JPH05268120A - Howling suppression equipment - Google Patents

Abstract

PURPOSE:To reduce deterioration in sound quality by storing sequentially a state of a volume control circuit and a state of howling control means so as to discriminate a level difference of howling. CONSTITUTION:The equipment is provided with a volume control circuit 7 to generate howling, a howling detection circuit 8 detecting the occurrence of howling and its frequency, a level difference discrimination circuit 10 discriminating a level difference used to detect the occurrence of howling before and after the filter setting from the volume control circuit 7, and a display means 11 displaying a discriminated level difference as a gain improvement effect by the filter setting. Thus, the gain improvement effect by the filter setting is recognized based on a difference between a volume level when howling suppressed by the filter and a volume level when howling is detected after filter setting, and the gain improvement effect is informed to the operator by displaying the result.

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, 1 is a microphone for collecting performances and voices in the venue, 2 is a microphone amplifier, 3 is a volume, 4 is howling suppressing means, 5 is a power amplifier,
Reference numeral 6 is a speaker, 7 is a volume control circuit, 8 is a howling detection circuit, and 9 is a filter selection circuit.

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

A signal picked up from the microphone 1 is amplified by the microphone amplifier 2 and input to the volume 3. The volume 3 changes the audio signal level to be output according to the control signal from the volume control circuit 7. Volume 3 with no sound
By gradually increasing the level of, the loop gain of the reproducing system becomes large, and howling occurs when it exceeds 1. The signal that has passed through the volume 3 is filtered by the howling suppressing means 4 and is amplified by the power amplifier 5 and the speaker 6. The howling control means 4 sets a filter for suppressing howling according to a 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 howling and howling frequency, and outputs the presence or absence of howling to the volume control circuit 7 and the howling frequency to the filter selection circuit 9, respectively.
The volume control circuit 7 controls the level of the volume 3 stepwise from the minimum level until the howling occurrence is confirmed by the howling occurrence detection signal, and when the howling is detected, the volume control circuit 7 returns to the initial value. Further, the filter selection circuit 9 controls the howling suppressing means so as to have a filter characteristic of attenuating the corresponding frequency according to the howling detection frequency signal, and suppresses the first howling point. The above operation is repeated to suppress a plurality of howling points. In this way, the howling margin can be improved by reducing the level of the frequency at which howling is likely to occur in advance.

[0006]

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

In addition, it is inevitable that the sound quality will be deteriorated by the filter setting, and even if the gain improving effect by the filter setting is small, the operator cannot know, and the sound quality is deteriorated by setting many filters. There is a drawback.

Similarly, even when the gain improving effect is small, the howling suppressing apparatus has a drawback that a sound quality is deteriorated by setting a filter.

In view of the above problems, it is an object of the present invention to provide a howling suppressing device which can easily know the gain improving effect by the filter setting and can effectively suppress howling 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 a voice signal level, and a howling detection circuit for detecting howling from the varied voice signal. A filter selection circuit for setting a filter for suppressing the howling, a howling suppressing 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 level difference discriminating circuit for sequentially storing the state of the circuit and the state of the howling suppressing means and discriminating the level difference of howling from the stored information, and a display means for displaying the result of the level difference discriminating circuit.

According to a second aspect of the present invention, a volume for varying a voice signal level, a howling detection circuit for detecting howling from the varied voice signal, a filter selecting circuit for setting a filter for suppressing the howling, A howling suppressing 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, a state of the volume control circuit and a state of the howling suppressing means are sequentially stored. , A level difference discrimination circuit for discriminating a howling level difference from the stored information, an improvement effect determination circuit for comparing the result of the level difference determination circuit with a predetermined set value, and a result of the improvement effect determination circuit It is composed of display means for displaying.

As a third aspect of the invention, a volume for varying the audio signal level, a howling detection circuit for detecting howling from the varied audio signal, a filter selecting circuit for setting a filter for suppressing the howling, A howling suppressing 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, a state of the volume control circuit and a state of the howling suppressing means are sequentially stored. , A level difference discrimination circuit for discriminating a howling level difference from the stored information, an improvement effect determination circuit for comparing the result of the level difference determination circuit with a predetermined set value, and a result of the improvement effect determination circuit 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 volume level when the howling is detected next after the filter setting. It is possible to inform the operator of the gain improvement effect by displaying the result. In addition, by determining whether the gain improvement effect is large or small and displaying the result, it is possible to give a warning against sound quality deterioration due to careless filter setting. Further, when the gain improving effect is small, the setting of the corresponding filter is canceled and the howling suppressing operation is ended, whereby it is possible to prevent the sound quality deterioration due to the excessive filter setting.

[0014]

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

In FIG. 1, 1 is a microphone for collecting performances and voices in the field, 2 is a microphone amplifier, 3 is a volume, 4 is howling suppressing means, 5 is a power amplifier, 6 is a speaker, 7 is 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 is a display means.

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

A signal picked up from the microphone 1 is amplified by the microphone amplifier 2 and input to the volume 3. The volume 3 changes the audio signal level to be output according to the control signal from the volume control circuit 7. Volume 3 with no sound
By gradually increasing the level of, the loop gain of the reproducing system becomes large, and howling occurs when it exceeds 1. The signal that has passed through the volume 3 is filtered by the howling suppressing means 4 and is amplified by the power amplifier 5 and the speaker 6. The howling suppressing means 4 sets a filter for suppressing howling according to a 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 howling and howling frequency, and outputs the presence or absence of howling to the volume control circuit 7 and the howling frequency to the filter selection circuit 9, respectively. The volume control circuit 7 controls the level of the volume 3 stepwise from the minimum level until the occurrence of howling is confirmed by the howling occurrence detection signal, and returns to the initial value when the howling is detected. Further, the filter selection circuit 9 controls the howling suppressing means so as to have a filter characteristic of attenuating the corresponding frequency according to the howling detection frequency signal, and suppresses the first howling point. In this embodiment, a notch filter is used as the filter. The control progress is input from the volume control circuit 7 to the level difference determination circuit 10, and the level difference determination circuit 10 stores the peak value of the control progress as the first howling detection level. The volume control circuit 7 further adjusts the volume 3 until the level at which the next howling occurs.
To suppress the second howling point in the same manner. Similarly, the level difference determination circuit 10 stores the second howling detection level, determines the level difference from the first howling detection level, and outputs the result to the display means 11. The display means 11 displays the value of the input signal as the gain improving effect of the first filter. 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 this embodiment, the volume control circuit 7 for generating the howling, the howling detection circuit 8 for detecting the howling occurrence and the frequency, and the control process of the volume control circuit 7 are used before and after the setting of each filter. A level difference discriminating circuit 10 for discriminating a level difference for generating and detecting howling and a display unit 11 for displaying the discriminated level difference as a gain improving effect by setting a filter are used to suppress the howling. The operator can immediately be informed of the gain improvement effect of (1) with a few operations.

Further, it is possible to inform the gain improving effect of the entire howling suppressing apparatus by adding up and displaying the discriminant value of each filter.

(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 the description thereof will be omitted.
Reference numeral 12 is an improvement effect determination circuit, and 13 is a display means.

The operation of the howling suppressing apparatus having the above structure will be described below.

The result of discrimination from the level discrimination circuit 7 is input to the improvement effect discrimination circuit 12. Improvement effect determination circuit 1
Reference numeral 2 compares the determined gain improving effect with a preset setting value of a desired gain improving effect, determines the magnitude of the gain improving effect by the filter setting, and outputs it to the display means 13. The display means 13 displays a warning according to the result when the gain improving effect is small. The display means 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 howling occurrence and the frequency, and the control process of the volume control circuit 7 are set before and after each filter setting. Level difference determination circuit 10 for determining a level difference for generating and detecting howling, and an improvement effect determination circuit for comparing the result of the level difference determination circuit 10 with a preset gain improvement setting value to determine the gain improvement effect of the filter. By providing 12 and the display means 13 for displaying a warning when the improvement effect is small as a result of the determination, the operator is instantly notified of the magnitude of the gain improvement effect of the filter set for howling suppression with some operation. As a result, it is possible to give a warning against sound quality deterioration due to careless filter setting.

(Third Embodiment) A howling suppressing apparatus according to a third embodiment will be described below 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 the description thereof will be omitted.
Further, the same item number as in FIG. 2 shows the same name and the same operation, and the description thereof will be omitted. Reference numeral 14 is a forced termination control circuit.

The operation of the howling suppressing 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. When the gain improvement effect is small, the forced termination control circuit 14 sends a termination command to the volume control circuit 7 and the filter selection circuit 9, and the volume control circuit 7 controls the volume 3 according to the input determination result.
To the initial value, and the filter selection circuit 9 executes forced termination so as to cancel the setting of only the corresponding filter. Therefore, the 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 howling occurrence and frequency, and the control progress of the volume control circuit are set before and after each filter setting. A level difference discriminating circuit 10 for discriminating a level difference for generating and detecting howling, and an improvement effect discriminating circuit 12 for comparing a result of the level difference discriminating circuit 10 with a preset gain improvement set value to judge a gain improving effect of a filter. And the forced termination control circuit 14 that prohibits the setting of the corresponding filter and terminates the howling suppression operation when the improvement effect is small as a result of the determination, thereby preventing the sound quality deterioration without setting the filter having the small gain improvement effect. And howling can be effectively suppressed.

[0030]

As described above, the volume for varying the audio signal level, the howling detection circuit for detecting howling from the varied audio signal, the filter selecting circuit for setting the filter for suppressing the howling, and the volume A howling suppressing unit that applies the filter to the output signal, a volume control circuit that controls the volume with 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 suppressing unit. By providing a level difference discriminating circuit for discriminating and a display means for displaying the result of the level difference discriminating circuit, the level of the volume level at which the howling detected by the filter is detected and the volume level at which the howling occurs after the filter is set. From the difference,
The gain improving effect by the filter setting can be known, and the result is displayed, so that the operator is informed of the value of the gain improving effect.

Further, a volume for varying the audio signal level, a howling detection circuit for detecting howling from the varied audio signal, a filter selecting circuit for setting a filter for suppressing the howling, and an output signal for the volume as described above. 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 discriminating a howling level difference from the state of the volume control circuit and the state of the howling suppression means. The gain improving effect is provided by including a discriminating circuit, an improvement effect determining circuit that determines the result of the level difference determining circuit and a predetermined set value, and a display unit that displays the result of the improvement effect determining circuit. It is possible to judge the size of the Those having an effect becomes possible to give a warning to sound quality degradation by a constant.

Further, a volume for varying the audio signal level, a howling detection circuit for detecting howling from the varied audio signal, a filter selecting circuit for setting a filter for suppressing the howling, and an output signal for the volume as described above. 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 discriminating 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 determining circuit for comparing and comparing the result of the level difference determining circuit with a predetermined set value, and a forced termination signal to the filter selecting circuit and the volume control circuit according to the result of the improving effect determining circuit. With 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 drawings]

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

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

FIG. 3 is a block diagram of a howling suppressing 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]

 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)

[Claims] 1. A volume for varying an audio signal level, a howling detection circuit for detecting howling from the varied audio signal, a filter selecting circuit for setting a filter for suppressing the howling, and an output signal for the volume as described above. Howling suppression means to filter,
A volume control circuit for controlling the volume by a signal from the howling detection circuit, a state of the volume control circuit and a state of the howling suppressing means are sequentially stored, and a level difference for discriminating a howling level difference from the stored information. A howling control device comprising a discriminating circuit and display means for displaying a result of the level difference discriminating circuit. 2. 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, and an output signal for the volume as described above. Howling suppression means to filter,
A volume control circuit for controlling the volume by a signal from the howling detection circuit, a state of the volume control circuit and a state of the howling suppressing means are sequentially stored, and a level difference for discriminating a howling level difference from the stored information. A howling suppressing apparatus comprising: a discriminating circuit, an improvement effect determining circuit for comparing and comparing the result of the level difference discriminating circuit with a predetermined set value, and display means for displaying the result of the improving effect determining circuit. 3. A volume for varying an audio signal level, a howling detection circuit for detecting howling from the varied audio signal, a filter selecting circuit for setting a filter for suppressing the howling, and an output signal for the volume as described above. Howling suppression means to filter,
A volume control circuit for controlling the volume by a signal from the howling detection circuit, a state of the volume control circuit and a state of the howling suppressing means are sequentially stored, and a level difference for discriminating a howling level difference from the stored information. A discriminating circuit, an improvement effect determining circuit for comparing and comparing the result of the level difference determining circuit with a predetermined set value, and a forced termination signal to the filter selecting circuit and the volume control circuit according to the result of the improving effect determining circuit. And a howling suppression device including a forced termination control circuit for sending out.