circuit 12 is output to the forced termination control circuit 14. The forced termination control circuit 14 transmits a termination command to the volume control circuit 7 and the filter selection circuit 9 when the gain improvement effect is small according to the input determination result, and the volume control circuit 7
Is returned to the initial value, and the filter selection circuit 9 causes the forced termination so as to cancel the setting of only the corresponding filter. Therefore, setting of a filter having a small effect is automatically avoided.

As described above, according to the present embodiment, the volume control circuit 7 for generating howling, the howling detection circuit 8 for detecting the occurrence and frequency of howling, and the control progress of the volume control circuit before and after setting each filter. A level difference discriminating circuit 10 for discriminating a level difference for detecting howling, and an improvement effect judging circuit 12 for comparing a result of the level difference discriminating circuit 10 with a preset gain improvement set value to determine a gain improvement effect of the filter. And a forced termination control circuit 14 for prohibiting the setting of the corresponding filter when the determination result indicates that the improvement effect is small, and terminating the howling suppression operation. And howling can be effectively suppressed.

[0030]

As described above, a volume for varying the audio signal level, a howling detection circuit for detecting howling from the varied audio signal, a filter selection circuit for setting a filter for suppressing the howling, and a filter for the volume. Howling suppression means for applying the filter to the output signal; a volume control circuit for controlling the volume by a signal from the howling detection circuit; and a howling level difference from the state of the volume control circuit and the state of the howling suppression means. By providing a level difference discriminating circuit for discriminating and a display means for displaying a result of the level difference discriminating circuit, a level between a volume level at which the howling suppressed by the filter is detected and a volume level at which the howling occurs after the filter is set. From the difference,
The gain improvement effect by the filter setting can be known, and the result is displayed to inform the operator of the value of the gain improvement effect.

Also, a volume for varying the audio signal level, a howling detection circuit for detecting howling from the varied audio signal, a filter selection circuit for setting a filter for suppressing the howling, and an output signal of the volume Howling suppression means for applying a filter, a volume control circuit for controlling the volume by a signal from the howling detection circuit, and a level difference for determining a howling level difference from the state of the volume control circuit and the state of the howling suppression means. A discriminating circuit; an improvement effect judging circuit for judging a result of the level difference discriminating circuit and a predetermined set value; and a display means for displaying a result of the improving effect judging circuit. Can be displayed by judging the size of Those having an effect becomes possible to give a warning to sound quality degradation by a constant.

Also, a volume for varying the audio signal level, a howling detection circuit for detecting howling from the varied audio signal, a filter selection circuit for setting a filter for suppressing the howling, and an output signal of the volume Howling suppression means for applying a filter, a volume control circuit for controlling the volume by a signal from the howling detection circuit, and a level difference for determining a howling level difference from the state of the volume control circuit and the state of the howling suppression means. A discrimination circuit, an improvement effect determination circuit for comparing the result of the level difference determination circuit with a predetermined set value, and a forced termination signal to the filter selection circuit and the volume control circuit based on the result of the improvement effect determination circuit. And a forced termination control circuit for sending Ri, can exit the unset howling suppressing operation of the filter if applicable gain improvement effect is small, an effect which can prevent quality degradation due to excessive filter settings.

[Brief description of the drawings]

FIG. 1 is a block diagram of a howling suppression device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a howling suppression device according to a second embodiment of the present invention.

FIG. 3 is a block diagram of a howling suppression device according to a third embodiment of the present invention.

FIG. 4 is a block diagram of a conventional howling suppression device.

[Explanation of symbols]

 Reference Signs List 1 microphone 2 microphone amplifier 3 volume 4 howling suppression means 5 power amplifier 6 speaker 7 volume control circuit 8 howling detection circuit 9 filter selection circuit 10 level difference determination circuit 11 display means 12 improvement effect determination circuit 13 display means 14 forced termination control circuit

Claims (3)

(57) [Claims] And 1. A volume of varying the audio signal level, a howling detection circuit for detecting a howling from the variable audio signals, and a filter selection circuit for setting a filter to suppress the howling, the output signal of the volume Means for suppressing howling,
And volume control circuit for controlling the volume by a signal from the howling detection circuit, the stored peak
Of any peak value and the peak value
A howling suppressing apparatus comprising: a level difference discriminating circuit for discriminating a level difference of howling from a previous peak value; and a display means for displaying a result of the level difference discriminating circuit. 2. A volume for varying the audio signal level, a howling detection circuit for detecting a howling from the variable audio signals, and a filter selection circuit for setting a filter to suppress the howling, the output signal of the volume Means for suppressing howling,
And volume control circuit for controlling the volume by a signal from the howling detecting circuit, the volume
Variable, sequentially storing peak values when howling occurs sequentially, and any peak value among the stored peak values.
A level difference discriminating circuit for discriminating a level difference of howling from the peak value immediately before the arbitrary peak value, and an improvement effect judging circuit for comparing a result of the level difference discriminating circuit with a predetermined set value. And a display means for displaying the result of the improvement effect determination circuit. 3. A volume of varying the audio signal level, a howling detection circuit for detecting a howling from the variable audio signals, and a filter selection circuit for setting a filter to suppress the howling, the output signal of the volume Means for suppressing howling,
And volume control circuit which controls the volume <br/> beam by a signal from the howling detecting circuit, the volume
Variable, sequentially storing peak values when howling occurs sequentially, and any peak value among the stored peak values.
A level difference discriminating circuit for discriminating a level difference of howling from the peak value immediately before the arbitrary peak value, and an improvement effect judging circuit for comparing a result of the level difference discriminating circuit with a predetermined set value. A howling suppression apparatus comprising: a forced termination control circuit for transmitting a forced termination signal to the filter selection circuit and the volume control circuit based on the result of the improvement effect determination circuit.