Method and device for eliminating background noise of voice (1)

Method and device for eliminating voice background noise (1)

The present invention belongs to the field of voice communication, and in particular relates to a method and device for eliminating voice background noise (1).

In the field of voice communication, due to the complex environment of the caller, the audio signal collected by the audio equipment includes not only the voice signal of the caller, but also noise signals from other sound sources in the surrounding environment, such as the voice of other people. These noise signals seriously interfere with the quality of voice communication. Therefore, while maintaining high-efficiency denoising, the technology of using fewer devices to remove noise signals mixed in voice signals has become a technology for many companies. The focus of attention.

The purpose of the present invention is to provide a method for eliminating voice background noise, which aims to solve the problem that the noise signal mixed in the voice signal seriously affects the quality of voice communication.

The present invention is realized in this way, a method for eliminating voice background noise, the method includes the following steps:

A. Perform effective value detection on the received audio signal to obtain an output signal that reflects the average power of the audio signal;

B. Compare the output signal used to reflect the average power of the audio signal with a first threshold to generate a noise cancellation control signal, where the first threshold is the critical value of the average power of the voice signal and the average power of the noise signal;

C. Under the control of the noise cancellation control signal, the noise signal in the audio signal is eliminated, and the speech signal is amplified.

Another object of the present invention is to provide a device for eliminating voice background noise, the device comprising:

The effective value detection unit is used to detect the effective value of the received audio signal to obtain an output signal that reflects the average power of the audio signal;

A noise cancellation control signal generation unit, configured to compare the output signal generated by the effective value detection unit and used to reflect the average power of the audio signal with a first threshold to generate a noise cancellation control signal, where the first threshold is a voice signal The critical value of the average power of the noise and the average power of the noise signal;

The noise-removing amplifying unit is used for performing noise removal processing on the noise signal in the audio signal and amplifying the voice signal under the control of the noise-removing control signal generated by the noise canceling control signal generating unit.

In the embodiment of the present invention, by detecting the effective value of the received audio signal, the output signal reflecting the average power of the audio signal is obtained, and the output signal reflecting the average power of the audio signal is combined with the first threshold value. Comparing, generate the noise cancellation control signal, under the control of the noise cancellation control signal, the noise signal in the audio signal is eliminated, and the voice signal is amplified, so as to achieve the purpose of eliminating the voice background noise.

In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not used to limit the present invention.

In the embodiment of the present invention, by detecting the effective value of the received audio signal, the output signal reflecting the average power of the audio signal is obtained, and the output signal reflecting the average power of the audio signal is combined with the first threshold value. Compare and generate a noise cancellation control signal. The first threshold is the critical value of the average power of the voice signal and the average power of the noise signal. Under the control of the noise cancellation control signal, the noise signal in the audio signal is eliminated. The voice signal is amplified and processed to eliminate the background noise of the voice.

The first figure shows the implementation process of the method for eliminating voice background noise provided by an embodiment of the present invention, which is described in detail as follows:

In step S101, an effective value (also referred to as Root Mean Square, RMS) detection is performed on the received audio signal to obtain an output signal used to reflect the average power of the audio signal.

In the embodiment of the present invention, the received audio signal may be a collected audio signal, or may be an audio signal transmitted from another device. Because the speakers environment is generally more complex, there are multiple sources of sound besides the speaker, such as the voices of other speakers around, the sound of surrounding vehicles, etc. Therefore, the received audio signal includes not only the speakers voice Signals also include noise signals from other sound sources around the speaker. Since the received audio signal includes voice signal and noise signal, and the level amplitude generated by the voice signal is generally different from the level amplitude generated by the noise signal, by detecting the effective value of the received audio signal, according to the amplitude of the audio signal The change can generate an output signal that reflects the average power of the audio signal, that is, the output signal that reflects the average power of the audio signal reflects the amplitude change of the audio signal. According to the difference between the average power of the voice signal and the average power of the noise signal, the critical value of the average power of the voice signal and the average power of the noise signal is set as the first threshold. The output signal of the average power of the signal is compared with the first threshold to determine whether the audio signal is a speech signal or a noise signal, thereby generating a noise cancellation control signal.

Since the audio signal is generally continuous, there may be a delay in detecting the effective value of the received audio signal. In order to avoid the delay in detecting the effective value of the received audio signal and reducing the accuracy of speech noise cancellation, another aspect of the present invention In an embodiment, the step of performing effective value detection on the received audio signal to obtain an output signal reflecting the average power of the audio signal specifically includes:

A. Determine whether the received audio signal is a voice signal, and generate effective value detection trigger information based on the judgment result and the previously generated noise reduction control signal. When the effective value detection trigger signal indicates that the audio signal needs to be effective value detection When, go to step B, otherwise, go to step C. The specific process is as follows:

A1. Compare the received audio signal with the second threshold, determine whether the audio signal is a voice signal, and obtain the positive comparison result; where the second threshold is the minimum value of the forward voice signal, and its specific setting depends on the sensitivity of the microphone. And for the collection of different sound pressure noises under this sensitivity, the specific setting work should be combined with acoustic theory and experimental statistics. When comparing the received audio signal with the second threshold, when the audio signal is greater than the second threshold, the audio signal is determined to be a voice signal, and the positive comparison result is logically true; when the audio signal is less than the second threshold, it is determined The audio signal is a noise signal, and the result of the positive comparison is logically false.

A2. Compare the received audio signal with a preset third threshold, determine whether the audio signal is a voice signal, and get the reverse comparison result; where the third threshold is the maximum value of the reverse voice signal, which depends on the microphone Sensitivity, and the acquisition of different sound pressure noises under this sensitivity, the specific setting work should be combined with acoustic theory and experimental statistics. When comparing the received audio signal with the preset third threshold, if the audio signal is less than the third threshold, the audio signal is determined to be a voice signal, and the reverse comparison result is logically true; if the audio signal is greater than the third threshold , It is determined that the audio signal is a noise signal, and the result of the reverse comparison is obtained as a logical false.

A3. Perform logical processing on the result of the forward comparison and the result of the reverse comparison to determine whether the audio signal is a voice signal.

In the embodiment of the present invention, it is determined whether the received audio signal is a voice signal by performing logical OR processing on the forward comparison result and the reverse comparison result. When either the forward comparison result or the reverse comparison result is logically true, the result of the logical or processing is logically true, the audio signal is judged to be a voice signal, and the output is logically true; when the forward comparison result and the reverse comparison result When both are false, the result of the logical OR processing is logical false, the audio signal is judged to be a noise signal, and the logical false is output.

A4. Perform logic processing on the result of the logic processing and the denoising control signal generated last time to generate a trigger signal for effective value detection.

In the embodiment of the present invention, the logic processing result is logically ORed with the denoising control signal generated last time. When any one of the logic processing result or the denoising control signal generated last time is logically true, Then it is determined that the audio signal needs to be detected by the effective value, and the output trigger signal of the effective value detection is logically true; when the logic processing result and the previously generated noise reduction control signal are both logically false, it is determined that the audio signal does not need to be detected. Perform effective value detection, and the output trigger signal for effective value detection is logical false.

In order to improve the processing accuracy of the audio signal and reduce the error when the amplitude of the audio signal is small, in another embodiment of the present invention, before judging whether the received audio signal is a voice signal, the method further includes the following steps :

Perform selective pre-amplification processing on the received audio signal.

B. Perform effective value detection on the audio signal to generate an output signal that reflects the average power of the audio signal. Since the specific implementation process of detecting the effective value of the audio signal belongs to the prior art, it will not be repeated here.

C. No effective value detection is performed on the audio signal, and an output signal with an inherent initial value is maintained. The inherent initial value is used to reflect the average power of the noise signal in the audio signal.

In the embodiment of the present invention, by detecting the effective value of the voice signal in the audio signal, the output of an inherent initial value is maintained in the noise segment, so that in the specific circuit design, on the one hand, the effective value detection part can be prevented. In the detection of the delay at the beginning of the average power of the voice signal, that is, the output signal with the effective value detection is smaller than the true value. On the other hand, the output can be kept at a constant value in the presence of noise, which can save power consumption.

In step S102, the output signal reflecting the average power of the audio signal is compared with a first threshold to generate a noise cancellation control signal.

In the embodiment of the present invention, according to the difference between the average power of the voice signal and the average power of the noise signal, the critical value between the average power of the voice signal and the average power of the noise signal is set, and the critical value is taken as the first A threshold value. By comparing the output signal used to reflect the average power of the audio signal with the first threshold value, the voice signal and the noise signal in the audio signal can be distinguished, thereby generating the noise canceling control for controlling the noise canceling process Signal.

In order to achieve a more comfortable voice signal, in another embodiment of the present invention, the output signal reflecting the average power of the audio signal is compared with the first threshold, and the step of generating the noise cancellation control signal specifically includes:

A. Compare the output signal used to reflect the average power of the audio signal with the fourth threshold, and extract the control signal of the effective voice signal;

The fourth threshold is mainly used to detect valid voice signals, that is, to set the noise threshold. The specific setting depends on the sensitivity of the microphone and the collection of different sound pressure noises under this sensitivity. The specific setting work should be combined with acoustic theory and experimental statistics. In the embodiment of the present invention, when a valid voice signal is detected, the output is logically true, and when a valid voice signal is not detected, the output is logically false.

B. Compensate the extracted control signal of the effective voice signal to obtain the control signal of the effective voice signal after compensation processing;

C. Compare the output signal used to reflect the average power of the audio signal with the fifth threshold to extract the control signal of the super-large signal; the fifth threshold is mainly used to detect effective voice signals, that is, to set the noise threshold. The specific setting depends on the sensitivity of the microphone and the collection of different sound pressure noises under this sensitivity. The specific setting work should be combined with acoustic theory and experimental statistics. In the embodiment of the present invention, when a super-large speech signal is detected, the output is logically true, and when the super-large speech signal is not detected, the output is logically false.

D. Perform exclusive OR processing on the control signal of the effective voice signal after the compensation process and the control signal of the extracted super-large signal to generate a noise-removing control signal.

In the embodiment of the present invention, when the control signal of the effective voice signal after compensation processing and the control signal of the extracted super-large signal are XORed, if the logical value of the control signal of the effective voice signal and the control signal of the super-large signal are different When the same, the output logic is true, when the same, the output logic is false. For example, when the control signal of the effective voice signal and the control signal of the extracted super-large signal are both logically true, it means that the effective voice signal is detected, and the super-large voice signal is detected at the same time. After the exclusive OR processing, the generated noise canceling control signal is logical False; when the control signal of the effective voice signal and the control signal of the extracted super-large signal are both logically false, it means that the effective voice signal is not detected, and the super-large voice signal is not detected at the same time, the noise elimination control generated after the exclusive OR processing The signal is still logically false; when the control signal of the effective voice signal is logically true, and the extracted control signal of the super-large signal is all logically false, it means that the effective voice signal is detected, and the super-large voice signal is not detected at the same time, after XOR processing , The generated noise control signal is logically true; when the control signal of the effective voice signal is logically false, and the extracted control signal of the super signal is logically true, it means that no valid speech signal is detected, and no super speech is detected at the same time After the signal, XOR is processed, the noise cancellation control signal generated is logically true.

In step S103, under the control of the noise cancellation control signal, the noise signal in the audio signal is eliminated, and the speech signal is amplified.

In the embodiment of the present invention, when the denoising control signal is logically true, the audio signal is amplified, and when the denoising control signal is logically false, the audio signal is eliminated, thereby eliminating the voice background noise and simultaneously amplifying Voice signal, realize the elimination of voice background noise. Among them, under the control of the denoising control signal, the noise signal in the audio signal is eliminated, and there are many ways to amplify the voice signal. For example, under the control of the denoising control signal, the audio signal is directly amplified and preset Or prohibit the output of the audio signal; under the control of the denoising control signal, the audio signal can be processed in the same phase or reverse phase to eliminate the noise signal and amplify the voice signal. Of course, it is also possible to use other methods to amplify and cancel the audio signal according to the noise canceling control signal, which will not be described one by one here.

As the received audio signal will inevitably have excessive audio frequency, if the excessive audio signal is not processed, when the audio signal is subsequently enhanced, the comfort of the listener will be reduced. In order to improve the comfort of the listener, In another embodiment of the present invention, before step S103, the method further includes the following steps:

The output signal reflecting the average power of the audio signal is compared with the sixth threshold to generate an attenuation control signal. The attenuation control signal is used to control the inverted amplification of the received audio signal in different proportions, so as to appropriately reduce the excessively large audio signal.

The sixth threshold is preset to allow the maximum power of the audio signal. In the embodiment of the present invention, when the output signal used to reflect the average power of the audio signal is greater than the sixth threshold, the output attenuation control signal is logically true, and the attenuation control signal is used to control a certain proportion of the received audio signal. Attenuation, to appropriately reduce the audio signal that is too large; when the output signal used to reflect the average power of the audio signal is less than or equal to the sixth threshold, the output attenuation control signal is logically false, and the attenuation control signal is used for the audio signal Perform constant-amplitude inverted amplification, that is, do not process the amplitude of the audio signal.

Under the control of the attenuation control signal, the received audio signal is inverted and amplified in different proportions to appropriately reduce the excessive audio signal.

In the embodiment of the present invention, when the volume of the audio signal is in the normal range, the attenuation control signal controls the equal-amplitude inverted amplification of the audio signal, that is, the amplitude of the audio signal is not processed, and the inverted amplified signal is obtained; When the volume of the audio signal exceeds the normal range, the attenuation control signal controls the attenuation of the excessive audio signal in a certain proportion, so that the excessive audio signal is appropriately reduced, and the inverted and amplified signal is obtained.

At this time, under the control of the denoising control signal, the inverted amplified audio signal is eliminated or amplified to eliminate the noise signal in the inverted amplified audio signal, and the inverted amplified audio signal is amplified Voice signal.

The second figure shows the structure of the voice background noise elimination device provided by the embodiment of the present invention. For ease of description, only the parts related to the embodiment of the present invention are shown. in:

The effective value detection unit (2) detects the effective value of the received audio signal to obtain an output signal used to reflect the average power of the audio signal. The effective value detection unit (2) includes a voice signal judgment circuit (22), an effective value detection control circuit (23) and an effective value detection circuit (24). in:

The voice signal judgment circuit (22) judges whether the received audio signal is a voice signal. In the embodiment of the present invention, in order to improve the accuracy of judgment, the speech signal judgment circuit (22) includes a forward speech signal judgment module (221), a reverse speech signal judgment module (222), and a first logic processing module. Group (223).

The forward voice signal judgment module (221) compares the received audio signal with a second threshold, judges whether the audio signal is a voice signal, and obtains a positive comparison result;

The second threshold is the minimum value of the forward voice signal. The specific setting depends on the sensitivity of the microphone and the collection of different sound pressure noises under this sensitivity. The specific setting work should be combined with acoustic theory and experimental statistics. When comparing the received audio signal with the second threshold, when the audio signal is greater than the second threshold, it is determined that the audio signal is a voice signal, and the positive comparison result is logically true; when the audio signal is less than the second threshold, it is determined The audio signal is a noise signal, and the result of the positive comparison is logically false.

The reverse speech signal judgment module (222) compares the received audio signal with a preset third threshold, judges whether the audio signal is a speech signal, and obtains a reverse comparison result;

The third threshold is the maximum value of the reverse speech signal, which depends on the sensitivity of the microphone and the collection of different sound pressure noises under this sensitivity. The specific setting work should be combined with acoustic theory and experimental statistics. . When comparing the received audio signal with the preset third threshold, if the audio signal is less than the third threshold, the audio signal is determined to be a voice signal, and the reverse comparison result is logically true; if the audio signal is greater than the third threshold , It is determined that the audio signal is a noise signal, and the result of the reverse comparison is obtained as a logical false.

The first logic processing module (223) performs logic processing on the forward comparison result and the reverse comparison result, and judges whether the received audio signal is a voice signal.

In the embodiment of the present invention, it is determined whether the received audio signal is a voice signal by performing logical OR processing on the forward comparison result and the reverse comparison result. When either the forward comparison result or the reverse comparison result is logically true, the result of the logical or processing is logically true, the audio signal is judged to be a voice signal, and the output is logically true; when the forward comparison result and the reverse comparison result When both are false, the result of the logical OR processing is logical false, the audio signal is judged to be a noise signal, and the logical false is output.

The effective value detection control circuit (23) performs logical processing between the logic processing result output by the first logic processing module (223) and the previous noise canceling control signal generated by the noise canceling control signal generating unit (3) to generate the effective value detection Trigger signal to control whether to detect the effective value of the audio signal.

In the embodiment of the present invention, the logic processing result is logically ORed with the previous noise cancellation control signal generated by the noise cancellation control signal generating unit (3), when the logic processing result or the previous noise cancellation control signal is When any one is logically true, it is determined that effective value detection of the audio signal is required; when the logical processing result and the previous noise canceling control signal are both logically false, it is determined that the effective value detection of the audio signal is not required.

The effective value detection circuit (24) performs effective value detection on the audio signal under the control of the effective value detection control circuit (23) to generate an output signal that reflects the average power of the audio signal, or does not perform effective value detection on the audio signal, Maintain an inherent initial value of the output signal. The inherent initial value is used to reflect the average power of the noise signal in the audio signal.

In the embodiment of the present invention, by detecting the effective value of the voice signal in the audio signal, the output of an inherent initial value is maintained in the noise segment, so that in the specific circuit design, on the one hand, the effective value detection part can be prevented. In the detection of the delay at the beginning of the average power of the voice signal, that is, the output signal with the effective value detection is smaller than the true value. On the other hand, the output can be kept at a constant value in the presence of noise, which can save power consumption.

In order to improve the processing accuracy of the audio signal and reduce the error when the amplitude of the audio signal is small, in another embodiment of the present invention, the device further includes a signal pre-amplification circuit (21). The input end of the signal pre-amplification circuit (21) is connected with the audio acquisition unit (1), and the output ends are respectively connected with the forward voice signal judgment module (221), the reverse voice signal judgment module (222) and the effective value detection The circuit (24) is connected, and the signal pre-amplification circuit (21) performs selective pre-amplification processing on the received audio signal. At this time, the forward voice signal judgment module (221) compares the audio signal output by the signal pre-amplification circuit (21) with the second threshold to determine whether the audio signal is a voice signal, and obtain the forward comparison result; reverse voice signal The judgment module (222) compares the audio signal output by the signal pre-amplification circuit (21) with the preset third threshold to determine whether the audio signal is a voice signal, and obtain the reverse comparison result; the effective value detection circuit (24) is Under the control of the effective value detection control circuit (23), the effective value detection of the audio signal output by the signal preamplifier circuit (21) is performed to generate an output signal used to reflect the average power of the audio signal. In another embodiment of the present invention, under the control of the effective value detection control circuit (23), no effective value detection is performed on the audio signal, and an output signal with a inherent initial value is maintained.

Because the speakers environment is generally more complex, there are multiple sources of sound besides the speaker, such as the voices of other speakers around, the sound of surrounding vehicles, etc. Therefore, the received audio signal includes not only the speakers voice Signals also include noise signals from other sound sources around the speaker.

In the embodiment of the present invention, the received audio signal may be a collected audio signal, or may be an audio signal transmitted from another device. When the received audio signal is a collected audio signal, the device also includes an audio collection unit (1). The audio collection unit (1) collects audio signals, where the audio signals include voice signals and noise signals. Please refer to the third figure for the specific circuit structure of the audio acquisition unit (1). I will not go into details here.

The noise cancellation control signal generation unit (3) compares the output signal generated by the effective value detection unit (3) and used to reflect the average power of the audio signal with the first threshold to generate the noise cancellation control signal. The denoising control signal is used to control the denoising amplifying unit to perform denoising processing on the audio signal. The first threshold refers to a predetermined threshold between the average power of the voice signal and the average power of the noise signal. By comparing the output signal used to reflect the average power of the audio signal with the first threshold, the voice signal and the noise signal in the audio signal can be distinguished, thereby generating a signal for controlling the denoising amplification unit to denoise the audio signal Processed denoising control signal. The noise cancellation control signal generation unit (3) includes an effective voice signal comparison module (31), a super-large voice signal comparison module (32), a control signal compensation module (33), and a second logic processing module (34). in:

The effective voice signal comparison module (31) compares the output signal generated by the effective value detection unit (2) for reflecting the average power of the audio signal with the fourth threshold, and extracts the control signal of the effective voice signal;

The fourth threshold is mainly used to detect valid voice signals, that is, to set the noise threshold. The specific setting depends on the sensitivity of the microphone and the collection of different sound pressure noises under this sensitivity. The specific setting work should be combined with acoustic theory and experimental statistics. In the embodiment of the present invention, when a valid voice signal is detected, the output is logically true, and when a valid voice signal is not detected, the output is logically false.

The control signal compensation module (33) compensates the control signal of the effective voice signal extracted by the effective voice signal comparison module (31) to obtain the control signal of the effective voice signal after compensation processing;

The super voice signal comparison module (32) compares the output signal generated by the effective value detection unit (2) for reflecting the average power of the audio signal with the fifth threshold, and extracts the control signal of the super signal;

The fifth threshold is mainly used to detect valid voice signals, that is, to set the noise threshold. The specific setting depends on the sensitivity of the microphone and the collection of different sound pressure noises under this sensitivity. The specific setting work should be combined with acoustic theory and experimental statistics. In the embodiment of the present invention, when a super-large speech signal is detected, the output is logically true, and when the super-large speech signal is not detected, the output is logically false.

The second logic processing module (34) performs exclusive OR processing on the control signal of the effective voice signal after the compensation process and the control signal of the extracted super-large signal to generate a noise canceling control signal.

Under the control of the noise canceling control signal generated by the noise canceling control signal generating unit (3), the noise canceling amplifying unit (4) eliminates the noise signal in the audio signal and amplifies the voice signal.

The denoising amplifying unit (4) under the control of the denoising control signal, eliminates the noise signal in the audio signal, and there are many ways to amplify the voice signal. For example, under the control of the denoising control signal, directly Amplify the audio signal by a preset time, or prohibit the output of the audio signal; it is also possible to perform in-phase or reverse-phase processing on the audio signal under the control of the noise canceling control signal to eliminate the noise signal and amplify the voice signal. Of course, it is also possible to use other methods to amplify the audio signal according to the denoising control signal, and to cancel the audio signal. Here, only a specific structure of the denoising amplifying unit (4) is given, which includes a controllable inverting The inverter (41), the first inverting follower (42), the second inverting follower (43), the inverting adder (44) and the low-pass filter (45).

As the received audio signal will inevitably have excessive audio frequency, if the excessive audio signal is not processed, when the audio signal is subsequently enhanced, the comfort of the listener will be reduced. In order to improve the comfort of the listener, In another embodiment of the present invention, the device further includes an attenuation control signal generating unit (5) and an audio controllable attenuation unit (6). in:

The attenuation control signal generation unit (5) compares the output signal generated by the effective value detection unit (2) and used to reflect the average power of the audio signal with a sixth threshold to generate an attenuation control signal. The attenuation control signal is used to control the audio controllable attenuation unit (6) to perform inverted amplification of different proportions on the received audio signal, so as to appropriately reduce the excessively large audio signal.

The sixth threshold is preset to allow the maximum power of the audio signal. In the embodiment of the present invention, when the output signal used to reflect the average power of the audio signal is greater than the sixth threshold, the output attenuation control signal is logically true; when the output signal used to reflect the average power of the audio signal is less than or equal to the first When the threshold is six, the output attenuation control signal is logically false.

The audio controllable attenuation unit (6), under the control of the attenuation control signal, performs inverse amplification of the received audio signal in different proportions to appropriately reduce the excessive audio signal.

In the embodiment of the present invention, when the volume of the audio signal is in the normal range, the attenuation control signal controls the equal-amplitude inverted amplification of the audio signal, that is, the amplitude of the audio signal is not processed, and the inverted amplified signal is obtained; When the volume of the audio signal exceeds the normal range, the attenuation control signal controls the attenuation of the excessive audio signal in a certain proportion, so that the excessive audio signal is appropriately reduced, and the inverted and amplified signal is obtained.

At this time, under the control of the denoising control signal, the denoising amplifying unit (2) cancels or amplifies the audio signal output by the audio controllable attenuation unit (6) to eliminate the noise in the inverted and amplified audio signal. Signal, amplify the voice signal in the inverted and amplified audio signal.

The third figure shows the circuit principle of the audio acquisition unit (1) provided by the embodiment of the present invention. The audio acquisition unit (1) includes a voltage divider circuit, a DC blocking circuit, and an inverting follower. The microphone 1a is composed of a resistor R1, the DC blocking circuit is composed of a capacitor C1, and the inverting follower is composed of an operational amplifier U1, a resistor R2, and a resistor R3. The microphone is an omnidirectional microphone, such as a conventional microphone in a communication device such as a mobile phone, which is used to sense external audio signals and convert the sound signals into electrical signals. The electrical signal obtained by the microphone is subjected to direct-cut processing through the direct-cutting circuit formed by the first capacitor C1, and the electrical signal is converted into an alternating current signal, and then the signal is output through an inverting follower<img file="TWI413112B_D0001.tif" he="16" id="i0002" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="19" />。

The fourth figure shows the circuit principle of the signal pre-amplification circuit (21) provided by the embodiment of the present invention. The signal pre-amplification circuit (21) includes an operational amplifier U7, a resistor R16 connected to one of the input terminals of the operational amplifier U7, and a resistor R17 connected across the input terminal and the output terminal of the operational amplifier. The signal pre-amplification circuit (21) realizes the output signal of the signal acquisition unit (1) by adjusting the ratio of the resistor R16 and the resistor R17 according to the processing accuracy actually required by the system<img file="TWI413112B_D0001.tif" he="14" id="i0004" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="16" />Perform selective pre-amplification processing to get the pre-amplified signal<img file="TWI413112B_D0003.tif" he="14" id="i0006" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="16" />。

The fifth figure shows the circuit principle of the forward speech signal judgment module (221) and the reverse speech signal judgment module (222) provided by an embodiment of the present invention.

The forward voice signal judgment module (221) and the reverse voice signal judgment module (222) both include a comparator U8 and a Schmitt inverter (U9, U10). The comparator U8 pre-amplifies the signal (21). ) The processed audio signal<img file="TWI413112B_D0003.tif" he="14" id="i0008" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="16" />Compare with the preset first threshold, and then use Schmitt inverters (U9, U10) to shape the noise to obtain the comparison result signal<img file="TWI413112B_D0005.tif" he="13" id="i0010" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="14" />; The audio signal processed by the signal pre-amplification circuit (21)<img file="TWI413112B_D0003.tif" he="14" id="i0012" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="16" />Compare with the preset second threshold, and then use Schmitt inverters (U9, U10) to shape the noise to obtain the comparison result signal<img file="TWI413112B_D0007.tif" he="13" id="i0014" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="16" />。

The sixth figure shows the circuit principle of the first logic processing module (223) provided by the embodiment of the present invention.

The first logic processing module (223) is composed of a logic OR gate U11, and the two input signals of the logic OR gate U11 are the output signals of the forward voice signal judgment module (221).<img file="TWI413112B_D0005.tif" he="13" id="i0016" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="14" />And the output signal of the reverse voice signal judgment module (222)<img file="TWI413112B_D0007.tif" he="13" id="i0018" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="15" />, When the output signal of the forward voice signal judgment module (221)<img file="TWI413112B_D0005.tif" he="13" id="i0020" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="14" />And the output signal of the reverse voice signal judgment module (222)<img file="TWI413112B_D0007.tif" he="13" id="i0022" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="15" />When any one of them is true, that is, when any one of the forward speech signal judgment module (221) and the reverse speech signal judgment module (222) judges that the audio signal is a speech signal, it will be processed by the logic or gate U11 , Its output signal<img file="TWI413112B_D0012.tif" he="16" id="i0024" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="19" />If it is true, that is, after processing by the logic OR gate U11, it is determined that the audio signal is a voice signal; otherwise, it is determined that the audio signal is a noise signal.

The seventh figure shows the circuit principle of the effective value detection control circuit (23) and the effective value detection circuit (24) provided by the embodiment of the present invention.

The effective value detection control circuit (23) includes a logical OR gate U13 and a two-to-one selection switch S3. The two input terminals of the logic OR gate U13 are respectively connected to the output terminal of the first logic processing module (223), and the other input terminal is connected to the second logic processing module ( 34) The output terminal is connected, and the output signal of the logic OR gate U13 is used as the control signal of the two-to-one selection switch S3. The effective value detection circuit (24) is controlled by the two-to-one selection switch S3 to detect the effective value of the audio signal. For the output signal reflecting the average power of the audio signal, or without detecting the effective value of the audio signal, it directly maintains the output of an inherent initial value V1. The working principle of this circuit is as follows:

The logic OR gate U13 connects the output signal of the first logic processing module (223)<img file="TWI413112B_D0012.tif" he="16" id="i0026" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="19" />And the output signal of the second logic processing module (34)<img file="TWI413112B_D0014.tif" he="17" id="i0028" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="17" />Perform or process to obtain the control signal of the second-to-one selection switch S3<img file="TWI413112B_D0015.tif" he="16" id="i0030" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />,control signal<img file="TWI413112B_D0015.tif" he="16" id="i0032" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />Control the output signal of the signal pre-amplifier circuit (21)<img file="TWI413112B_D0003.tif" he="14" id="i0034" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="16" />Switch between and the preset inherent initial value V1 to get the output signal<img file="TWI413112B_D0018.tif" he="15" id="i0036" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="16" />, Through the output signal<img file="TWI413112B_D0018.tif" he="15" id="i0038" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="16" />Control the output signal of the effective value detection circuit (24) to the signal pre-amplification circuit (21)<img file="TWI413112B_D0003.tif" he="14" id="i0040" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="16" />Perform effective value detection and generate an output signal DD for reflecting the average power of the audio signal, or do not perform effective value detection on the audio signal, but directly maintain the output of an inherent initial value V1.

The eighth figure shows the circuit principle of the effective voice signal comparison module (31) and the super-large voice signal comparison module (32) provided by the embodiment of the present invention.

The effective voice signal comparison module (31) includes a comparator U15 and Schmitt inverters (U17, U18). The comparator U15 compares the output signal DD of the effective value detection circuit (24) with a preset fourth threshold. Compare to extract the control signal for the effective voice signal and output the control signal for the effective voice<img file="TWI413112B_D0021.tif" he="15" id="i0042" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="17" />. The fourth threshold is mainly used to detect valid voice signals, that is, to set the noise threshold. The specific setting depends on the sensitivity of the microphone and the collection of different sound pressure noises under this sensitivity. The specific setting work should be combined with acoustic theory and experimental statistics. During the comparison, when the signal DD is greater than the fourth threshold, the output of the effective voice signal comparison module (31) is logically true, representing a voice signal. When it is less than the fourth threshold, the output logic of the effective voice signal comparison module (31) is false, representing a noise signal.

The super-large voice signal comparison module (32) includes a comparator U16 and Schmitt inverters (U19, U20). The comparator U16 compares the output signal DD of the effective value detection circuit (24) with the preset fifth threshold. Compare, extract the control signal for the super-large signal, and output the control signal of the super-large signal<img file="TWI413112B_D0022.tif" he="16" id="i0044" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="19" />. In the process of communication, it is inevitable that there will be wind noise in the communication environment. The sudden oversized noise will give the receiver (listener) a harsh sound. In this case, pass the oversized voice signal comparison module (32) The control signal is extracted for the super-large signal, so that the noise-removing amplifying unit (4) can eliminate the super-large signal and improve the hearing comfort of the listener.

The ninth figure shows the circuit principle of the control signal compensation module (33) provided by the embodiment of the present invention.

The control signal compensation module (33) includes a multivibrator U21 and an OR gate U22. The multivibrator U21 detects the falling edge of the output pulse of the effective voice signal comparison module (31). Once the falling edge is detected, the multivibrator outputs a pulse signal with a unique width. After the or gate U22, the effective voice The output pulse of the signal comparison module (31) is compensated to widen this unique pulse width, and the effective voice control signal after compensation processing is obtained.<img file="TWI413112B_D0023.tif" he="17" id="i0046" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="18" />. In this way, at the end of the voice, the loss of the voice can be reduced, and the voice can be restored with high quality.

The tenth figure shows the circuit principle of the second logic processing module (34) provided by the embodiment of the present invention.

The second logic processing module (34) is composed of a logic exclusive OR gate U23. The output signal of the control signal compensation module (33)<img file="TWI413112B_D0023.tif" he="17" id="i0048" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="18" />Compare with the output signal of the super-large voice signal module (32)<img file="TWI413112B_D0022.tif" he="16" id="i0050" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="19" />They are respectively sent to the input terminals of the second logic processing module (34), and the two signals are subjected to exclusive OR logic to form a noise canceling control signal<img file="TWI413112B_D0026.tif" he="17" id="i0052" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="19" />, The noise cancellation control signal<img file="TWI413112B_D0026.tif" he="17" id="i0054" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="19" />It is used for controlling the denoising amplification unit (4) to denoise the audio signal processed by the audio controllable attenuation unit (6).

Figure 11 shows the circuit principle of the attenuation control signal generating unit (5) provided by the embodiment of the present invention.

The attenuation control signal generation unit (5) is composed of a comparator U12, one of the input signals of the comparator U12 is the output signal DD output by the effective value detection circuit (24) for reflecting the average power of the audio signal, and the other input The signal is the preset sixth threshold, and the comparator U12 compares the output signal DD with the preset sixth threshold to generate an attenuation control signal<img file="TWI413112B_D0028.tif" he="18" id="i0056" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />. The attenuation control signal<img file="TWI413112B_D0028.tif" he="18" id="i0058" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />It is used for controlling the audio controllable attenuation unit (6) to perform inverting amplification of different proportions on the audio signal output by the audio collecting unit (1). In the embodiment of the present invention, when the output signal used to reflect the average power of the audio signal is greater than the preset sixth threshold, the generated attenuation control signal<img file="TWI413112B_D0028.tif" he="18" id="i0060" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />, Control the audio controllable attenuation unit (6) to perform equal amplitude inverted amplification of the audio signal, that is, do not attenuate the amplitude of the audio signal; when the output signal used to reflect the average power of the audio signal is less than or equal to the preset first Attenuation control signal generated at six thresholds<img file="TWI413112B_D0028.tif" he="18" id="i0062" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />Control the audio controllable attenuation unit (6) to attenuate the excessive audio signal in a certain proportion, so as to appropriately reduce the excessive audio signal.

Figure 12 shows the circuit principle of the audio controllable attenuation unit (6) provided by the embodiment of the present invention.

The audio controllable attenuation unit (6) includes an operational amplifier U2, a control switch S1, and resistors R3, R4, and R5. The resistor R3 and the resistor R4 are connected in series with the input end of the operational amplifier U2, the control switch S1 is connected in parallel to both ends of the resistor R3, and the resistor R5 is connected across the input and output ends of the operational amplifier U2. The control signal of the control switch S1 comes from the attenuation control signal generated by the attenuation control signal generating unit (5)<img file="TWI413112B_D0028.tif" he="18" id="i0064" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />, Attenuation control signal<img file="TWI413112B_D0028.tif" he="18" id="i0066" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />Control the on and off of the control switch, so as to realize the audio signal output from the audio acquisition unit (1)<img file="TWI413112B_D0001.tif" he="18" id="i0068" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="21" />Perform inverted amplification of different proportions to obtain the inverted amplified signal<img file="TWI413112B_D0035.tif" he="17" id="i0070" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />. In the embodiment of the present invention, when the volume of the audio signal is in the normal range, the control signal is attenuated<img file="TWI413112B_D0028.tif" he="18" id="i0072" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />Control the audio controllable attenuation unit (6) to perform equal amplitude inverted amplification of the audio signal, that is, do not process the amplitude of the audio signal, and obtain the inverted amplified signal<img file="TWI413112B_D0035.tif" he="18" id="i0074" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="19" />; When the volume of the audio signal exceeds the normal range, attenuate the control signal<img file="TWI413112B_D0028.tif" he="18" id="i0076" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />Control the audio controllable attenuation unit (6) to attenuate the excessive audio signal in a certain proportion, so as to appropriately reduce the excessive audio signal, and obtain the inverted and amplified signal<img file="TWI413112B_D0035.tif" he="18" id="i0078" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />。

Figure 13 shows the circuit principle of the controllable inverter (41) provided by the embodiment of the present invention.

The two input ends of the controllable inverter (41) are respectively connected with the output ends of the audio controllable attenuation unit (6) and the second logic processing module (34). The controllable inverter (41) includes an op amp U3, resistors R6, R7, and a two-choice selection switch S2. The resistor R6 is connected to one of the input terminals of the op amp U3, and the resistor R7 is connected across the input of the op amp U3 Terminal and output terminal, select one of the two selection switch S2 in the noise canceling control signal<img file="TWI413112B_D0026.tif" he="17" id="i0080" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="19" />Under the control of the inverted and amplified signal<img file="TWI413112B_D0035.tif" he="17" id="i0082" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="18" />Perform in-phase or reverse-phase processing to get the signal<img file="TWI413112B_D0042.tif" he="16" id="i0084" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="17" />. When performing in-phase processing, enhance the inverted and amplified signal<img file="TWI413112B_D0035.tif" he="18" id="i0086" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />, Get the signal<img file="TWI413112B_D0042.tif" he="16" id="i0088" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="17" />; When the inversion process is performed, the noise is eliminated and the signal is obtained<img file="TWI413112B_D0042.tif" he="16" id="i0090" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="17" />。

The fourteenth and fifteenth figures show the circuit principles of the first inverting follower (42) and the second inverting follower (43) provided by the embodiments of the present invention.

The input terminal of the first inverting follower (42) is connected with the output terminal of the audio controllable attenuation unit (6), and the output terminal is connected with the input terminal of the inverting adder (41). The first inverting follower (42) includes an operational amplifier U4, a resistor R8 connected to one of the input terminals of the operational amplifier U4, and a resistor R9 connected across the input terminal and the output terminal of the operational amplifier U4. The input signal is the output signal of the audio controllable attenuation unit (6)<img file="TWI413112B_D0035.tif" he="18" id="i0092" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />,output signal<img file="TWI413112B_D0047.tif" he="18" id="i0094" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />; The input terminal of the second inverting follower (43) is connected with the controllable inverter (41), and the output terminal is connected with the input of the inverting adder. The second inverting follower (43) includes an operational amplifier U5, a resistor R10 connected to one of the input terminals of the operational amplifier U5, and a resistor R11 connected across the input terminal and the output terminal of the operational amplifier U5. Its input signal is the output signal of the inverting adder (41)<img file="TWI413112B_D0042.tif" he="18" id="i0096" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="20" />,output signal<img file="TWI413112B_D0049.tif" he="19" id="i0098" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="21" />。

Figure 16 shows the circuit principle of the inverting adder (44) provided by the embodiment of the present invention.

The two input ends of the inverting adder (44) are respectively connected to the output ends of the first inverting follower (42) and the second inverting follower (43), which includes an operational amplifier U6 and an operational amplifier U6. The resistor R12 connected to one input terminal and the resistor R13 connected to the other input terminal of the operational amplifier U6 are connected across the input terminal where the resistor R13 of the operational amplifier U6 is located and the resistor R14 of the output terminal of the operational amplifier U6. The two input signals of the inverting adder (44) are the input signals of the first inverting follower (42) respectively<img file="TWI413112B_D0047.tif" he="19" id="i0100" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="21" />, The output signal of the second inverting follower (43)<img file="TWI413112B_D0049.tif" he="19" id="i0102" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="21" />,output signal<img file="TWI413112B_D0052.tif" he="20" id="i0104" img-content="drawing" img-format="jpg" inline="yes" orientation="portrait" wi="22" />。

Figure 17 shows the circuit principle of the low-pass filter (45) provided by the embodiment of the present invention.

The input end of the low-pass filter is connected to the output end of the inverting adder (44). It includes a first resistor R15 and a capacitor C2. The low-pass filter (44) filters out the extra noise outside the voice band generated in the device, and retains the frequency components in the voice band.

In the embodiment of the present invention, by detecting the effective value of the received audio signal, the output signal reflecting the average power of the audio signal is obtained, and the output signal reflecting the average power of the audio signal is combined with the first threshold value. Compare, generate the noise cancellation control signal, carry out the cancellation processing on the noise signal in the audio signal under the control of the noise cancellation control signal, and carry out the amplification processing on the speech signal, so as to realize the cancellation of the speech background noise. At the same time, by comparing the output signal used to reflect the average power of the audio signal with the sixth threshold, an attenuation control signal is generated, and under the control of the attenuation control signal, the received audio signal is inverted and amplified in different proportions to appropriately reduce Excessive audio signal improves the hearing comfort of the receiver.

In summary, this creation can indeed achieve the above-mentioned functions and purposes, so this creation should meet the requirements of a patent application, and an application should be filed in accordance with the law.

<p>(1)Input terminal and audio capture unit</p><p>(2)Valid value detection unit</p><p>(21)Signal pre-amplification circuit</p><p>(22)Speech signal judgment circuit</p><p>(221)Forward voice signal judgment module</p><p>(222)Reverse voice signal judgment module</p><p>(223)The first logic processing module</p><p>(23)effective value detection control circuit</p><p>(24)Valid value detection circuit</p><p>(3)Noise reduction control signal generation unit</p><p>(31)Effective voice signal comparison module</p><p>(32)Large voice signal comparison module</p><p>(33)Control signal compensation module</p><p>(34)Second logic processing module</p><p>(4)Noise reduction amplifier unit</p><p>(41)Controllable inverter</p><p>(42)The first inverting follower</p><p>(43)Second Inverting Follower</p><p>(44)Inverting adder</p><p>(45)Low Pass Filter</p><p>(5)Attenuation control signal generation unit</p><p>(6)Audio controllable attenuation unit</p>

The first figure is an implementation flowchart of a method for eliminating voice background noise provided by an embodiment of the present invention;

The second figure is a structural block diagram of a voice background noise elimination device provided by an embodiment of the present invention;

The third figure is a circuit schematic diagram of the audio acquisition unit provided by the embodiment of the present invention;

The fourth figure is a circuit schematic diagram of the signal pre-amplification circuit provided by the embodiment of the present invention;

The fifth figure is a circuit schematic diagram of the forward voice signal judgment module and the reverse voice signal judgment module provided by the embodiment of the invention;

The sixth figure is a circuit schematic diagram of the first logic processing module provided by an embodiment of the present invention;

The seventh diagram is a schematic circuit diagram of the effective value detection control circuit and the effective value detection circuit provided by the embodiment of the present invention;

The eighth figure is a schematic circuit diagram of the effective voice signal comparison module and the super-large voice signal comparison module provided by the embodiment of the present invention;

The ninth figure is a schematic circuit diagram of the control signal compensation module provided by the embodiment of the present invention;

Figure 10 is a schematic circuit diagram of the second logic processing module provided by an embodiment of the present invention;

Figure 11 is a circuit schematic diagram of the attenuation control signal generating unit provided by the embodiment of the present invention;

Figure 12 is a circuit schematic diagram of an audio controllable attenuation unit provided by an embodiment of the present invention;

Figure 13 is a schematic circuit diagram of a controllable inverter provided by an embodiment of the present invention;

Figures fourteenth and fifteenth are schematic circuit diagrams of the first inverting follower and the second inverting follower provided by the embodiments of the present invention;

Figure 16 is respectively a circuit schematic diagram of an inverting adder provided by an embodiment of the present invention;

Figure 17 is a schematic circuit diagram of a low-pass filter provided by an embodiment of the present invention.