JP2011151634A - Gain automatic setting device and gain automatic setting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gain automatic setting device and a gain automatic setting method for automatically setting a gain only with a microphone which is on a transmitter side. <P>SOLUTION: A wireless microphone 1 to which the gain automatic setting device is applied is equipped with a control part 14 which is constituted of: a microphone control part 141 which controls each part; a peak detection part 142 which detects a peak in a voice signal; and a gain setting part 143 which performs predetermined arithmetic processing for gain automatic adjustment to set the gain. Background noise is input from the microphone 1 in first predetermined time, and the average value of input levels of the background noise is calculated. Voice from a user is further inputted in second predetermined time, and peak values of the voice are detected by the peak detection part 142, and the average value of the peak values is calculated. Then, the gain to be set is determined from the average value of the input levels of the background noise and the average value of the peak values. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an automatic gain setting device and an automatic gain setting method, and more particularly, to an automatic gain setting device and an automatic gain setting that are applied to a microphone and can automatically set an amplifier gain based on the level of background noise. Regarding the method.

  When voice is input to a microphone in a room such as a hall, classroom, office, or outdoors, the voice quality of the user varies depending on the individual, the loudness of the user's voice, and the input music Therefore, it is necessary to appropriately adjust the audio input level or the output volume. Therefore, generally, a gain is manually set in a microphone amplifier or the like to which a microphone is connected. When the microphone is a wireless microphone, the gain is generally set manually on the receiver side that receives sound from the wireless microphone.

  If the gain has to be adjusted manually each time a microphone is used, the operation is complicated and a lot of time is wasted. In addition, in a space such as the above-described hall, there is usually so-called background noise that sounds in the space in addition to the user's voice and music to be input to the microphone. When a microphone is used, the background noise is also input as voice. Therefore, in order to properly adjust the gain of the microphone, it is necessary to consider the influence of the background noise. Therefore, a certain level of skill and experience is required to manually adjust the gain of the microphone.

  In a wireless microphone system, the transmitter and the receiver are usually installed apart from each other. Therefore, when the user himself sets the gain, the place where the microphone is used and the receiver are installed. Therefore, there is a problem in that adjustments cannot be made quickly because the movement to the place must be repeated. Therefore, an automatic volume adjustment device that can automatically perform volume setting has been proposed (Patent Document 1).

JP-A-10-56346

  However, the volume automatic adjustment device described in Patent Document 1 needs to include a speaker that outputs sound from a broadcast source and a microphone that collects sound output from the speaker in order to adjust the volume. There is. Therefore, when the gain automatic setting device described in Patent Document 1 is applied to microphone gain adjustment, there is a problem that the number of parts increases.

  In addition, there is a problem that even if an attempt is made to use a speaker provided in a space such as a hall using a microphone, the volume cannot be adjusted because the filter or the like constituting the invention is not provided.

  Accordingly, an object of the present invention is to provide an automatic gain setting apparatus and automatic gain setting method capable of automatically setting a gain only with a microphone on the transmitter side, not on the receiver side.

  In order to solve the above-described problems, the present invention is a microphone that collects background noise at a first predetermined time, collects voice at a second predetermined time, and converts it into an audio signal, and a microphone A microphone amplifier that amplifies the sound signal converted by the above, a peak detector that detects a peak value of the input level of the sound, an average value of the input level of the background noise at the first predetermined time, and a plurality of peak values The gain automatic setting device includes a gain setting unit that sets a gain of the microphone amplifier based on an average value in a second predetermined time.

  The present invention also includes a first sound collecting step for collecting background noise with a microphone at a first predetermined time and converting it into a background noise signal, and collecting sound with a microphone at a second predetermined time. A second sound collecting step for converting the sound signal into a sound signal, an amplification step for amplifying the sound signal converted by the microphone with a microphone amplifier, a peak detecting step for detecting a peak value of the sound input level, and an input of background noise A gain automatic setting method comprising a gain setting step of setting a gain of a microphone amplifier based on an average value of a level at a first predetermined time and an average value of a plurality of peak values at a second predetermined time. .

  According to the present invention, the microphone gain can be automatically set based on the background noise and the input sound level without forcing the user to perform complicated work. Further, gain setting can be automatically performed using only a microphone for inputting sound without using a device other than a microphone such as a speaker.

It is a block diagram which shows the structure of the wireless microphone to which the gain automatic setting apparatus which concerns on one embodiment of this invention is applied. It is a flowchart which shows the procedure of the gain automatic setting process by the wireless microphone to which the gain automatic setting apparatus is applied. It is a flowchart which shows the procedure of the gain automatic setting process by the wireless microphone to which the gain automatic setting apparatus is applied. It is the schematic which shows the procedure of the volume adjustment by the wireless microphone to which the gain automatic setting apparatus is applied. It is a graph which shows the relationship between the average value of the peak value of an audio | voice input level, a gain characteristic, and the average value of the input level of background noise.

Embodiments of the present invention will be described below. The description will be given in the following order.
<1. Embodiment>
<2. Modification>
The embodiment described below is a preferred specific example of the present invention, and various technically preferable limitations are given. However, the scope of the present invention is particularly limited to the present invention in the following description. Unless otherwise stated, the present invention is not limited to these embodiments.

<1. Embodiment>
"Configuration of automatic gain setting device"
FIG. 1 is a diagram showing a schematic configuration of an example of an automatic gain setting device according to an embodiment of the present invention. In this embodiment, the gain automatic setting device is applied to the wireless microphone 1 that transmits the voice input by the user to the receiver by wireless communication. The wireless microphone 1 includes a microphone 10, a microphone amplifier 11, an A / D (Analog to Digital) conversion unit 12, an audio processing unit 13, a control unit 14, a storage unit 15, an operation unit 16, a notification unit 17, a wireless communication unit 18, and It consists of an antenna 19. In FIG. 1, a solid line indicates an audio signal, and a dotted line indicates a control signal.

  Hereinafter, a person who inputs sound using the wireless microphone 1 is referred to as a user. Further, the voice input to the wireless microphone 1 by the user's voice is simply referred to as voice, and is distinguished from background noise. However, the sound input to the wireless microphone 1 is not limited to the voice of the user, and various sounds such as the sound of a musical instrument and the output sound from the playback device can be input.

  The microphone 10 is for inputting background noise and voice from the user. The voice input to the microphone 10 is converted into an analog voice signal and sent to the microphone amplifier 11. The microphone amplifier 11 is for amplifying the analog audio signal sent from the microphone 10 based on the gain set by the calculation result of the gain setting unit 143 to be described later and sending it to the A / D conversion unit 12. The A / D converter 12 is an A / D converter for converting an analog audio signal into a digital audio signal. The audio processing unit 13 performs predetermined processing such as adjustment of the number of quantization bits and adjustment of the sampling rate on the audio signal transmitted from the A / D conversion unit 12.

  The control unit 14 is a microcomputer composed of, for example, a CPU (Central Processing Unit) and the like, and includes a microphone control unit 141 that controls each part of the wireless microphone 1 and a peak that detects a peak in the audio signal. The detection unit 142 includes a gain setting unit 143 that performs a predetermined calculation process for automatic gain setting and sets a gain. The control unit 14 is connected to the microphone amplifier 11 and sends a control signal for controlling the gain setting of the microphone amplifier 11 based on the calculation result by the gain setting unit 143. Details of the arithmetic processing performed by the gain setting unit 143 will be described later.

  The storage unit 15 stores various values used for automatic gain setting, such as the average value of the background level of background noise, the peak value of the input level of the audio signal, and the average value of the peak value calculated by the calculation processing by the gain setting unit 143. It is a memory for storing and holding.

  The operation unit 16 is connected to the control unit 14, and is used by a user who performs voice input to switch the wireless microphone 1 on and off. In the present embodiment, the operation unit 16 is provided as a switch that is provided on the housing of the wireless microphone 1 so as to be operated by the user and can be switched on and off.

  The notification unit 17 is connected to the control unit 14 and is used for prompting the user to input voice or notifying the user that the arithmetic processing has been completed. In the present embodiment, the notification unit 17 is configured by an LED (Light Emitting Diode) that is provided so that the light emitting unit is exposed from the housing of the wireless microphone 1 and that notifies the user of the above by turning on or flashing. Has been.

  The wireless communication unit 18 is for transmitting a sound signal that has been subjected to predetermined processing and amplified to the receiver (not shown) via the antenna 19 by wireless communication. The wireless communication system is not particularly limited, such as a TDMA (Time Division Multiple Access) system, Bluetooth (registered trademark), or ZigBee, and various systems can be used.

[Operation of automatic gain setting device]
The wireless microphone 1 to which the gain automatic setting device according to the present embodiment is applied has the above-described configuration. Next, gain automatic setting processing by the wireless microphone 1 will be described with reference to FIGS.

  When automatic gain setting is performed by the wireless microphone 1 to which the automatic gain setting device is applied, it is first determined in step S1 whether or not the switch as the operation unit 16 has been turned on by the user. When the switch of the operation unit 16 is not switched on and remains off (No in step S1), automatic gain setting is not started and the process ends. When the switch of the operation unit 16 is switched on (Yes in step S1), the process proceeds to step S2. In step S2, the power of the wireless microphone 1 is turned on, the LED as the notification unit 17 is lit as shown in FIG. 4A, and the user is notified that the automatic gain setting process has started.

  Next, the user who has confirmed that the LED serving as the notification unit 17 has been lit starts to input background noise as shown in FIG. 4B, whereby the background noise is input in step S3. Background noise is input from the microphone 10. Here, the background noise is a sound other than a specific sound when attention is paid to a specific sound when a plurality of sounds exist at the same time. In the present invention, the user speaks to the wireless microphone 1. Refers to the voice other than the voice to be input. In step S4, predetermined signal processing such as A / D conversion and integration processing is performed on the background noise input in step S3.

  Next, in step S5, it is determined whether or not a first predetermined time has elapsed since the start of input of background noise. The first predetermined time is the background noise measurement time. If it is determined that the first predetermined time has not elapsed (No in step S5), the process returns to step S3, and steps S3 to S5 are repeated until the first predetermined time elapses. Background noise is input. The first predetermined time, which is the background noise measurement time, is set to 1 second, for example. However, the first predetermined time is not limited to one second. For example, when there is a variation in the input level of background noise, the first predetermined time may be set longer than 1 second in order to measure background noise in more detail. Further, the user may arbitrarily set the first predetermined time.

  As described above, when the LED as the notification unit 17 is turned on in step S2, the automatic gain setting process is started, and the user only has to start the input of background noise. It functions as a notification that prompts input of noise. Therefore, for example, when the input of background noise is no longer necessary after the first predetermined time has passed, the LED of the notification unit 17 is turned off as shown in FIG. You may be made to prompt the end of.

  If it is determined in step S5 that the first predetermined time has elapsed (Yes in step S5), the process proceeds to step S6. In step S6, the average value (hereinafter referred to as the background noise average level) of the background level of the background noise input by repeating steps S3 to S5 for the first predetermined time is calculated. Then, the calculated background noise average level is stored in the storage unit 15.

  Next, in step S7, as shown in FIG. 4D, the user inputs voice. Since the user usually inputs the voice in the space where the background noise input in step S3 is present, in step S7, the user speaks and inputs the microphone 10 to the microphone 10. The voice and background noise to be input are input. When the LED of the notification unit 17 is turned off at the end of the first predetermined time for inputting background noise as shown in FIG. 4C, in order to prompt the user to input voice when starting to input voice, As shown to FIG. 4D, it is good to light up LED of the notification part 17 again. At this time, lighting of the LED as the notification unit 17 may be the same as the lighting at the time of background noise input, but when the user inputs the background noise by lighting it in a color different from that at the time of background noise input. You may make it distinguishable.

  Next, in step S8, the peak detector 142 detects the peak value of the input level of the voice input in step S7 described above (hereinafter referred to as the voice peak value). A known technique is arbitrarily adopted for detection of the voice peak value. Next, in step S9, it is determined whether or not n or more audio peak values are stored in the storage unit 15. Here, n is the number of voice peak values used for calculating the average value of the voice peak values at the second predetermined time. The second predetermined time is a measurement time of voice input by the user. When the number of voice peak values stored in the storage unit 15 is smaller than n (No in Step S9), Step S11 and Step S12 are not performed, and the process proceeds to Step S10.

  In step S10, the voice peak value detected in step S8 is stored in the storage unit 15. In addition, since the audio | voice peak value is not stored in the memory | storage part 15 before an automatic gain setting process, in the first step S9 after the start of an automatic gain setting process, a process always progresses to step S10.

  Next, in step S13, it is determined whether or not a second predetermined time has elapsed since the start of voice input by the user. When it is determined that the second predetermined time has not elapsed (No in step S13), the process returns to step S7. Then, Steps S7 to S10 and Step S13 are repeated until the number of voice peak values stored in the storage unit 15 reaches n, so that voice input by the user, voice peak value detection, and voice peak value Storage is performed. Note that all the voice peak values detected in step S8 are stored in the storage unit 15 as needed until the number of stored voice peak values reaches n.

  If it is determined in step S9 that n number of audio peak values are stored in the storage unit 15, the process proceeds to step S11 (Yes in step S9). In step S11, the most recent speech peak value detected in step S8 (the (n + 1) th speech peak value not yet stored in the storage unit 15) is the n speech peak values stored in the storage unit 15. A determination is made as to whether it is greater than either. If it is determined that the most recent sound peak value is smaller than any sound peak value stored in the storage unit 15 (No in step S11), the process in step S12 is not performed, and the process proceeds to step S13. .

  On the other hand, when it is determined in step S11 that the most recent sound peak value detected in step S8 described above is larger than any of the n sound peak values stored in the storage unit 15 (Yes in step S11). ) Proceeds to step S12. In step S12, the latest speech peak value determined to be larger than any of the n speech peak values is stored in the storage unit 15, and the n speech peak values stored in the storage unit 15 are stored. The voice peak value is replaced by discarding the minimum voice peak value.

  Next, it is determined whether or not the second predetermined time has elapsed in step S13. If it has not elapsed (No in step S13), steps S7 to S9 and steps S11 to S13 are repeated, Until the second predetermined time elapses, voice input by the user, detection of the voice peak value, comparison, and replacement processing are performed.

  As a result of the series of processes from step S8 to step S13 described above, finally, the storage unit 15 stores the five audio peak values in order from the largest of the plurality of audio peak values at the second predetermined time. 15 is stored. For example, when n = 5 is set, the comparison determination in step S11 is not performed until the fifth sound peak value, but is performed from the sixth sound peak value. For the sixth and subsequent voices, the newly input voice peak value is compared with the five voice peak values held in the storage unit 15 at any time, and the five voices whose latest voice peak values are held in the storage unit 15 are compared. If it is larger than any of the peak values, the latest voice peak value and the minimum voice peak value among the five voice peak values are replaced. By repeating this process, finally, as shown by the arrow in the graph of FIG. 4D, five voices in order from the larger one of the plurality of voice peak values within the second predetermined time. The peak value is stored in the storage unit 15. That is, it can be said that five audio peak values are sampled in descending order.

  If it is determined in step S13 that the second predetermined time has elapsed (Yes in step S13), the process proceeds to step S14. In step S14, an average value of the n sound peak values stored in the storage unit 15 (hereinafter referred to as a sound peak average value) is calculated. The voice peak average value can be calculated, for example, by dividing the total of n voice peak values stored in the storage unit 15 by n, which is the number of voice peak values. Next, in step S15, the microphone gain to be set is obtained based on the background noise average level calculated in step S6 and the sound peak average value calculated in step S14.

  In addition, while performing the process in step S14 thru | or step S16, you may make it notify a user that the gain automatic setting process is being performed by blinking LED of the notification part 17, etc. If the LED of the notification unit 17 is lit when prompting the input of background noise and voice input by the user, it is possible to distinguish between voice input and processing in progress by blinking.

  Here, the calculation of the gain in step S15 will be described with reference to the graph shown in FIG. The graph of FIG. 5 shows the relationship between the gain characteristic relative to the sound peak average value and the background noise average level, with the horizontal axis representing the gain set for the microphone amplifier 11 and the vertical axis representing the sound peak average value. . As shown in the graph, the gain characteristics are defined as four patterns corresponding to the level of the background noise average level. The characteristic A is a characteristic when the average background noise level is minimum, and the background noise average level increases in the order of the characteristics B, the characteristics C, and the characteristics D. The four patterns of the gain characteristics are stored in the storage unit 15 in advance, and are read out and used when the control unit 14 calculates the gain. In the present embodiment, the gain is set according to four characteristics corresponding to the magnitude of the background noise average level.

  In order to obtain the gain, first, it is determined whether the background noise average level calculated in step S6 corresponds to the characteristics A, B, C, or D. The determination can be performed, for example, by setting three threshold values for the average background noise level and determining whether the average background noise level is equal to or higher than each threshold value. Then, the gain is determined based on any of the characteristics A to D corresponding to the background noise average level.

  When the background noise average level is small (characteristic A), the gain is set so as to increase in proportion to the decrease in the voice peak average value, and the characteristic A is linear. This is because the influence of background noise on gain adjustment is considered to be small when the background noise average level is small. Accordingly, when the voice peak average value is high, the gain is set low, and when the voice peak average value is low, the gain is set high.

  Characteristics B, C, and D are cases where the background noise average level is larger than that of characteristic A. When the background noise average level is large, the influence of the background noise on the gain adjustment is large. Therefore, when the gain is set high in proportion to the decrease in the average voice peak value as in the case where the background noise average level is small, the background noise is also amplified by the microphone amplifier 11 and is heard when output from the receiver-side speaker. It becomes difficult voice. Therefore, when the background noise average level is high, the gain is set low in a range where the audio peak value is high to some extent, and when the audio peak value falls below a predetermined value, the gain is set to increase rapidly thereafter. . This tendency is set so as to increase as the average background noise level increases. Therefore, the relationship between the voice peak average value and the gain is curvilinear.

  Therefore, even if the voice peak average value is substantially constant in the gain automatic setting process performed each time the wireless microphone 1 is used a plurality of times, the background noise average level is high when the background noise average level is large. The gain is set lower than when the value is small.

  The characteristics A, B, C, and D are set so that the gain is minimum when the average value is maximum, and the gain is maximum when the average value is minimum.

  In this way, by setting the gain based on the average of the peak value of the input level of the sound input by the user, the sound is prevented from being distorted when a large amount of sound is input, thereby improving the sound quality. Can play.

  In step S16, a predetermined control signal is sent from the control unit 14 to the microphone amplifier 11, so that the gain of the microphone amplifier 11 is set. When the gain setting in step S16 ends, the LED as the notification unit 17 is turned off in step S17 as shown in FIG. 4E, and the automatic gain setting process ends. When the process is finished, the LED of the notification unit 17 is turned off, so that the user can be notified that the automatic gain setting is finished and the wireless microphone 1 can be used.

  After the automatic gain setting is completed, the wireless microphone 1 in which the gain is set by the above-described process is used by the user. When the user inputs sound into the wireless microphone 1, the sound signal is amplified by the microphone amplifier 11 according to the gain set by the above-described processing. Next, the amplified audio signal is subjected to predetermined processing by the A / D conversion unit 12 and the audio processing unit 13 and transmitted to the receiver via the radio communication unit 18 and the antenna 19. Then, predetermined processing is performed by the receiver, and the sound is output from a speaker or the like.

  With the automatic gain setting device according to the present invention, the gain of the microphone amplifier 11 is appropriately set only by the wireless microphone 1 on the transmitter side, so that it is not necessary to manually set the gain on the receiver side, and it can be performed quickly. The use of the wireless microphone 1 can be started. Further, since the background noise and the sound signal average peak value of the sound signal are compared with a digital value, the microphone gain can be set with high accuracy by a simple method. Furthermore, since the gain setting is performed automatically, no skill or experience is required, and the user can set the gain automatically.

<2. Modification>
Although the embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible. For example, the notification unit 17 is not limited to an LED that presents information to the user by lighting, and a display such as an LCD (Liquid Crystal Display) may be used. When a display is used, a message such as “In operation”, “Enter background noise”, “Enter voice” is displayed on the display to prompt the user to input voice. You may do it. The notification to the user is not limited to visual notification using a display or the like, but may be notification by voice such as signal sound or voice guidance. Furthermore, visual notification using an LED or display and notification using sound may be used in combination.

  The operation unit 16 has been described by taking a switch that can be switched on and off as an example, but is not limited to a switch, and may be configured as a pushable button. While the user continues to press the button, background noise and the user's voice may be input from the microphone 10, and when the user stops pressing the button, the voice input may also be stopped.

  The value of n, which is the number of voice peak values used for calculating the average value of the voice input level, has been described by taking 5 as an example, but is not limited to 5, and it is necessary to calculate a more detailed voice peak average value. If there is, the value of n should be 5 or more. The user may arbitrarily set the number of n.

  In the present embodiment, the average value of the voice input level is calculated from n voice peak values having a large input level among the voice peak values. However, a predetermined threshold is set for the voice input level. It is also possible to calculate the average from a plurality of voice peak values exceeding the threshold.

  Furthermore, in the present embodiment, the gain characteristics with respect to the voice peak average value have been described by taking four patterns as an example as shown in FIG. 5, but the gain characteristics are not limited to four patterns. More patterns may be stored in the storage unit 15 as presets so that more detailed gain settings can be made.

1 ... Wireless microphone 10 ... Microphone 11 ... Microphone amplifier 12 ... A / D converter 13 ...・ Audio processing unit 14 ・ ・ ・ ・ ・ ・ Control unit 141 ・ ・ ・ ・ ・ ・ Microphone control unit 142 ・ ・ ・ ・ ・ ・ Peak detection unit 143 ・ ・ ・ ・ ・ ・ Gain setting unit 15 ..Storage unit 16 ... Operation unit 17 ... Notification unit 18 ... Wireless communication unit 19 ... Antenna

Claims (7)

A microphone that collects background noise at a first predetermined time, and further collects sound at a second predetermined time and converts it into an audio signal;
A microphone amplifier that amplifies the audio signal converted by the microphone;
A peak detector for detecting a peak value of the input level of the voice;
A gain setting unit that sets a gain of the microphone amplifier based on an average value of the input level of the background noise at the first predetermined time and an average value of the peak values at the second predetermined time When,
A gain automatic setting device. A storage unit that preliminarily stores and holds gain characteristics corresponding to the average value of the background level of the background noise and the average value of the plurality of peak values;
The gain automatic setting device according to claim 1, wherein the gain is set based on the gain characteristic.   The gain automatic setting device according to claim 2, wherein the gain is set lower when the background noise input level is higher than when the background noise input level is low.   The microphone collects the background noise at the first predetermined time and converts it into a background noise signal, and then collects the sound at the second predetermined time and converts it into an audio signal. The gain automatic setting device according to 1.   The gain automatic setting device according to claim 1, further comprising a notification unit that prompts the user to input a voice and notifies the user that the setting of the gain of the microphone amplifier has been completed.   6. The automatic gain setting apparatus according to claim 5, wherein the notification unit further notifies the user of the start and end of the first predetermined time or / and the second predetermined time. A first sound collecting step of collecting background noise with a microphone and converting it into a background noise signal at a first predetermined time;
A second sound collecting step of collecting sound with a microphone at a second predetermined time and converting the sound into a sound signal;
An amplification step of amplifying the audio signal converted by the microphone with a microphone amplifier;
A peak detection step for detecting a peak value of the input level of the voice;
A gain setting step of setting the gain of the microphone amplifier based on an average value of the input level of the background noise at the first predetermined time and an average value of the plurality of peak values at the second predetermined time When,
An automatic gain setting method consisting of

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