JPH0326926B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an automatic volume adjustment device that can automatically adjust the degree of amplification according to the noise level of a sound field.

Conventional configuration and its problems Conventional devices of this type pass noise input from a noise pickup microphone through a filter.
The system converts the signal into a DC voltage, changes the DC voltage according to the noise level, and applies voltage control to the electronic attenuator through which the announcement input signal passes, varying the degree of amplification and improving clarity. In this case, since the output changes continuously in conjunction with the noise level, the output level goes up and down even in sections where phrases, phrases, sentences, etc. are continuously uttered in the announcement broadcast, resulting in an audible sense of naturalness. was damaging.
Also, if the noise input is picked up as noise from the announcement output with automatic volume adjustment, an input/output loop will occur, so the announcement input signal should be passed through a low-cut filter, and the noise input should also be passed through a high-cut filter. In other words, loops were prevented. Due to the above constraints, the electronic attenuator is DC-controlled by detecting changes in the noise level only in the low-frequency components of the noise band generated in the sound field. However, it had the disadvantage that it was unsuitable for use in sound fields where loud noises were generated.

Purpose of the Invention In order to eliminate the drawbacks of the above-mentioned conventional example, the present invention stabilizes output level fluctuations in sections where phrases, phrases, or sentences are continuously uttered in an announcement broadcast, and ensures clarity. The purpose is to maintain the naturalness of announcement broadcasts.

Composition of the Invention In order to achieve the above object, the present invention includes a noise detection unit that detects a mid-range component from noise generated in a sound field, and an announcement unit that inputs an announcement signal and determines the presence or absence of the announcement signal. A signal detection means, an input response time setting means for setting a reference pulse of a time corresponding to a phrase, phrase, sentence, etc. in the announcement signal, and an output signal of the input response time setting means and the announcement signal detection means are combined. an amplification degree setting section that outputs a control signal of a constant amplification degree corresponding to the output signal of the noise detection section according to the output signal of the gate circuit;
and a gain adjuster that receives the announcement signal and changes the gain in accordance with the control signal.

DESCRIPTION OF EMBODIMENTS The configuration of an embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an input terminal for an announcement signal. 2 is a band pass filter, the output of which is sent to the threshold setting section 3; 4 is a rectifier circuit, and threshold setting section 3
It receives the output and outputs it to the gate circuit 5. Reference numeral 6 denotes an oscillation circuit, and outputs its output to the input response time setting section 7. The output of the input response time setting section 7 is
Output to gate circuit 5. Reference numeral 8 denotes a noise input terminal from a microphone that picks up noise, and this noise passes through a noise input level adjuster 9 and is divided into noise bands by a bandpass filter 10. 11 is a rectifier circuit, which converts the output of the bandpass filter 10 into
After converting into DC, the signal is input to the comparator 12, where the magnitude of the noise level is detected, and is led to the amplification degree setting section 14 through the lower limit value setting section 13. The output of the amplification degree setting section 14 is at DC level, and controls a gain adjuster 15 consisting of a voltage controlled amplification or the like. 1
6 is a variable volume adjuster, and 17 is an output terminal for an announcement signal. FIG. 2 shows an example of a comparison between normal noise in a sound field that requires broadcasting at a certain stadium and the cheering level when the audience cheers.
It was found that fluctuations in the noise level were concentrated around 400 to 8000 Hz, and when detecting the noise level, if this band was averaged through a filter around 400 to 4000 Hz, the noise level in the band that interfered with intelligibility could be reduced. It can be used as the amount of change and is used as the band of the bandpass filter 10.

Next, the operation of this embodiment will be explained. The announcement signal is sent from the input terminal 1 to the gain adjuster 15 and at the same time is passed through the bandpass filter 2 to be divided into bands. The output of the bandpass filter 2 is sent to a threshold setting section 3, which sets a level for determining the presence or absence of an input signal, and when the threshold is exceeded, the signal is sent to a rectifier circuit 4, and a gate circuit 5 is sent to the gate circuit 5 as a trigger signal. On the other hand, the oscillation circuit 6 oscillates a clock pulse and sends it to the input response time setting section 7. The input response time setting section 7 divides and outputs the output signal of the oscillation circuit 6, and uses a variable resistor to set the time of a reference pulse corresponding to a clause, phrase, sentence, etc. of the announcement signal. . As shown in Figure 4, even if the announcement level falls below the threshold at Δt between words in a section where the announcement clause, phrase, or sentence is continuously uttered,
Since it sounds unnatural if the degree of amplification changes, the input response time setting section 7 shown in FIG. 1 sets the reference pulse time n and has a setting range such that n>Δt. Using the reference pulse and the output of the rectifier circuit 4, a gate circuit 5 generates a signal synchronized with the rise of the input signal. Noise input is sent to the noise input terminal 8 from a microphone that collects noise, passes through a noise input level adjuster 9, and is passed through a bandpass filter 10 to detect fluctuations in the noise level in a band that affects intelligibility and rectify it. The signal is sent to circuit 11. Here, the DC-converted output is sent to the comparator 12. The comparator 12 continuously tracks fluctuations in the noise level and outputs the determined signal to the lower limit value setting section 13. Lower limit value setting section 13
Then, even when the noise level is low, the gain adjuster 15
This is to keep the amplification degree at a constant lower limit value and prevent the volume from becoming extremely low. A signal corresponding to the noise level detected through the lower limit setting section 13 is sent to the amplification degree setting section 14.
The amplification degree setting unit 14 uses a signal obtained from the gate circuit 5 and synchronized with the rising edge of the input signal.
The control voltage of the gain adjuster 15 is set according to the noise level at that time, and it is kept at a constant level during sections where clauses, phrases, sentences, etc. of the announcement signal are continuously uttered, and reset according to the noise level. This set control voltage is sent to the gain adjuster 15, where the degree of amplification is automatically adjusted for each section in which phrases, phrases, sentences, etc. are continuously uttered. Next, an overview of the operation of this embodiment will be explained using a chart with reference to FIG. A shows the change in noise input. B shows a change in the level of the announcement signal. C indicates that the amplification degree of the gain adjuster 15 is automatically adjusted to a constant volume for each phrase, etc., every time the announcement signal rises, depending on the noise level. In region A, there is no announcement broadcast, and the amplification degree of the gain adjuster 15 is kept constant at the lower limit value regardless of the noise input. In area B, there is an announcement broadcast, and since the threshold is exceeded at the rise, the amplification degree of the gain adjuster 15 is increased depending on the level of noise input at that time, and the phrase, phrase, or sentence of the announcement is etc. Keep the continuous utterances constant. In the area of C.
Since the announcement is interrupted, the amplification degree is kept constant at the lower limit value, similar to area A.

Next, as an effect of this embodiment, when performing natural volume adjustment, mid-range noise can be detected in the same sound field as announcement broadcasts, so it can cope with fluctuations in noise level within the band that affect intelligibility. This has the advantage that automatic volume adjustment is possible, and the noise frequency band can be used in any noisy environment by selecting a bandpass filter. In addition, since the announcement volume for each phrase is constant, there is no continuous change in the announcement volume within a phrase, which is required in conventional automatic volume adjustment, and the natural aural sensation can be greatly improved.

Effects of the invention (a) In places where many people cheer, such as stadiums, there is a lot of noise in the mid-range component, so by detecting this when broadcasting announcements, it is possible to detect noise in the band that has the greatest impact on clarity. This has the advantage that the amplification level can be automatically corrected in response to changes in the noise level.

(b) In synchronization with the rise of the input signal, the amplification level is automatically set in accordance with the noise level at that time, and the amplification level is automatically set for each section of the announcement broadcast that is continuously uttered, such as a clause, phrase, or sentence. By resetting the settings, it is possible to prevent the level fluctuation of announcement broadcasts during sections where phrases, phrases, or sentences are continuously uttered, and the natural feeling of hearing is greatly improved compared to the past. be.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an automatic volume adjustment device according to an embodiment of the present invention, Fig. 2 is a comparison diagram of levels by frequency during normal noise and cheering, and Figs. It is an operation chart diagram showing the operation. 1... Input terminal, 2, 10... Band pass filter, 5... Gate circuit, 8... Noise input terminal, 13...
Lower limit value setting section, 14... Amplification degree setting section, 15... Gain adjuster.

Claims (1)

[Claims] 1. A noise detection section that detects mid-range components from noise generated in a sound field, an announcement signal detection means that inputs an announcement signal and determines the presence or absence of this announcement signal, and converts the announcement signal into a phrase, phrase, sentence, etc. an input response time setting means for setting a reference pulse of a time corresponding to the time, a gate circuit for synthesizing the input response time setting means and the output signal of the announcement signal detection means, and a gate circuit for synthesizing the output signal of the input response time setting means and the announcement signal detection means; An automatic controller equipped with an amplification setting section that outputs a control signal with a constant amplification corresponding to the output signal of the detection section, and a gain adjuster that inputs the announcement signal and changes the gain according to the control signal and outputs it. Volume adjustment device.