JP6875164B2 - Signal processor and active noise canceling system - Google Patents

Description

The present invention relates to a signal processor and an active noise canceling system.

ANC (Active Noise Cancellation) is a technology that has been conventionally realized in earphones and headphones. For example, a microphone built into an earphone captures ambient sound as environmental sound (environmental noise), inverts the phase of the captured sound, and adds it to the reproduced signal from the speaker. The noise that enters the inside of the earphone from the outside is canceled by the signal whose phase is inverted, and the user can hear only the reproduced signal from the speaker.

In the conventional ANC, when a strong wind hits the microphone and a wind noise is generated, it is output from the speaker as a large noise together with the reproduced signal, which may cause discomfort to the user. Since the wind noise is not noise that enters the earphone from the outside, the cancel noise signal is not appropriate, and an extra component related to the wind noise is output (see Patent Documents 1 and 2).
Patent Document 1 Japanese Patent Application Laid-Open No. 2008-60759 Patent Document 2 US Pat. No. 9020157

In the noise canceling process, it is desired to detect abnormal noise such as wind noise from the environmental noise and generate a noise canceling signal so as not to cause discomfort to the user.

In the first aspect of the present invention, two or more input units and two or more input units are arranged in the first output unit and the second output unit of different channels that output sound, respectively, and detect environmental noise. The detection results of the cancel noise signal generator that generates a cancel noise signal from the detected environmental noise, the abnormal noise detection unit that detects abnormal noise from the environmental noise detected by two or more input units, and the abnormal noise detection unit. Accordingly, a signal processing device including an adjusting unit for adjusting the level of the canceling noise signal output from the canceling noise signal generating unit and a first mixer for mixing the canceling noise signal and the reproduced signal is provided.

In the second aspect of the present invention, there is provided an active noise canceling system including the signal processing device of the first aspect and a signal source for outputting a reproduced signal.

The above outline of the invention does not list all the features of the present invention. A subcombination of these feature groups can also be an invention.

The configuration of the active noise canceling system according to this embodiment is shown. The block diagram of the 1st configuration example of the active noise canceling system which concerns on this embodiment is shown. The block diagram of the abnormal noise detection unit is shown. The flow chart of the noise canceling operation of the active noise canceling system which concerns on this embodiment is shown. The block diagram of the 2nd configuration example of the active noise canceling system which concerns on this embodiment is shown.

Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the inventions that fall within the scope of the claims. Also, not all combinations of features described in the embodiments are essential to the means of solving the invention.

FIG. 1 shows the configuration of the active noise canceling system 100 according to the present embodiment. The active noise canceling system 100 performs noise canceling processing on the reproduced signal supplied from the signal source 110 by using the environmental noise detected by the input units 210 and 215 in the signal processing device 120, and the noise canceling processed reproduction. The signal is output from the first output unit 200 and the second output unit 205.

FIG. 2 shows a block diagram of a first configuration example of the active noise canceling system 100 according to the present embodiment. The active noise canceling system 100 includes a signal source 110 and a signal processing device 120.

The signal source 110 supplies a reproduction signal such as a music signal. The signal source 110 may generate and supply a reproduction signal from digital data stored in a storage device such as a CD, DVD, hard disk drive, or flash memory. Further, the signal source 110 may wirelessly receive data from a specific website, cloud service, or the like to generate a reproduction signal.

The signal processing device 120 mixes and outputs a noise canceling signal with the reproduced signal supplied from the signal source 110. The signal processing device 120 may be a DSP (digital signal processor) as an example. The signal processing device 120 includes a first output unit 200, a second output unit 205, two or more input units 210 and 215, an abnormal noise detection unit 220, an adjustment unit 230, a cancel noise signal generation unit 240, and the like. A first mixer 250 is provided.

The first output unit 200 and the second output unit 205 receive the signal-processed reproduced signal, convert it into an acoustic signal, and output a sound such as music. When the received signal is a digital signal, the first output unit 200 and the second output unit 205 may perform digital-to-analog conversion of the signal to generate an analog signal, amplify the analog signal, and output it as sound. .. The first output unit 200 and the second output unit 205 have different channels, for example, the first output unit 200 is a right channel and the second output unit 205 is a left channel, and may be provided in separate housings from each other. .. The first output unit 200 and the second output unit 205 may have earphones, headphones, or the like as an example.

Two or more input units 210 and 215 are arranged in the first output unit 200 and the second output unit 205, respectively, and detect ambient noise. The two or more input units 210 and 215 may convert the input environmental noise into an electric signal, convert the electric signal into a digital signal, and output the electric signal. The two input units 210 and 215 are incorporated into the housing provided with the first output unit 200 and the housing provided with the second output unit 205, respectively, so that when the signal processing device 120 is used, the two input units 210 and 215 are incorporated. , Input units 210 and 215 are arranged apart from each other at predetermined intervals. A plurality of two or more input units 210 and 215 may be provided in at least one of the first output unit 200 and the second output unit 205. The two input units 210 and 215 may be different channels from each other, and may be, for example, a right channel microphone and a left channel microphone.

The abnormal noise detection unit 220 is connected to the outputs of two or more input units 210 and 215, detects abnormal noise from the environmental noise detected by the two or more input units 210 and 215, and outputs a detection result. The abnormal noise detection unit 220 may output, for example, the gain setting value used by the adjustment unit 230 as the detection result. The abnormal noise detection unit 220 may detect noise that is difficult to enter the inside of the first output unit 200 and the second output unit 205 and is difficult to reach the user's ear as abnormal noise. As an example, the abnormal noise detection unit 220 may detect a wind noise as an abnormal noise. The wind noise is noise generated when a strong wind hits, for example, the first output unit 200 or the second output unit 205.

The adjusting unit 230 is connected to the input units 210 and 215 and the abnormal noise detecting unit 220, and adjusts the level of the cancel noise signal output from the cancel noise signal generating unit 240 according to the detection result of the abnormal noise detecting unit 220. To do. When the abnormal noise detecting unit 220 detects an abnormal sound (for example, when the abnormal noise level exceeds the threshold value), the adjusting unit 230 lowers the level of the digital signal of the environmental noise input to the cancel noise signal generating unit 240. You may output it. As a result, the adjusting unit 230 can adjust the level of the cancel noise signal output from the cancel noise signal generation unit 240. The adjusting unit 230 may adjust the level of the digital signal received from one or both of the two input units 210 and 215 and output the digital signal. The adjusting unit 230 may be provided at any position between the input units 210 and 215 and the first mixer. Here, the level of the signal or environmental noise to be adjusted or the like indicates, for example, the volume, the sound pressure level, the amplitude, or the like, and the same applies hereinafter.

The cancel noise signal generation unit 240 generates and outputs a cancel noise signal from the digital signals of the environmental noise detected by the two or more input units 210 and 215. The cancel noise signal generation unit 240 may be connected to the adjustment unit 230 and invert the phase of the digital signal output by the adjustment unit 230 to generate a cancellation noise signal having a phase opposite to that of the digital signal. Since the cancel noise signal generation unit 240 generates a cancel noise signal from the digital signal whose level has already been adjusted by the adjustment unit 230, it is possible to output a cancellation noise signal having a level corresponding to the detection result of abnormal noise. The cancel noise signal generation unit 240 may generate a cancellation noise signal of the right channel and a cancel noise signal of the left channel, respectively, from the environmental noise detected by the input units 210 and 215 having different channels. Further, the cancel noise signal generation unit 240 may generate a cancellation noise signal common to the right channel and the left channel from the environmental noise detected by one of the input units 210 and 215.

The first mixer 250 is connected to the output of the cancel noise signal generation unit 240 and the output of the signal source 110, and mixes the cancellation noise signal from the cancellation noise signal generation unit 240 and the reproduction signal from the signal source 110 (for example). (Addition), and the mixed signal is output to the first output unit 200 and the second output unit 205. When the mixed signal in which the cancel noise signals are mixed is output from the first output unit 200 and the second output unit 205, the ambient environmental noise is combined with the components of the cancel noise signal and canceled. As a result, the user can only hear the sound of the reproduction signal.

Next, the abnormal noise detection unit 220 will be described in detail. FIG. 3 shows a block diagram of the abnormal noise detection unit 220. The abnormal noise detection unit 220 includes a second mixer 300, a third mixer 310, a comparison unit 320, and a gain calculation unit 330.

The second mixer 300 generates in-phase components of environmental noise detected by two or more input units 210 and 215. The second mixer 300 is connected to the outputs of the two input units 210 and 215, and generates in-phase components by mixing digital signals from the input units 210 and 215 according to the environmental noise. For example, in the second mixer 300, by adding the digital signals from the two input units 210 and 215 to each other without inverting, the antiphase components of the two digital signals with respect to each other are substantially canceled, and the same. It is possible to generate a signal of a phase component. Here, the environmental noise to be noise-cancelled that invades the first output unit 200 and the second output unit 205 is noise emitted from a position separated by a certain distance, and therefore is a time point detected by the input units 210 and 215. It is a sound with almost the same phase. Therefore, the in-phase component generated by the second mixer 300 corresponds to the environmental noise to be noise-canceled.

The third mixer 310 generates anti-phase components of environmental noise detected by two or more input units 210 and 215. The third mixer 310 is connected to the outputs of the two input units 210 and 215 and mixes the digital signals from the two input units 210 and 215 to generate anti-phase components. For example, the third mixer 310 inverts the phase of only one of the digital signals from the two input units 210 and 215 and adds the two digital signals to each other. As a result, the third mixer 310 can substantially cancel the in-phase components of the digital signals from the input units 210 and 215 with respect to each other, and generate a signal having an anti-phase component. Here, the abnormal noise (for example, wind noise) that is difficult to enter into the first output unit 200 and the second output unit 205 is noise emitted near the input units 210 and 215, and the noise is separated by a certain distance. At the time of detection by the two input units 210 and 215, the sounds have different phases. Therefore, the anti-phase component generated by the third mixer 310 corresponds to the abnormal noise.

The comparison unit 320 compares the in-phase component and the anti-phase component of the environmental noise. The comparison unit 320 is connected to the second mixer 300 and the third mixer 310, and compares the in-phase component from the second mixer 300 with the anti-phase component from the third mixer 310 to compare the results. You may output it. For example, the comparison unit 320 may detect the presence or absence of abnormal noise and at least one of the abnormal noise levels.

The gain calculation unit 330 is connected to the comparison unit 320 and the adjustment unit 230, and generates a gain setting value used for level adjustment in the adjustment unit 230 according to the comparison result of the comparison unit 320. When the comparison result indicates that the abnormal sound level exceeds the threshold value (for example, a value of 0 or more), the gain calculation unit 330 reduces the gain setting value, and the abnormal sound level of the comparison result is equal to or less than the threshold value. If this is indicated, the gain setting value may be increased or maintained. The gain setting value may be set in the range of 0 or more and 1 or less as an example.

Next, the noise canceling operation of the active noise canceling system 100 according to the present embodiment will be described. FIG. 4 shows a flow chart of a noise canceling operation of the active noise canceling system 100 according to the present embodiment.

First, the noise canceling operation is started in response to the power of the signal processing device 120 being turned on or the signal processing device 120 detecting environmental noise.

In S410, the input units 210 and 215 detect environmental noise. The input units 210 and 215 generate and output a digital signal corresponding to the environmental noise.

In S420, the abnormal noise detection unit 220 detects the abnormal noise. The abnormal noise detection unit 220 compares the in-phase component from the second mixer 300 with the anti-phase component from the third mixer 310, and outputs a gain setting value according to the comparison result. The abnormal noise detection unit 220 outputs a gain setting value of less than 1 when the abnormal noise is detected or the abnormal noise level exceeds the threshold value, and when the abnormal noise is not detected or the abnormal noise level is equal to or lower than the threshold value. May output a gain setting value of 1.

The abnormal noise detection unit 220 may set the gain setting value smaller as the signal level of the anti-phase component of the environmental noise becomes larger. For example, the comparison unit 320 may refer to the ratio (level of the signal of the anti-phase component / signal level of the in-phase component) or difference (of the signal of the anti-phase component) of the level of the signal of the anti-phase component to the level of the signal of the in-phase component. Level-Signal level of in-phase component) is calculated. The gain calculation unit 330 may set the gain setting value smaller as the ratio or difference is larger. Further, the comparison unit 320 compares the level of the anti-phase component of the environmental noise with a predetermined threshold value (for example, a value of 0 or more), and if the level of the anti-phase component is larger than the threshold value, it is assumed that abnormal noise is detected. A predetermined gain setting value (for example, a value less than 1) may be set.

In S430, the adjusting unit 230 adjusts the level of environmental noise according to the presence or absence of abnormal noise detected by the abnormal noise detecting unit 220 or the level of abnormal noise. The adjusting unit 230 may adjust the level of environmental noise and output it according to the gain set value from the abnormal noise detecting unit 220. For example, the adjusting unit 230 may adjust the level by multiplying the level of the digital signal of the environmental noise from the input units 210 and 215 by the gain set value. At this time, when the gain setting value = 1 (when the abnormal noise detection unit 220 does not detect abnormal noise or when the abnormal noise level is below the threshold value), the adjusting unit 230 inputs a digital signal of environmental noise to the input unit 210. And 215 will output at the original level output.

Further, the adjusting unit 230 may gradually lower the level of environmental noise when the abnormal noise detected by the abnormal noise detecting unit 220 exceeds the threshold value. For example, the adjusting unit 230 may gradually lower the level to the level specified by the gain set value in a predetermined period. Further, the adjusting unit 230 may lower the level of environmental noise to a level defined by the gain set value at a predetermined rate of change.

Further, when the level of the abnormal noise detected by the abnormal noise detecting unit 220 becomes equal to or less than the threshold value after the level of the environmental noise is lowered, the adjusting unit 230 may raise the level of the environmental noise, preferably gradually increasing the level of the environmental noise. Raise to. For example, when the abnormal noise detecting unit 220 stops detecting the abnormal noise, the adjusting unit 230 sets the level of the digital signal of the environmental noise to the original level output by the input units 210 and 215 at a predetermined period or changing speed. Raise to. Specifically, when the adjusting unit 230 receives the gain setting value = 0.3 to lower the environmental noise level and then receives the gain setting value = 1, it sets the gain setting value to be used from 0.3 to 1. It may be increased stepwise over a predetermined period or rate of change. By gradually adjusting the level in this way, the level can be adjusted naturally so as not to give the user more discomfort.

In S440, the cancel noise signal generation unit 240 generates and outputs a noise cancellation signal from the digital signal of the environmental noise from the adjustment unit 230, and the first mixer 250 mixes the reproduction signal and the cancellation noise signal. By outputting the signals mixed in this way from the first output unit 200 and the second output unit 205, the influence of abnormal noise can be suppressed and the environmental noise can be canceled. In the first mixer 250, the noise canceling signal generated by the environmental noise from the right channel is mixed with the reproduction signal of the right channel, and the noise canceling signal generated by the environmental noise from the left channel is reproduced by the left channel. May be mixed with signal.

In S450, the noise canceling operation ends when the signal processing device 120 is turned off or the signal processing device 120 stops detecting environmental noise. Further, if the signal processing device 120 is not turned off and environmental noise is further detected, the operation returns to S410.

The active noise canceling system 100 of the present embodiment can lower the level of the noise canceling signal when an abnormal noise is detected during the ANC operation, and can suppress the user from being uncomfortable.

Next, a second configuration example of the active noise canceling system 100 according to the present embodiment will be described. FIG. 5 shows a block diagram of a second configuration example of the active noise canceling system 100 according to the present embodiment. The description of substantially the same configuration as the configuration of the active noise canceling system 100 of the first configuration example shown in FIG. 2 will be omitted. The active noise canceling system 100 of the second configuration example has the same configuration and operation as the active noise canceling system 100 of the first configuration example. However, the adjusting unit 230 is arranged between the output of the cancel noise signal generating unit 240 and the input of the first mixer 250.

The adjusting unit 230 receives the cancel noise signal output from the cancel noise signal generation unit 240, and sets the level of the cancel noise signal according to the presence or absence of the abnormal noise detected by the abnormal noise detecting unit 220 or the level of the abnormal noise. You may adjust and output. When the level of the abnormal noise detected by the abnormal noise detecting unit 220 exceeds the threshold value, the adjusting unit 230 may lower the level of the cancel noise signal, preferably gradually. Further, the adjusting unit 230 may gradually increase the level of the cancel noise signal when the level of the abnormal noise detected by the abnormal noise detecting unit 220 becomes equal to or less than the threshold value after lowering the level of the cancel noise signal. Here, the adjusting unit 230 may adjust the level of the cancel noise signal in the same manner as the adjustment unit 230 of the active noise canceling system 100 of the first configuration example.

In the signal processing device 120 of the active noise canceling system 100 according to the present embodiment, the cancel noise signal generation unit 240, the abnormal noise detection unit 220, the adjustment unit 230, and the first mixer 250 perform digital signal processing. Is to do. The signal processing device 120 can cancel the noise more effectively by the noise canceling process of the digital configuration. However, the signal processing device 120 of the active noise canceling system 100 according to the present embodiment may perform analog processing on the analog signals corresponding to the environmental noise from the input units 210 and 215 to perform noise canceling processing. ..

Further, the signal processing device 120 of the active noise canceling system 100 according to the present embodiment does not have to include the first output unit 200 and the second output unit 205, and the first output unit 200 and the second output unit 205 may include the first output unit 200 and the second output unit 205. It may be externally connected to the signal processing device 120 by wire or wirelessly.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various changes or improvements can be made to the above embodiments. It is clear from the description of the claims that such modified or improved forms may also be included in the technical scope of the present invention.

The order of execution of operations, procedures, steps, steps, etc. in the devices, systems, programs, and methods shown in the claims, specification, and drawings is particularly "before" and "prior to". It should be noted that it can be realized in any order unless the output of the previous process is used in the subsequent process. Even if the scope of claims, the specification, and the operation flow in the drawings are explained using "first", "next", etc. for convenience, it means that it is essential to carry out in this order. It's not a thing.

100 Active noise canceling system, 110 signal source, 120 signal processing device, 200 1st output unit, 205 2nd output unit, 210 input unit, 215 input unit, 220 abnormal noise detection unit, 230 adjustment unit, 240 cancel noise signal generation Part, 250 1st mixer, 300 2nd mixer, 310 3rd mixer, 320 comparison part, 330 gain calculation part

Claims (10)

Two or more input units that are arranged in the first output unit and the second output unit of channels that output sound and detect environmental noise, respectively.
A cancel noise signal generation unit that generates a cancellation noise signal from the environmental noise detected by the two or more input units, and a cancel noise signal generation unit.
An abnormal noise detection unit that detects abnormal noise from the environmental noise detected by the two or more input units, and an abnormal noise detection unit.
An adjusting unit that adjusts the level of the cancel noise signal output from the cancel noise signal generation unit according to the detection result of the abnormal noise detection unit.
A first mixer for mixing the cancel noise signal and the reproduction signal is provided .
When the abnormal noise detection unit detects an abnormal noise, the adjusting unit determines the level of the environmental noise input to the cancel noise signal generation unit or the level of the cancel noise signal output from the cancel noise signal generation unit. Signal processing device that lowers. The abnormal noise detection unit
A second mixer that generates in-phase components of the environmental noise detected by the two or more input units, and
A third mixer that generates an anti-phase component of the environmental noise detected by the two or more input units, and
The signal processing device according to claim 1. The signal processing device according to claim 2, wherein the abnormal noise detection unit includes a comparison unit that compares an in-phase component and an anti-phase component of the environmental noise. The signal processing device according to any one of claims 1 to 3, wherein the abnormal noise detection unit detects wind noise as the abnormal noise. The adjustment unit is configured depending on the level of noise that abnormal sound detecting unit detects the cancellation noise signal 4 from claim 1, which is input to the generating unit lowers the level of level or the cancellation noise signal of the environmental noise The signal processing apparatus according to any one of the above. The signal processing device according to any one of claims 1 to 5, wherein the adjusting unit gradually lowers the level of the environmental noise or the level of the cancel noise signal input to the cancel noise signal generation unit. When the level of the environmental noise input to the cancel noise signal generation unit or the level of the abnormal noise detected by the abnormal noise detection unit after lowering the level of the cancel noise signal becomes equal to or lower than the threshold value, the adjusting unit said. The signal processing device according to any one of claims 1 to 6 , wherein the level of the environmental noise input to the cancel noise signal generation unit or the level of the cancel noise signal is gradually increased. The two or more input units convert the input environmental noise into a digital signal.
The cancel noise signal generation unit, the abnormal noise detection unit, the adjustment unit, and the first mixer shall be any one of claims 1 to 7 for performing digital signal processing on the digital signal. The signal processing apparatus described. The signal processing device according to any one of claims 1 to 8 , further comprising the first output unit and the second output unit. The signal processing device according to any one of claims 1 to 9.
The signal source that supplies the playback signal and
Active noise canceling system with.

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