CN112929780B - Audio chip and earphone of noise reduction processing - Google Patents
Audio chip and earphone of noise reduction processing Download PDFInfo
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- CN112929780B CN112929780B CN202110251243.2A CN202110251243A CN112929780B CN 112929780 B CN112929780 B CN 112929780B CN 202110251243 A CN202110251243 A CN 202110251243A CN 112929780 B CN112929780 B CN 112929780B
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- 238000012545 processing Methods 0.000 title claims abstract description 41
- 230000009467 reduction Effects 0.000 title claims abstract description 20
- 210000000613 ear canal Anatomy 0.000 claims abstract description 46
- 230000005236 sound signal Effects 0.000 claims abstract description 42
- 238000005070 sampling Methods 0.000 claims abstract description 9
- 230000001052 transient effect Effects 0.000 claims description 11
- 238000000605 extraction Methods 0.000 claims description 10
- 230000015572 biosynthetic process Effects 0.000 claims description 9
- 238000003786 synthesis reaction Methods 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 6
- 230000007704 transition Effects 0.000 claims description 6
- 230000008569 process Effects 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 230000008859 change Effects 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 238000012546 transfer Methods 0.000 claims description 3
- 238000013139 quantization Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 2
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- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
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Abstract
The invention provides an audio chip and an earphone for noise reduction treatment; comprising the following steps: an audio processing circuit having a filter for processing the audio signal to produce a main audio signal having a first sampling frequency; an outboard microphone input for receiving an outboard microphone original signal indicative of ambient audio sounds; an ear canal microphone input for receiving an ear canal microphone raw signal that is closer to or located in the ear canal of a user; and an analog-to-digital converter for converting the outside microphone raw signal to an outside microphone signal and converting the ear canal microphone raw signal to an ear canal microphone signal; processing circuitry for receiving the outboard microphone signal and producing an anti-noise signal from the ear canal microphone signal; an output circuit for receiving the anti-noise signal, the main audio signal and producing a final output signal; the specific noise reduction processing can be realized based on different earphone use scenes, and the circuit is simple and the compatibility is good.
Description
Technical Field
The present invention relates to the field of audio output devices, and in particular, to an audio chip and an earphone for noise reduction.
Background
The sound quality of the earphone may be improved by measuring ambient noise using a microphone provided outside the earphone housing, and then generating an anti-noise signal using signal processing and combining into the output of the earphone to cancel the ambient noise. The effectiveness of ambient noise cancellation may be determined by the speaker output known by the measurement device at the speaker or in the ear canal, and the noise cancellation operation may be improved. The ideal output of the speaker is the main audio signal, with the noise cancellation signal canceling the ambient noise at the speaker location. To remove the primary audio signal from the ear canal microphone signal to identify remaining ambient noise, the filtered correct phase and amplitude of the primary audio signal may be subtracted from the ear canal microphone signal. However, the implementation of the above method is prone to errors when the main audio signal is not present, or when the user speaks, records, or sounds are generated inside the headset system.
Disclosure of Invention
In view of the foregoing drawbacks of the prior art, the present invention provides an audio chip with noise reduction, which is characterized by comprising: an audio processing circuit having a filter for processing the audio signal to produce a main audio signal having a first sampling frequency; an outboard microphone input for receiving an outboard microphone original signal indicative of ambient audio sounds; an ear canal microphone input for receiving an ear canal microphone raw signal that is closer to or located in the ear canal of a user; and an analog-to-digital converter for converting the outside microphone raw signal to an outside microphone signal and converting the ear canal microphone raw signal to an ear canal microphone signal; processing circuitry for receiving the outboard microphone signal and producing an anti-noise signal from the ear canal microphone signal; and the output circuit is used for receiving the anti-noise signal, the main audio signal and generating a final output signal.
Preferably, the output circuit includes an interpolator for receiving the anti-noise signal and producing a sampled anti-noise signal having a first sampling frequency; the interpolator includes a sign extension stage for extending the most significant bits of the anti-noise signal to avoid overflow.
Preferably, the output circuit further comprises a limiter, an adder and a low latency filter; the limiter is to provide clipping to reduce the number of bits in the up-sampled anti-noise signal; the adder is used for receiving and combining the main audio signal and the up-sampled anti-noise signal and generating a combined output signal; the low-latency filter is used to process the combined output signal and to generate a final output signal.
Preferably, the processing circuit comprises: the time-frequency conversion module is used for respectively converting the ear canal microphone signal and the outside microphone signal in the time domain into an ear canal microphone frequency domain sub-band signal and an outside microphone frequency domain sub-band signal; an extraction combining module for predicting a predicted clean audio signal in each of the ear canal microphone frequency domain sub-band signal and the outside microphone frequency domain sub-band signal, and obtaining an effective audio signal excluding noise sources by combining a lower frequency band of the predicted clean audio signal from the ear canal microphone frequency domain sub-band signal and a higher frequency band of the predicted clean audio signal from the outside microphone frequency domain sub-band signal; and the time domain synthesis module is used for converting the effective audio signal into an effective audio time domain signal through a subband synthesis process.
Preferably, the processing circuit further comprises a comparison module for comparing the effective audio time domain signal with the ear canal microphone signal, generating a noise feedback signal.
Preferably, the processing circuit further comprises an anti-noise signal module for combining the outboard microphone signal and the noise feedback signal to generate the anti-noise signal.
Preferably, the processing circuit further comprises a post-filtering module, which is used for reducing the residual noise of the effective audio signal and outputting the residual noise to the time domain synthesis module.
Preferably, the processing circuit further includes a transient noise reduction module, configured to detect transient noise from the ear canal microphone signal, and reduce the transient noise from the effective audio time domain signal and output the reduced transient noise to the comparison module.
Preferably, the extraction and combination module is further operable to update the weights of the linearly combined audio signals during the detected user speech.
Preferably, the extraction and combination module is further operable to calculate weights of the linearly combined audio signals to model a relative transfer function of noise signal contributions between the ear canal microphone and the outside microphone.
Preferably, the analog-to-digital converter uses a multi-bit analog modulator for receiving the analog signal forwarded to the input pins of the integrated circuit, converting the analog signal to an encoded multi-bit digital signal, and then presenting it as a multi-bit digital output in an output, feeding back the unit digital modulator.
Preferably, the single-bit digital modulator is configured to convert an input multi-bit digital signal into a single-bit digital signal, and the single-bit digital signal adopts a delta-sigma format.
Preferably, the unit digital signal is a serial stream of positive and negative pulses, which are converted multiples, the number of positive pulses increasing as the amplitude of the modulated analog signal increases.
Preferably, the analog-to-digital converter comprises at least one decimator or at least one interpolator coupled to receive the multi-bit digital signal and to generate a multi-bit digital output signal that transitions at a frequency that is less than or greater than the transition frequency, respectively; the decimator may maintain delta-sigma format; a rate change switch associated with the decimator or interpolator may modify the frequency to maintain compatibility.
The invention also provides an earphone which is provided with the audio chip for noise reduction treatment.
The audio chip and the earphone for noise reduction processing provided by the invention can automatically realize targeted noise reduction processing based on different earphone use scenes, and are simple in circuit and good in compatibility.
Drawings
Fig. 1 is a block diagram of an audio chip with noise reduction according to an embodiment of the present invention.
Fig. 2 is a block diagram of a processing circuit of an audio chip for noise reduction processing according to an embodiment of the present invention.
The device comprises an audio chip-100 for noise reduction, an external microphone input end-1, an auditory canal microphone input end-2, an audio processing circuit-3, an analog-to-digital converter-4, a processing circuit-5, an output circuit-6, an external microphone-7, an auditory canal microphone-8, an audio terminal-9, a loudspeaker-10, a time-frequency conversion module-11, an extraction combination module-12, a time domain synthesis module-13, a comparison module-14 and an anti-noise signal module-15.
Detailed Description
In order to solve the problem of poor noise reduction effect of the existing earphone system, the noise reduction processing audio chip and the earphone provided by the invention are realized by the following technical scheme:
Example 1:
The present embodiment provides an audio chip 100 for noise reduction, referring to fig. 1, including: an audio processing circuit 3 having a filter for processing the audio signal to generate a main audio signal having a first sampling frequency; an outer microphone input 1 for receiving an outer microphone raw signal indicative of ambient audio sounds; an ear canal microphone input 2 for receiving an ear canal microphone raw signal that is closer to or located in the ear canal of a user; and an analog-to-digital converter 4 for converting the outside microphone raw signal into an outside microphone signal and converting the ear canal microphone raw signal into an ear canal microphone signal; a processing circuit 5 for receiving the outside microphone signal and the ear canal microphone signal to generate an anti-noise signal; an output circuit 6 for receiving the anti-noise signal and producing a final output signal.
Specifically, the output circuit 6 includes an interpolator for receiving the anti-noise signal and producing a sampled anti-noise signal having a first sampling frequency; the interpolator includes a sign extension stage for extending the most significant bits of the anti-noise signal to avoid overflow.
Specifically, the output circuit 6 further includes a limiter, an adder, and a low-latency filter; the limiter is to provide clipping to reduce the number of bits in the up-sampled anti-noise signal; the adder is used for receiving and combining the main audio signal and the up-sampled anti-noise signal and generating a combined output signal; the low-latency filter is used to process the combined output signal and to generate a final output signal.
Specifically, referring to fig. 2, the processing circuit 5 includes: a time-frequency conversion module 11, configured to convert the ear canal microphone signal and the external microphone signal in the time domain into an ear canal microphone frequency domain subband signal and an external microphone frequency domain subband signal, respectively; an extraction combining module 12 for predicting a predicted clean audio signal in each of the ear canal microphone frequency domain sub-band signal and the outside microphone frequency domain sub-band signal and obtaining an effective audio signal excluding noise sources by combining a lower frequency band of the predicted clean audio signal from the ear canal microphone frequency domain sub-band signal and a higher frequency band of the predicted clean audio signal from the outside microphone frequency domain sub-band signal; the time domain synthesis module 13 is configured to convert the effective audio signal into an effective audio time domain signal through a subband synthesis process.
Specifically, the processing circuit 5 further comprises a comparing module 14 for comparing the effective audio time domain signal with the ear canal microphone signal, generating a noise feedback signal.
Specifically, the processing circuit 5 further comprises an anti-noise signal module 15 for combining the outer microphone signal and the noise feedback signal to generate an anti-noise signal.
Specifically, the processing circuit 5 further includes a post-filtering module, configured to reduce residual noise of the effective audio signal, and output the residual noise to the time domain synthesizing module 13.
Specifically, the processing circuit 5 further includes a transient noise reduction module, configured to detect transient noise from the ear canal microphone signal, and reduce the transient noise from the effective audio time domain signal and output the reduced transient noise to the comparison module 14.
In particular, the extraction and combination module 12 is also operable to update the weights of the linearly combined audio signals during the detected user speech.
In particular, the extraction and combination module 12 is further operable to calculate weights of linearly combined audio signals to model a relative transfer function of noise signal contributions between the ear canal microphone and the outside microphone.
In particular, the analog-to-digital converter 4 uses a multi-bit analog modulator for receiving the analog signal forwarded to the input pins of the integrated circuit, converting the analog signal into an encoded multi-bit digital signal, which is then presented as a multi-bit digital output in an output, feeding back the unit digital modulator.
Specifically, the single-bit digital modulator is used for converting an input multi-bit digital signal into a single-bit digital signal, and the single-bit digital signal adopts a delta-sigma format.
In particular, the unit digital signal is a serial stream of positive and negative pulses, which are converted by multiples, the number of positive pulses increasing as the amplitude of the modulated analog signal increases.
In particular, the analog-to-digital converter 4 comprises at least one decimator or at least one interpolator coupled to receive the multi-bit digital signal and to generate a multi-bit digital output signal that transitions at a frequency that is less than or greater than the transition frequency, respectively; the decimator may maintain delta-sigma format; a rate change switch associated with the decimator or interpolator may modify the frequency to maintain compatibility.
The use of a multi-bit quantizer in an analog modulator of delta-sigma format not only operates with reduced quantization step size, but more importantly, produces a greatly reduced quantization noise in the feedback signal. The digital decimation filter, which may be embodied on or separate from the integrated circuit, may accordingly be made simpler than the digital filter required to eliminate single bit quantizer noise. The reduced quantization noise can reduce the over-sampling rate, thereby reducing the working speed and complexity of the digital filter, and the filter has smaller volume and lower power consumption. The overhead of using a digital modulator is small. The components required for the digital modulator are readily available and readily implemented using various counters, accumulators, adders, etc. commonly known in digital circuit fabrication. The larger digital portion can be reduced to a minimum substrate area and the minimum noise can be attributed to the analog sampling portion of the mixed signal integrated circuit. The multi-bit quantizer in an analog modulator incurs minimal additional overhead compared to the single-bit quantizer in an analog modulator. Thus, the current combination of multi-bit analog modulators and single-bit digital modulators achieves the advantages of reduced quantization noise, minimal circuit overhead, and minimal complexity.
Example 2:
the embodiment provides an earphone, which has any one of the above noise reduction processing audio chips, and has the same performance, and will not be described again.
It should be noted that the above description of the present invention is further detailed in connection with the specific embodiments, and it should not be construed that the specific embodiments of the present invention are limited thereto, and those skilled in the art can make various improvements and modifications on the basis of the above-described embodiments while falling within the scope of the present invention.
Claims (2)
1. An audio chip for noise reduction processing, comprising:
An audio processing circuit having a filter for processing the audio signal to produce a main audio signal having a first sampling frequency; an outboard microphone input for receiving an outboard microphone original signal indicative of ambient audio sounds; an ear canal microphone input for receiving an ear canal microphone raw signal that is closer to or located in the ear canal of a user; the analog-to-digital converter is used for converting the original signal of the external microphone into an external microphone signal and converting the original signal of the auditory canal microphone into an auditory canal microphone signal; processing circuitry for receiving the outboard microphone signal and producing an anti-noise signal from the ear canal microphone signal; and an output circuit for receiving the anti-noise signal, the main audio signal, and producing a final output signal, the output circuit including an interpolator for receiving the anti-noise signal and producing a sampled anti-noise signal having a first sampling frequency; The interpolator includes a sign extension stage for extending the most significant bits of the anti-noise signal to avoid overflow, the output circuit further including a limiter, an adder, and a low latency filter; the limiter is to provide clipping to reduce the number of bits in the up-sampled anti-noise signal; the adder is used for receiving and combining the main audio signal and the up-sampled anti-noise signal and generating a combined output signal; a low-latency filter for processing a combined output signal and producing a final output signal, the processing circuit comprising: the time-frequency conversion module is used for respectively converting the ear canal microphone signal and the outside microphone signal in the time domain into an ear canal microphone frequency domain sub-band signal and an outside microphone frequency domain sub-band signal; An extraction combining module for predicting a predicted clean audio signal in each of the ear canal microphone frequency domain sub-band signal and the outside microphone frequency domain sub-band signal, and obtaining an effective audio signal excluding noise sources by combining a lower frequency band of the predicted clean audio signal from the ear canal microphone frequency domain sub-band signal and a higher frequency band of the predicted clean audio signal from the outside microphone frequency domain sub-band signal; A time domain synthesis module for converting the effective audio signal into an effective audio time domain signal through a subband synthesis process, the processing circuit further comprises a comparison module for comparing the effective audio time domain signal with the ear canal microphone signal to generate a noise feedback signal, the processing circuit further comprises an anti-noise signal module for combining the external microphone signal and the noise feedback signal to generate an anti-noise signal, the processing circuit further comprises a post-filtering module for reducing residual noise of the effective audio signal and outputting the residual noise to the time domain synthesis module, the processing circuit further comprises a transient noise reduction module for detecting transient noise from the ear canal microphone signal and outputting the reduced transient noise from the effective audio time domain signal to the comparison module, The extraction and combination module is further operable to update the weights of the linearly combined audio signals during the detected user speech, the extraction and combination module is further operable to calculate the weights of the linearly combined audio signals to model a relative transfer function of noise signal contributions between the ear canal microphone and the outside microphone, the analog-to-digital converter uses a multi-bit analog modulator for receiving the analog signal forwarded to the input pins of the integrated circuit, converting the analog signal into an encoded multi-bit digital signal, and then presenting it as a multi-bit digital output in an output, feeding back a single-bit digital modulator for converting the input multi-bit digital signal into a single-bit digital signal, The unit digital signal is in delta-sigma format, the unit digital signal being a serial stream of positive and negative pulses that are converted by multiples that increase in number of positive pulses as the amplitude of the modulated analog signal increases, the analog-to-digital converter comprising at least one decimator or at least one interpolator coupled to receive the multi-bit digital signal and to generate a multi-bit digital output signal that transitions at a frequency that is less than or greater than the transition frequency, respectively; The decimator may maintain delta-sigma format; a rate change switch associated with the decimator or interpolator may modify the frequency to maintain compatibility.
2. An earphone having the noise-reduction processed audio chip of claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110251243.2A CN112929780B (en) | 2021-03-08 | Audio chip and earphone of noise reduction processing |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110251243.2A CN112929780B (en) | 2021-03-08 | Audio chip and earphone of noise reduction processing |
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| CN112929780A CN112929780A (en) | 2021-06-08 |
| CN112929780B true CN112929780B (en) | 2024-07-02 |
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6326912B1 (en) * | 1999-09-24 | 2001-12-04 | Akm Semiconductor, Inc. | Analog-to-digital conversion using a multi-bit analog delta-sigma modulator combined with a one-bit digital delta-sigma modulator |
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6326912B1 (en) * | 1999-09-24 | 2001-12-04 | Akm Semiconductor, Inc. | Analog-to-digital conversion using a multi-bit analog delta-sigma modulator combined with a one-bit digital delta-sigma modulator |
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Address after: No. 2001, Yingbin West Road, Bacheng Town, Kunshan City, Suzhou City, Jiangsu Province, 215311 Applicant after: Kunshan Haifeiman Technology Group Co.,Ltd. Address before: 2 / F, North building, 1339 Shuixiu Road, Yushan Town, Kunshan City, Suzhou City, Jiangsu Province Applicant before: HEAD-DIRECT (KUNSHAN) Co.,Ltd. |
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Address after: 215300 No. 2001 Yingbin West Road, Bacheng Town, Kunshan City, Suzhou City, Jiangsu Province Applicant after: Kunshan Haifeiman Technology Group Co.,Ltd. Address before: No. 2001, Yingbin West Road, Bacheng Town, Kunshan City, Suzhou City, Jiangsu Province, 215311 Applicant before: Kunshan Haifeiman Technology Group Co.,Ltd. |
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Effective date of registration: 20240603 Address after: Room 202, No.1 Jintan Third Street, Shijie Town, Dongguan City, Guangdong Province, 523000 Applicant after: Dongguan Qibei Sonic Electronics Co.,Ltd. Country or region after: China Address before: 215300 No. 2001 Yingbin West Road, Bacheng Town, Kunshan City, Suzhou City, Jiangsu Province Applicant before: Kunshan Haifeiman Technology Group Co.,Ltd. Country or region before: China |
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