JPH0822117B2 - Broadcast volume control device in public space - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a volume control device for broadcasting equipment used in public spaces such as stations and open spaces.
The present invention relates to a broadcast sound volume control device that realizes optimum sound volume control according to human ear characteristics by using fuzzy control.

[0002]

2. Description of the Related Art Conventionally, broadcasting in public facilities such as stations has been performed with a fixed volume preset in consideration of ambient noise. However, such fixed-volume broadcasting has a disadvantage that the listener cannot hear the broadcast sound when the noise is temporarily excessive, for example, when rushing to work or school. .
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 switching the preset fixed volume at a predetermined time, the broadcast volume during the rush hour is higher than that during normal operation. It has been proposed that the listener be able to hear the broadcast sound by increasing the.

[0003]

By the way, noise in open public spaces such as stations is generated by noise from automobiles, airplanes, passing trains, and factories around stations in addition to the standard noise as a base. Various specific noises are overlapped, and the magnitude of the noise constantly fluctuates. FIG. 1 shows a case where the noise level is actually measured, and it can be confirmed that the noise level constantly fluctuates within a range of about 20 dB to 30 dB. Therefore, the broadcasting device used under such a situation is required to have a volume adjusting function according to the fluctuation of the noise level. In order to obtain a broadcast environment in which the broadcast sound can be heard, the broadcast volume must be set in consideration of the maximum value of the fluctuating noise level, and the live broadcast sound becomes excessive and makes listeners uncomfortable. There was a problem that the broadcast sound itself became new noise for residents around the station. On the contrary, if the broadcast volume is set too low with respect to the noise level, there is a problem that the broadcast sound cannot be heard due to noise.

Here, as a method of controlling the broadcast volume in accordance with the noise level, it is also 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. 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, and as shown in FIG.
Usually, since a minute fluctuation component is superimposed, if the broadcast volume is controlled by the above method, the broadcast volume is directly affected by the change in the noise level, which is annoying. Even if a small fluctuation component of the noise level is removed using an electric circuit (smoothing circuit, etc.), the broadcast volume will increase sharply due to the sudden increase in the noise level, and the broadcast accompanying the sudden decrease in the noise level will occur. It is impossible to eliminate the discomfort experienced by the human ear due to extreme changes in the broadcast volume, such as an excessive decrease in volume. 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. The present invention has been made in view of such problems, and in an environment in which the noise level fluctuates in a complicated manner, the broadcast volume is controlled so as to match the characteristics of the human ear, and a broadcast that does not always cause an offensive effect is provided. It is an object of the present invention to provide a control device for a broadcast sound volume that does not generate new noise in the surrounding environment.

[0005]

In order to achieve the above-mentioned object, a control device according to the present invention is an electronic volume (61) which receives a volume instruction of a level (volume instruction level) determined according to the fluctuation situation of the ambient noise level. ), And appropriately and variably amplifying the broadcast signal from the source sound source (7) to output the broadcast sound of the volume instruction level, and the broadcast sound by the broadcast means and the broadcast sound. Volume measuring means (2) for measuring a synthesized sound with ambient noise mixed in the sound source, a measurement signal measured by the volume measuring means, and a broadcast signal obtained from the broadcasting means are separately rectified and smoothed. Based on the signal processing means (3) and the two kinds of output signals output by the signal processing means, the noise level of the ambient noise is calculated for each constant control cycle, and the time series of the amount of change is sequentially calculated. Memorizing time series storage means (4), judging means (4) for judging whether or not the increase or decrease of the noise level is stable based on the time series of the stored noise level change amount, and the increase or decrease of the noise level Is determined to be stable, the volume instruction level is determined by fuzzy inference using the time series of the noise level change amount as an input value, while it is determined that the increase or decrease in the noise level is unstable. Characteristically includes a volume indicating means (4, 5) for determining a volume instruction level that follows an increase or decrease in the noise level at a predetermined follow-up rate and for giving the determined volume instruction level to the electronic volume. ing.

[0006] In the broadcasting apparatus according to the present invention, the volume instruction level is changed according to the fluctuation of the ambient noise level to control the broadcast volume, but the volume instruction level is determined based on the result of fuzzy inference. There are features. Since the fuzzy inference is used, it is possible to perform control in conformity with the characteristics of the human ear simply by constructing a fuzzy rule based on an empirical rule, and for example, as in the invention of claim 2, the noise level rapidly increases. In this case, the broadcast volume is made to follow the increase in the noise level with a delay, when the noise level stabilizes, the broadcast volume is made to match the audible level that has a predetermined relationship with the noise level, and when the noise level sharply decreases, It is possible to easily realize the control of the broadcast volume so that the volume quickly follows the decrease of the noise level.

However, while the broadcast volume has a minimum required base volume that must be maintained, if the broadcast volume is made to follow the increase in the noise level indefinitely, it is rather unpleasant to the listener. Therefore, as in the invention of claim 3, the minimum volume (= base volume) and the maximum volume that are determined independently of the noise level are set in advance, and the volume instruction level is determined within the range. preferable. It is preferable that the current time is determined as an input value by fuzzy inference, instead of setting the base volume as a fixed value. Also, if the audible level is set lower than the noise level by a predetermined value (audible level difference in FIG. 3), the broadcast sound is always buried in the noise in the peripheral area of the public space even when the level of the broadcast sound increases. It is preferable because it will happen.
It should be noted that the human ear can listen to broadcast sound without any trouble even if the broadcast sound is lower than the noise level by an audible level difference.

[0008]

The broadcasting means is, for example, CH (channel).
It is composed of an amplifier, an electronic volume control, and a loudspeaker, and appropriately amplifies a broadcast signal from a source sound source with a variable gain and outputs a broadcast sound of a volume instruction level. Volume measuring means, for example,
It is a microphone and measures the synthesized sound of the sound broadcast by the broadcasting means and the ambient noise mixed therein. The signal processing means is a measurement signal measured by the volume measuring means,
Broadcast signals obtained from the broadcasting means are separately rectified and smoothed. The time-series storage unit calculates the noise level of the ambient noise for each constant control cycle based on the two types of output signals output from the signal processing unit, and sequentially stores the time series of the amount of change. Here, the noise level change amount is
It is a concept that includes the direction of change between increasing state and decreasing state,
For example, it is given as a positive or negative numerical value. The stored time series is, for example, the noise level change amount for the past three times.
The noise level is typically calculated by subtracting the broadcast signal from the measurement signal, but since both signals are rectified and smoothed, they are not affected by fine fluctuation components of the noise level. A filter circuit may be provided to remove noise components in the frequency range that does not affect listening. The determination means determines whether or not the increase / decrease of the noise level is stable, based on the stored time series of the noise level change amount. For example, if the noise level change amount repeats positive and negative values, it is determined that the increase or decrease of the noise level is unstable, while the noise level change amount keeps a positive or negative value. However, if the noise level is increasing or decreasing, it is determined that the increase or decrease in the noise level is stable. The volume instructing means operates differently depending on whether or not the increase / decrease of the noise level is stable. When the increase / decrease of the noise level is stable, it is considered that the noise level is in the process of increasing or decreasing. Therefore, the volume instruction level is determined by fuzzy inference using the time series of the noise level change amount as an input value. Although it is expressed that the volume instruction level is determined by fuzzy inference, the tracking rate to the noise level is determined by fuzzy inference as in the embodiment, and the volume instruction level is determined based on this tracking rate. It is a concept that includes doing. On the other hand, when the increase / decrease in the noise level is unstable, the noise level itself is considered to be relatively stable. Therefore, the volume instructing means determines the volume instructing level so as to follow the increase / decrease in the noise level at a predetermined follow-up rate. Then, the determined volume instruction level is given to the electronic volume to control the optimum broadcast volume according to the variation of the noise level. The time series storage means, the determination means, and the sound volume instruction means are, for example, a CPU that executes the above processing, a memory that stores this processing program, an A / D converter, a D / A converter, and a smoothing circuit. Will be realized in.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a broadcast volume control device according to the present invention will be described below with reference to the drawings. The configuration of the control device 1 according to the present invention is as shown in FIG. 4, and includes a measuring unit 2, a signal processing unit 3, a control unit 4, a post-processing unit 5, and a volume amplifying unit 6.
Composed of and. The measuring means 2 collects external sound (combined sound of broadcast sound and noise), and includes a microphone 2a. 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 pre-processing 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 rectifying circuits 31a and 31b, the smoothing circuits 32a and 32b and the filter. And the circuit 33. The measurement signal A input from the measuring unit 2 is filtered by the filter circuit 33 to remove noise components that do not affect the listening of the broadcast sound.
The signal is rectified by the rectifier circuit 31a, the fine fluctuation component is removed by the smoothing circuit 32a, and the microphone-side input signal C is supplied to the control means 4. Further, the signal processing means 3 performs the same signal processing as the microphone side input signal C with the rectifying circuit 31b and the smoothing circuit 32b on the audio signal B from the output of the volume amplifying means 6, and the control means 6 amplifies. It is supplied as the side input signal D.

The characteristic of the signal processing means 3 is preferably known, and a linear one is preferably used. When 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 gains of the microphone side input signal C and the amplifier side input signal D are matched. 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. Input signals C and D on the microphone and amplifier sides
In this case, logarithmic conversion for controlling according to human hearing is performed, and this is also performed by the signal processing means 3 or the control means 4.
You may do either.

The control means 4 is for controlling the broadcast sound 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 sound volume. Then, the control signal E is supplied to the post-processing means 5. The control means 4 is an A / D converter 41 that digitizes the input signals C and D from the signal processing means 3, a CPU 42 that processes noise evaluation and control by digital calculation, and a D that converts a digital control amount into an analog signal. /
An A converter 43, a fuzzy inference unit 44 that determines the degree of tracking of noise changes, a P1045 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, it is desirable that the characteristic of the volume amplifier 62 with respect to the control signal E (adjustment signal F) is known, and it is preferable to use an exponential function. If it cannot be expressed by a certain function,
The control means 4 stores the relationship between the two as a conversion table. The source sound source 7 supplies a sound 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.

The present control device 1 constructed as described above
Uses the CPU 42 as the center of the control means 4, integrates various auditory conditions between the measurement signal A and the audio signal B, evaluates noise, and intervenes a procedure for instructing the broadcast volume. Therefore, it is necessary to associate the relationship between the control means 4 and the external sound in advance, separately from the volume control procedure. As shown in FIG. 4, the sound signal G from the source sound source 7 is exponentially converted by the sound volume amplifying means 6 in response to a sound volume instruction (control signal E) from the control means 4 with a decibel value, and is emitted to the outside as broadcast sound. However, since the human ear responds to this broadcast sound with a logarithmic value (decibel value), the control device 1 also performs logarithmic conversion of the external sound collected by the microphone 2a in order to adapt it to the human hearing. There is. Therefore, it is necessary to determine in advance the relationship between the volume instruction value V from the control means 4 and the input Z from the measurement means 2.

Therefore, the pre-adjustment of the control means 4 will be described below. In performing this pre-adjustment, first, the control means 4 is prepared with a certain programming procedure. This program procedure establishes an adjustment coefficient for adjusting the gain of the amplifier-side input signal D to the microphone-side input signal C, and a conversion constant between the volume indication value and the measurement input for the same volume, and is connected to the CPU 42. It is operated from the keyboard and display (not shown). The adjustment coefficient and the conversion constant are determined by the speaker 8a and the microphone 2
It is appropriately determined depending on the installation state of a. 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 control means Z ₁ : Microphone side input (dB) in control means Z ₂ : Amplifier side input (dB) in control means a ₁ , A ₂ : An expression called a constant term is given.

Here, the above equations are expressions that are adjusted at the time of output of the D / A converter 43 so that the coefficient of V becomes 1, and the coefficient is the volume for two points of the volume instruction value V. Is determined by actually measuring. The constant term a ₁ is a conversion constant for the same sound volume on the measuring means 3 side and the post-processing means 5 side in the control means 4. In calculating the noise level N, the following equation is obtained: 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 point can be obtained as N = 10 log ₁₀ (Z ₁ -cZ ₂ ………………………………). Is Z ₁ when the constant is confirmed
Since the noise component contained in is not negligible, the value of Z ₁ is
Only the noise component where the output of the reference sound source is stopped is continuously measured, and the noise component is removed to determine the constant terms a ₁ and c.
The reason why the test sound source with 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. In addition, the difference between the measurement times of the microphone-side input and the amplifier-side input is the A / D in the control means.
The conversion input timing can also be adjusted by shifting it according to the distance between the microphone and the loudspeaker.

At the time of 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 further set in the control means, and the change amount is tracked in time series. Register the rate (%) in the fuzzy reasoning section. The audible level difference means a difference between the noise level and the audible level, and the audible level means a broadcast volume which is lower than the noise level but does not hinder listening. Since the human ear can hear even the broadcast sound below the noise level in a noisy environment, the broadcast volume should be determined within this hearable range as shown in FIG. It is assumed that the volume amplification means 6 is instructed as the target volume, which is a volume lower than the noise level by the audible level difference. As a result, in the external space, the volume of the broadcast sound that is lower than the noise level by the audible level difference is always emitted. As for the audible level difference, since the volume indication value grasps the volume difference in the external space by the decibel value, this setting can be made by the decibel value.

The base volume is a minimum volume that the listener can hear. 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 it is necessary to maintain the minimum volume, regardless of the measured noise level. The lower limit must be set for the volume indicator. 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. In addition,
The lower limit of the target volume calculated by converting from the noise level is
Use the volume indication value for 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, in the present control device, since the control means can directly manipulate the relationship between the volume indication value and the volume of the external space by the decibel value, the maximum volume rise based on the base volume is set in the control means. As a result, 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. The designation of the bass volume is performed by fuzzy inference, but it is realized by registering the decibel value for each time zone in advance. That is, the fuzzy inference unit 44 continuously changes the bass volume over 24 hours. Since the registered decibel value needs to be converted into the volume instruction value of the control unit 4 according to the installation state of the speaker 8a and the microphone 2a, the conversion program determines the conversion constant d.

This is compared with the volume instruction value V ₀ 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 listener's position. This _{relationship, V 0 = F 0 + d} , V = F + d ........................... V 0: the base volume volume indication value V: volume indication value (dB) _{F 0:} fuzzy inference section registered volume F : Fuzzy inference sound volume (decibel) In this way, if the conversion constant d is defined at a specific one time, the base sound volume instruction value V at any time is the sound volume of the sound volume F and F ₀ inferred at that time. It can be calculated by the difference and the conversion constant d, and the volume control program calculates the indicated value of the bass volume for each control cycle.

By the way, in the control device according to the present invention,
Since the broadcast volume is controlled in consideration of auditory conditions, the broadcast volume is not made to directly follow the target volume obtained by subtracting the audible level difference from the noise level, but the current broadcast level (that is, the volume indication value) and the target As shown in FIG. 3, the deviation amount is an excess or deficiency with respect to the sound volume, and the deviation amount is followed at a certain rate (following rate). This tracking rate is determined according to the noise waveform. That is, the element that represents the noise waveform is
For example, there are a noise change amount calculated by the difference of the noise level obtained for each control cycle of the CPU, a time series of the change amount, and a combination thereof. Considering the auditory conditions for these combinations. Set the tracking rate. Fuzzy inference is used for setting rules in consideration of 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 discontinuous, comprehensively calculates, 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 increases 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 falls, the follow-up rate is set to be larger than that when the noise level rises, and the volume is quickly lowered.

The volume instruction value is calculated by multiplying the deviation amount by the follow-up rate to calculate the amount of change in the volume instruction value, and adding or subtracting the variation amount 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 sharply rises, the volume finally rises with the same gradient as the noise in the state of time delay as shown in FIG. 2, and when the noise reaches the stable level, the follow-up rate increases. To reach the target volume. Further, in order to set the audible level difference, the actual volume during the rise becomes equal to or lower than the audible level, but since the human has the discriminating ability, the difference is not a problem, and the auditory condition is prioritized. It should be noted that the time required for the calculation processing of the evaluation of the noise waveform cannot be ignored in comparison with the case where it is configured by an electric circuit, but this is not a problem for the purpose of considering the auditory sense. 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.

Next, the procedure for controlling the broadcast sound volume using the control device 1 will be described with reference to the flowchart of FIG.
(1) First, at the beginning of the control cycle, the fuzzy inference unit 44 calculates the bass volume F and obtains the indicated value V of the bass volume by an equation. (2) Then, the inputs on the microphone side and the amplifier side are digitally converted, and the noise level N is calculated by the formula. (3) Next, the maximum volume is calculated from the base volume and the registered maximum volume increase, and the maximum allowable noise level is calculated using the conversion constant. The maximum allowable volume of the noise level calculated by the formula is set as the upper limit value. This is to cut at the time of input in order to smooth the output. (4) Decrease the audible level difference from the noise level and convert at a ₁ to obtain the target value of the target volume. At this time, the bass volume is set as the lower limit value of the volume instruction value. (5) Next, using the previous volume instruction value as the current broadcast volume, the difference from the target volume instruction value is used as the deviation amount. (6) 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. (7) And
The deviation amount is multiplied by the follow-up rate to obtain the change amount of the volume instruction value, and this is adjusted to the previous volume instruction value to obtain the volume instruction value in the current control cycle.

As an example of the above control, the result of the volume adjustment output for the model waveform of noise 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 amount of change is all positive or negative, the follow-up rate is calculated using the auditory condition as a rule.
When positive and negative are mixed in the time series, it means that the noise waveform is unstable, and a fixed tracking rate specified separately is adopted. This tracking rate is balanced with the numerical value registered in the fuzzy inference unit. Further, 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. For example, when the control device 1 controls the volume of a plurality of broadcasting facilities, a plurality of measuring means 2 are required, and in the control means 4, the input signal supplied from the signal processing means 3 is time-divided. It is also possible to calculate and process.

[0024]

According to the present invention, the following excellent effects can be obtained. (1) Since the broadcast sound volume control device according to the present invention controls the broadcast sound volume with the audible level reduced by the audible level difference from the noise level, the broadcast sound is always heard by the listener even in the changing noise. The volume is audible. Also,
The broadcast volume in the surrounding environment is lower than the noise level by the audible level difference and the volume corresponding to the distance from the speaker. Therefore, even if the noise is loud, the broadcast sound will be at the noise level. You will not be aware of it in the following situations. If the noise level becomes lower than the base volume and the base volume is broadcast,
Although the broadcast sound exceeds the noise level and affects the surrounding environment, 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 broadcasting in public spaces such as stations, there is a volume that must be maintained safely even when the noise is low,
Since this is stored as the base volume independently of the noise level, the minimum volume is guaranteed regardless of the 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. Further, since the characteristic of the measuring unit and the distance between the speaker and the microphone are grasped at the adjustment stage of the apparatus, the setting of the level difference of the output volume with respect to noise can be directly instructed by the decibel value. (4) Since the volume is adjusted after removing the fluctuation of the actually measured noise level, the harshness due to this fluctuation is eliminated. Further, when the noise level is suddenly increased, the broadcast sound volume is increased with a time lag with respect to the increase in the noise level, so that the discomfort caused by the increase in the broadcast sound 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, since the broadcast volume finally reaches the target volume when the noise is at a stable level, it is possible to hear the broadcast sound, and when the noise drops, the decrease in the broadcast volume slightly delays the decrease in the noise level. As it descends quickly, it is not uncomfortable.
Furthermore, when the noise level exceeds the set maximum volume level or becomes lower than the base volume, it is controlled with this as a target, so sudden volume changes can be avoided, and in the end,
With the control as described above, it is possible to perform broadcasting considering the characteristics of the ear.

[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 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

Claims (5)

[Claims] 1. Set according to the fluctuation situation of the surrounding noise level.
An electronic device that receives a volume level (volume level)
Equipped with a volume, the broadcast signal from the source sound source is appropriately
By variable amplification to
Broadcast means for outputting sound, broadcast sound by this broadcast means, and ambient noise mixed in with it
Sound volume measuring means for measuring the synthesized sound of the sound volume, the measurement signal measured by the sound volume measuring means,
Rectify the broadcast signal obtained from the transmission means separately.
.Based on the signal processing means for smoothing and two kinds of output signals output by this signal processing means
Calculate the noise level of ambient noise every fixed control cycle
Then, the time series memory that sequentially stores the time series of the amount of change
And noise based on the time series of the stored noise level change amount.
Judgment means for judging whether the level increase / decrease is stable
And when it is determined that the increase / decrease in noise level is stable,
Is a fuzzy with the time series of the noise level change as an input value.
The volume indication level is determined by inference, while the noise level is
If it is determined that the increase or decrease in
The volume instruction level that follows the increase and decrease in the noise level
The electronic volume, and
Control device for broadcasting sound in public spaces, characterized in that it comprises a volume indicating means, the providing the volume. 2. The fuzzy reasoning has a sudden noise level.
When increasing dramatically, increase the broadcast volume to increase the noise level.
When the noise level is stabilized by following the delay
Is an audible level that has a predetermined relationship between the broadcast volume and the noise level.
And when the noise level decreases sharply,
Control to make the broadcast volume follow the decrease in noise level quickly
What is achieved by the fuzzy rules that realize
The control device for controlling the broadcast volume in a public space according to claim 1 . 3. The volume level indicating means is independent of the noise level.
And the maximum volume of the minimum volume that will be determined in the relationship (base volume)
Within the range of,
The broadcast volume control device in a public space according to claim 1 or 2 . 4. The current time is used as an input value for the bass volume.
And is determined by fuzzy reasoning.
The broadcast volume control device in a public space according to claim 3 . 5. The audible level is predetermined from the noise level
The value is set to a lower value, which allows
In the surrounding area, even if the level of broadcast sound increases,
The feature is that the transmitted sound is always buried in the noise.
A control device for controlling a broadcast volume in a public space according to any one of claims 2 to 4 .