JPH05316598A - Controller for broadcast sound volume in public space - Google Patents

Abstract

PURPOSE:To provide a controller for broadcast sound volume always enabling listeners to listen to broadcast even under the environment where a noise level is always varied and preventing the noise from becoming a new noise source for the surrounding environment at the outside of the broadcast range. CONSTITUTION:An external sound (synthesized sound between broadcast sound and noise) collected by a measurement means 2 and a reference sound signal separated by a sound amplifier means 6 are compared to detect the noise component included in the external sound and the sound volume amplification factor of the sound amplifier means 6 is determined based on the level of the noise component. Furthermore, the fuzzy deduction is used to determine the sound volume amplification factor to take a listening sense of a human being into consideration.

Description

Detailed Description of the Invention

[0001]

[Industrial application field] The present invention relates to a control device for a broadcast sound volume used in public spaces such as stations and plazas, and public facilities.

[0002]

2. Description of the Related Art Conventionally, broadcasting in public facilities such as stations is
It was done with a fixed volume preset in consideration of ambient noise.

However, in such a fixed-volume broadcasting, for example, when the noise is temporarily excessive, such as during a rush hour for commuting to work or school, the listener cannot hear the broadcast sound. was there.

Therefore, in order to avoid such inconvenience, paying attention to the fact that the rush hour occurs every day at a certain time zone, and by changing the preset fixed volume at a predetermined time, the rush hour is normally timed. There has been proposed a method of increasing the broadcast volume so that a listener can hear the broadcast sound.

[0005]

However, the above method has the following problems.

[0006] That is, in addition to the standard noise as the base, noise in automobiles, airplanes, passing trains, as well as various specific noises generated from factories and the like near the station Is superimposed, and the noise level constantly fluctuates. Here, when the case of actually measuring the noise level is shown (see FIG. 1), it can be confirmed that the noise level constantly fluctuates within a range of about 20 dB to 30 dB.

Therefore, the broadcasting apparatus used under such a situation is required to have a volume adjusting function according to the fluctuation of the noise level, but the conventional method described above does not have such a function. .. Therefore, in order to obtain a broadcast environment in which the broadcast sound can be heard all day long, it is necessary to set the broadcast volume in consideration of the maximum value of the fluctuating noise level, and the live broadcast sound becomes excessive and the listener feels uncomfortable. However, there was a problem that the broadcast sound itself became a new noise for the residents around the station.

On the contrary, if the broadcast volume is set too low relative to the noise level, there is a problem that the broadcast sound becomes inaudible due to noise.

The present invention has been made in view of the above conventional problems, and in an environment in which the noise level constantly fluctuates, a broadcast that is always audible to listeners is performed and a surrounding environment outside the broadcast range is provided. It is an object of the present invention to provide a broadcast volume control device that does not generate new noise.

[0010]

In order to solve the above problems, a broadcasting apparatus according to the present invention controls a broadcasting volume in response to a change in noise level.

By the way, as a method of controlling the broadcast volume in accordance with the noise level, it is possible to detect the noise level or the level difference between the noise level and the broadcast volume and use it as a control signal for the volume amplifier of the broadcasting apparatus. is there.

However, there are various fluctuations in the noise level, such as gentle fluctuations, sudden fluctuations, and intermittent noises, depending on the type of noise source. Further, as shown in FIG. 1, since a small fluctuation component is usually superimposed on the fluctuation, if the broadcasting volume is controlled by the above method, the broadcasting volume is directly affected by the change in the noise level, which is annoying. It will become a thing.

Further, even if fine fluctuation components of the noise level are removed by using an electric circuit (smoothing circuit etc.),
Eliminate discomfort to the human ear due to extreme changes in broadcast volume, such as a sudden increase in broadcast volume due to a sudden increase in noise level, and an unnecessary decrease in broadcast volume due to a sudden decrease in noise level. Is impossible. That is, it is impossible to control the broadcast sound volume so as to cope with the change in the noise level and to match the characteristics of the human ear only with the configuration using the electric circuit.

Therefore, as shown in FIG. 2, the inventor temporarily delays the increase of the broadcast sound volume from the increase of the noise level when the noise level sharply rises, and broadcasts when the noise level is stable. It is intended to control the broadcast volume in accordance with the characteristics of the human ear by making the volume reach an audible level and further rapidly reducing the broadcast volume when the noise level sharply decreases.

Even in a broadcasting device using such a control method, the broadcasting volume from the broadcasting device has a necessary minimum volume that must be maintained, while the broadcasting volume increases in noise level. It is also necessary to set the maximum volume, as it will give an unpleasant sensation to the listener if the user follows indefinitely.

Therefore, in order to perform the sound volume control corresponding to the fluctuation of the noise level, the broadcast sound volume control device according to the present invention comprises a sound volume amplification means having an electronic volume,
Measuring means for measuring an external sound in which noise and broadcast sound are mixed, and rectifying and smoothing the sound signal separated by the measuring signal and the sound volume amplifying means measured by the measuring means and not affecting the listening from the measured signal. A signal processing means for removing a noise component, a control means for receiving the output of the signal processing means at a constant control cycle to calculate a noise component, evaluating a noise change and determining an instructed sound volume, and an output of the control means. It is composed of post-processing means for smoothing the signal and outputting it as an electronic volume adjustment signal.

[0017]

In the control device according to the present invention, the control means compares the external sound (synthesized sound of broadcast sound and noise) collected by the measuring means with the audio signal separated from the volume amplifying means. The noise component contained in the sound is detected, and the gain of the volume amplification means is determined according to the level of this noise component.

Specifically, the external sound / voice signals are given to the signal processing means as input signals, rectified / smoothed by the signal processing means and supplied to the control means. However, since the external sound contains an unnecessary noise component that does not affect listening, the external sound is supplied to the control means after the unnecessary component is removed by the filter circuit.

The control means detects the noise level by comparing the external sound and the audio signal, which are processed by the signal processing means and supplied, and determines the gain of the volume amplifying means according to the noise level. Volume instruction is given to the amplification means.

Since the human ear can hear the broadcast sound below the noise level in the noisy environment when designating the volume, the broadcast volume should be determined within this audible range. The relationship between the volume indication value and the external volume or the measurement signal is related in advance as a conversion constant, and the difference between the audible level of the broadcast sound and the noise level is set as the audible level difference in the control means. It is assumed that the volume amplification means is instructed as the target volume with a volume that is lower than the noise level by the audible level difference as in 3.

As a result, in the external space, the volume of the broadcast sound which is lower than the noise level by the audible level difference is always emitted. It should be noted that the audible level difference is such that the volume instruction value grasps the volume difference in the external space by a decibel value, and therefore this setting is also possible by the decibel value.

Further, since the volume instruction is given according to the fluctuation of the noise level, the volume instruction value also decreases as the noise level decreases, but the broadcast sound has the minimum necessary volume that the listener can hear. Therefore, it is necessary to maintain the minimum volume and set the lower limit to the volume indication value regardless of the measured noise level. Therefore, the lower limit of the volume instruction value is stored in the control means as the volume instruction value corresponding to the minimum volume (base volume) to be maintained.

The lower limit value of the target volume calculated by converting from the noise level is the volume instruction value of the base volume. As a result, as shown in FIG. 3, the volume above the base volume is always maintained in the external space, and when the target volume calculated from the noise level reaches the base volume, the broadcast volume also starts to rise.

Further, as described above, in the present control device, the control means can directly operate the relationship between the volume indication value and the volume of the external space by the decibel value, so that the maximum rising volume based on the base volume is controlled by the control means. By setting to, it is possible to set an upper limit on the volume of the external space. It is also possible to set an upper limit to the volume instruction value by manually adjusting the volume to the maximum volume at the listener's position regardless of the base volume and storing the volume instruction value at this time.

By the way, in the control device according to the present invention,
Since the goal is to control the broadcast volume in consideration of the auditory conditions, the broadcast volume is not directly tracked to the target volume obtained by subtracting the audible level difference from the noise level. As shown in FIG. 3, the deviation amount is an excess or deficiency between the indicated value and the target sound volume, and the deviation amount is followed at a certain rate (following rate).

The following rate is determined according to the noise waveform. That is, the element representing the noise waveform is, for example, CP
There is a noise change amount calculated from the difference in the noise level obtained for each U control cycle, a time series of the change amount, and a combination thereof, and these combinations are tracked in consideration of auditory conditions. Set the rate.

Fuzzy inference is employed for setting the rule in consideration of the human hearing. The fuzzy inference unit receives a time-series set of elements representing a noise waveform, continuously treats the plurality of rules defined as discontinuity, performs a comprehensive calculation, and outputs a follow-up rate.

The specific setting of the follow-up rate is such that the follow-up rate is small for a waveform that rises steeply, and the follow-up rate is large when the change is slow. Furthermore, the follow-up rate is further reduced at the start point of the noise rise to suppress the volume change when the noise changes rapidly or when the noise is instantaneous.

As a result, as shown in FIG. 2, it is possible to perform control with a delay with respect to the noise change, and when the noise level decreases, the follow-up rate is set to be larger than that when the noise level rises, and the volume is quickly lowered. .. The tracking rate is set / stored in the control means.

For the volume instruction value, the variation amount is multiplied by the follow-up rate to calculate the change amount of the volume instruction value, and this is adjusted to the volume instruction value in the previous control cycle to determine the volume instruction value in the current control cycle. As a result, even if the volume rise is delayed when the noise suddenly rises, the volume finally rises with the same gradient as the noise in the time delay state as shown in FIG. 2, and when the noise reaches the stable level, the follow-up rate increases. To reach the target volume. Further, since the audible level difference is set, the actual volume during the rise becomes equal to or lower than the audible level, but since the human being has discrimination ability, the difference is not a problem, and the auditory condition is prioritized.

The time required for the calculation processing of the evaluation of the noise waveform cannot be ignored in comparison with the case where the circuit is composed of an electric circuit, but this is also a problem for the purpose of considering the auditory sense. I won't. In addition, the delay of control due to the distance between the loudspeaker and the measuring means does not cause a problem as long as it is intended for hearing.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a broadcast sound volume control device according to the present invention will be described below with reference to the drawings.

FIG. 4 shows the structure of a broadcast sound volume control device according to the present invention. The control device 1 comprises a measurement means 2, a signal processing means 3, a control means 4, a post-processing means 5, and a sound volume amplification means 6. Composed.

The measuring means 2 collects external sound (combined sound of broadcast sound and noise), and the microphone 2a.
Consists of. The microphone 2a converts the external sound into an electric signal and sends it to the signal processing means 3 as a measurement signal A. The measurement signal A usually has an AC waveform in which noise is superimposed on the broadcast volume.

The signal processing means 3 performs preprocessing for the control means 4 to compare and calculate the measurement signal A and the audio signal B from the volume amplification means 6, and the rectifier circuits 31a, 31.
b, smoothing circuits 32a and 32b, and filter circuit 33
It consists of and.

That is, the measuring signal A input from the measuring means 2 is rectified by the rectifying circuit 31a and the smoothing circuit 3
Fine fluctuation components are removed by 2a. After that, the filter circuit 33 removes a noise component that does not affect the listening of the broadcast sound, and supplies this to the control means 4 as the microphone side input signal C. The signal processing means 3 also performs the same signal processing as the microphone side input signal C on the audio signal B separated from the output of the volume amplification means 6 by the rectifying circuit 31b and the smoothing circuit 32b, and the control means 6 To the amplifier side input signal D.

Here, the measuring means 2 or the volume amplifying means 6
It is desirable that the characteristic of the signal processing means 3 with respect to the input from is known, and a linear one is preferably used. If this characteristic cannot be expressed by a constant function, the relationship between the two may be stored in the control means 4 as a conversion table.

Further, in order to perform the noise component calculation processing in the control means 4, adjusters (not shown) are provided on the microphone side and the amplifier side respectively, and the levels of the microphone side input signal C and the amplifier side input signal D are adjusted. To match. The gain adjustment may be performed by the control means 6 by multiplying the microphone-side and amplifier-side input signals C and D by the conversion magnification.

Further, the input signals C and D on the microphone side and the amplifier side are subjected to logarithmic conversion for control according to the human sense of hearing, and this is also performed by either the signal processing means 3 or the control means 4. May be.

The control means 4 is for controlling the broadcast volume in accordance with the amount of change in the external noise level, and for every fixed control cycle, performs arithmetic processing according to the procedure of the flow shown in FIG. 5 to determine the instructed volume. Then, the control signal E is supplied to the post-processing means 5. The control means 4 is an A / D converter 41 for digitizing the input signals C and D from the signal processing means 3, a CPU 42 for processing noise evaluation and control by digital calculation, and a D for converting a digital control amount into analog. /
An A converter 43, a fuzzy inference unit 44 that determines the degree of tracking of noise changes, a PIO 45 that transmits and receives an operation signal to and from a source sound source 7, which will be described later, and an operation unit 46 (not shown) for adjusting the entire device. No)).

The post-processing means 5 smoothes the control signal E by the smoothing circuit 51, and the electronic volume control 61 of the volume amplifying means 6.
Is supplied as the adjustment signal F.

The volume amplification means 6 receives the adjustment signal F supplied from the post-processing means 5 and amplifies the audio signal G from the source sound source 7, and is composed of an electronic volume 61 and a volume amplifier 62. Here, the characteristic of the volume amplifier 62 with respect to the control signal E (adjustment signal F) is preferably known, and is preferably an exponential function. If it cannot be expressed by a certain function, the relationship between the two is stored in the control means 4 as a conversion table.

The source sound source 7 supplies the sound or the like to be broadcast to the volume amplifying means 6, and supplies a predetermined sound (recorded sound).

The loudspeaker 8 emits the audio signal G amplified by the volume amplifier 62 to the outside, and a speaker 8a installed in the external space is used.

Thus, the control device 1 constructed as described above uses the CPU 42 as the center of the control means 4, and integrates various auditory conditions between the measurement signal A and the voice signal B. Since the noise is evaluated to intervene the procedure for instructing the broadcast volume, it is necessary to associate the relationship between the control means 4 and the external sound in advance separately from the volume control procedure. ..

That is, the audio signal G from the source sound source 7
As shown in FIG. 4, the volume amplifying means 6 is controlled by a volume instruction (control signal E) given from the control means 4 with a decibel value.
Is converted into an exponent and is emitted to the outside as a broadcast sound, but since the human ear responds to the broadcast sound with a logarithmic value (decibel value), the control device 1 also adjusts the microphone to the human hearing. The external sound collected in is logarithmically converted. Therefore, the relationship between the volume instruction value from the control means 4 and the input from the measurement means 2 needs to be determined in advance.

Therefore, the pre-adjustment of the control means 4 will be described below.

In carrying out this preliminary adjustment, first, a fixed program procedure is prepared in the control means 4. This programming procedure is performed by the microphone side input signal C of the amplifier side input signal D.
The conversion constant for adjusting the level to and the conversion constant between the volume instruction value and the measurement input for the same volume are determined, and are operated from a keyboard and a display (not shown) connected to the CPU 42. The adjustment coefficient V and the conversion constant are appropriately determined depending on the installation states of the speaker 8a and the microphone 2a.

First, in order to match the level of the amplifier-side input signal D with the level of the microphone-side input signal C, a constant sine wave signal is applied from the tester to the volume amplifier 62 as a reference sound source. And if there is no noise in the external space, Z ₁ = V + a ₁ …………………………………………………… Z ₂ = V + a ₂ …………………… …………………………………… V: Volume indication value (dB) in the control means Z ₁ : Microphone side input (dB) in the control means Z ₂ : Amplifier side input (dB) in the control means a ₁ , A ₂ : An expression called a constant term is given.

The above equations are expressed as those to be adjusted at the time of output of the D / A converter 43 so that the coefficient of V becomes 1. This coefficient is 2 of the volume instruction value V.
Determine the volume for a point by actually measuring it. Also, the constant term a
₁ is the measuring means 3 side and the post-processing means 5 in the control means 4.
It is a conversion constant for the same volume on the side.

In calculating the noise level N, the following equation is used: c = z ₁ / z ₂ = 10 ** {(a ₁ -a ₂ ) / 10} ... z ₁ : microphone side input z ₂ : amplifier side input Therefore, if this is calculated, the noise level N at an arbitrary time can be obtained as N = 10 log ₁₀ (z ₁ −cz ₂ ) ……………………………….

In practice, since the noise component contained in z ₁ cannot be ignored when the constant is determined, the value of z ₁ is obtained by continuously measuring only the noise component in which the output of the reference sound source is stopped and determining the noise component. Then, the constant terms of a ₁ and c are removed and fixed.

The reason why the test sound source having a constant volume is adopted is that in the case of a sound source such as voice or music, the microphone side input fluctuates even if the volume instruction value is constant. Also, here, the difference between the measurement time of the microphone input and the amplifier input is
It is also possible to adjust the input timing of A / D conversion in the control means by shifting it according to the distance between the microphone and the loudspeaker.

Furthermore, during the pre-adjustment of the control device 1,
The audible level difference (decibel value), the bass volume (decibel value), and the maximum rising volume (decibel value) are set in the control means, and the follow-up rate (%) of the change amount to the time series is registered in the fuzzy inference unit.

Fuzzy inference is used to specify the bass volume, and the decibel value for each time zone is registered. This base volume is specified by inputting a reference sound source having a constant volume to the volume amplifier 62 as a source sound source and manually adjusting the volume instruction value so that the listener's volume becomes the base volume. It may be set together with a measuring device to avoid ambiguity due to hearing.

The reason why the test sound source having a constant volume is adopted is that the input on the microphone side fluctuates even if the volume indication value is constant in a sound source such as voice and music. Adjust to an appropriate volume.

When a plurality of source sound sources having different volumes are provided, different indication values of the base volume are required.
This can be solved by providing the source sound source identification mechanism and the control means with a plurality of bass volume indication values. When the base volume is changed depending on the time zone or the time, it can be solved by setting the base volume as a function of the time zone or the time in the control means and using this and a timer. In all of these, if the volume difference of the source sound source itself or the volume difference due to the time zone or time is known, if the base volume indication value for one source sound source or time zone and time is determined, the other source It is possible to simultaneously determine the base sound volume indication value for the sound source, the time zone, and the time.

Thus, the fuzzy inference unit 44 continuously changes the bass volume for 24 hours. Since the registered decibel value is converted into the volume instruction value of the control means 4 in the installed state of the speaker 8a and the microphone 2a, the conversion program determines the conversion constant.

This is compared with the volume instruction value of the control means 4 when a constant volume corresponding to the source sound source is given by the reference sound source and at this time an appropriate volume is obtained at the position of the listener. This relationship is as follows: V ₀ = F ₀ + d ………………………………………………………… V ₀ : Volume indication value (decibel) that becomes the base volume F ₀ : Adjusted fuzzy Inference volume (decibels)

In this way, if the conversion constant (d) is defined at a specific one time, the base volume indication value at any time is the volume difference between the volume F ₁ and F ₀ inferred at that time and It can be calculated by the conversion constant d, and the volume control program calculates the instruction value of the bass volume for each control cycle.

Next, the procedure for controlling the broadcast volume using the control device 1 will be described below. First, at the beginning of the control cycle, the fuzzy inference unit 44 calculates the bass volume and obtains the indicated value of the bass volume by an equation.

Then, the input on the microphone side and the input on the amplifier side are digitally converted, and the noise level is calculated by a formula.

The maximum volume is calculated from the base volume and the registered maximum volume, and the maximum permissible noise level is calculated by the conversion constant. The maximum permissible volume is set as the upper limit of the noise level calculated by the formula. This is to cut at the time of input in order to smooth the output.

The audible level difference is lowered from the noise level and converted at a ₁ to obtain the target value indicating the target volume. At this time, the bass volume is set as the lower limit value of the volume instruction value.

The previous volume instruction value is the current broadcast volume, and the difference from the target volume instruction value is the deviation amount.

On the other hand, the volume change amount is calculated from the noise level for each control cycle and stored as a time series of the volume change amount. The tracking rate is calculated by the fuzzy inference unit from the time series of the noise variation.

The deviation amount is multiplied by the follow-up rate to obtain the change amount of the sound volume instruction value, and this is adjusted to the previous sound volume instruction value to obtain the sound volume instruction value in the current control cycle. As an example of the above control, the result of the volume adjustment output for the noise model waveform is shown in FIG. However, this is the case where the audible level difference is set to zero.

Here, when the time series of the variation is all positive or negative, the follow-up rate is calculated using the auditory condition as a rule, but when positive and negative are mixed in the time series, the noise waveform is unstable. It means that the fixed tracking rate specified separately is adopted. However, this tracking rate must be balanced with the numerical value registered in the fuzzy inference unit.

The broadcast sound volume control device 1 according to the present invention is not limited to the above embodiment, and the design can be changed appropriately. That is, when the control device 1 controls the volume of a plurality of broadcasting facilities, a plurality of measuring means 2 are required,
In the control means 4, the input signal supplied from the signal processing means 3 can be calculated / processed in a time division manner.

[0070]

According to the present invention constructed as described above, the following excellent effects can be obtained.

(1) Since the broadcast sound volume control apparatus according to the present invention controls the broadcast sound volume with the target of the audible level which is lower than the noise level by the audible level difference, the broadcast sound is always controlled even in the changing noise. The volume will be audible to the listener. Also, the broadcast volume in the surrounding environment is lower than the noise level by the audible level difference and is reduced by the volume corresponding to the distance from the speaker. Therefore, even if the noise becomes loud, the broadcast sound will be You will not be aware of it if it is below the noise level. When the noise level becomes lower than the base volume and the broadcast is performed at the base volume, the broadcast sound exceeds the noise level and affects the surrounding environment, but it can be said that it is unavoidable due to the nature of public broadcasting. However, this can also be mitigated by changing the bass volume in the time zone as shown in the embodiment.

(2) In a public space, particularly in broadcasting at a station, there is a volume that must be maintained for safety even when the noise is low. Since this volume is stored as a base volume independently of the noise level, the minimum volume is set. Volume is guaranteed regardless of noise level.

(3) The setting of the maximum volume level was unclear to the user of the device in the conventional device, but since it can be set clearly, it is possible to broadcast without causing any discomfort to the listener.

(4) Since the volume is adjusted after removing the fluctuation of the actually measured noise level, the harshness due to this fluctuation is eliminated. Furthermore, when the noise level rises sharply, the broadcast volume will rise with a time lag behind the noise level rise.
Discomfort caused by an increase in broadcast volume itself is reduced. Further, the momentary noise does not cause any uncomfortable feeling because the volume does not change depending on the time width. Moreover, the broadcast volume finally reaches the target volume when the noise is at a stable level, so it is possible to hear the broadcast sound.
In addition, although the decrease in the broadcast volume slightly delays the decrease in the noise level when the noise drops, it does not become uncomfortable because it quickly drops. Furthermore, when the noise level exceeds the set maximum volume level or becomes lower than the base volume, control is performed with this as a target, so that a rapid volume change can be avoided. Therefore, the above-described control enables broadcasting in consideration of ear characteristics.

[Brief description of drawings]

FIG. 1 is a graph showing an actual measurement value of a noise level around a station.

FIG. 2 is a graph showing a control state of broadcast volume with respect to fluctuations in noise level of the control device according to the present invention.

FIG. 3 is a graph showing a control method of the control device according to the present invention.

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

FIG. 5 is a flowchart showing a procedure of volume control according to the present invention.

FIG. 6 is a graph showing characteristics of control means of the control device according to the present invention.

[Explanation of symbols]

 1 Broadcast volume control device 2 Measuring means 3 Signal processing means 31a, 31b Rectifier circuit 32a, 32b Smoothing circuit 33 Filter 4 Control means 41 A / D converter 42 CPU 43 D / A converter 44 Fuzzy inference unit 45 PIO 5 After Processing means 51 Smoothing circuit 6 Volume amplification means 61 Electronic volume 62 Volume amplifier 7 Source sound source 8 Loudspeaker means A Measurement signal B Voice signal C Microphone side input signal D Amplifier side input signal E Control signal (volume indication value) F Adjustment signal G Voice signal

[Procedure amendment]

[Submission date] June 18, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

That is, the measurement signal A input from the measuring means 2 is heard by the filter circuit 33 for listening to the broadcast sound.
The noise component that does not affect the noise removal is removed, and this is rectified by the rectifier circuit 3.
1a for rectification, and smoothing circuit 32a for finer
The fluctuation component is removed and supplied to the control means 4 as the microphone side input signal C. Further, the signal processing means 3 includes the volume amplification means 6
Also for the audio signal B separated from the output of the rectifier circuit, the rectifying circuit 31b and the smoothing circuit 32b perform the same signal processing as the microphone side input signal C, and the amplifier side input signal D is supplied to the control means 6.
Supply as.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

Claims (5)

[Claims] 1. A control device for controlling a broadcast volume in a public space such as a station, comprising: a volume amplification means having an electronic volume; and a measurement means for measuring an external sound in which noise and broadcast sound are mixed. While rectifying and smoothing the measurement signal measured by the measurement means and the audio signal separated from the volume amplification means,
A signal processing unit that removes a noise component that does not affect the listening from the measurement signal, and a control unit that receives the output of the signal processing unit at every constant control cycle to calculate the noise component and evaluates the noise change to determine the instruction volume. And a post-processing unit for smoothing an output signal of the control unit and outputting it as an electronic volume adjustment signal. 2. The control means comprises an A / D converter for digitizing an input signal, a CPU for processing noise evaluation and control by digital calculation, a D / A converter for converting a digital control amount into an analog signal, and a noise change. 2. The broadcast sound volume control device according to claim 1, comprising a fuzzy inference unit that determines the degree of follow-up and an operation unit that adjusts the entire device. 3. The control means sets the difference between the audible level of broadcast sound and the noise level as an audible level difference, and instructs the volume amplifying means as a target volume with a volume lower than the noise level by the audible level difference. The volume control device according to claim 1 or 2, characterized in that. 4. The control means sets / stores a lower limit of a volume indication value as a base volume regardless of a measured noise level, and a lower limit value of a target volume calculated by converting from the noise level is a base volume. The volume control device according to any one of claims 1 to 3, wherein the volume control value is set as the volume control value. 5. A fuzzy inference unit of the control means determines an excessive or deficient amount between a current broadcast sound volume and a target sound volume as a deviation amount and determines a sound volume instruction value at a predetermined ratio with respect to the deviation amount. The volume control device according to claim 1.