Acoustic activity detection apparatus and method
First Claim
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1. An apparatus configured to distinguish speech activity from background noise, the apparatus comprising:
- an analog circuit that converts sound energy into an analog electrical signal;
a conversion circuit coupled to the analog circuit that converts the analog signal into a digital signal;
a digital circuit coupled to the conversion circuit, the digital circuit including an acoustic activity detection (AAD) module, the AAD module configured to receive the digital signal, the digital signal comprising a sequence of frames, each frame having a plurality of samples, the AAD module configured to obtain an energy estimate for the plurality of samples of a frame and compare the energy estimate to at least one threshold, and the AAD module configured to determine whether speech or noise is detected based on the comparison, and when speech is detected to trigger transmission of an interrupt;
wherein the conversion circuit comprises a sigma-delta modulator that is configured to convert the analog signal into a single bit stream pulse density modulated (PDM) format;
wherein the digital circuit comprises a decimator module that converts the single bit stream pulse density modulated (PDM) format into a pulse code modulated (PCM) format;
wherein the pulse code modulated (PCM) audio from the decimator module is stored in a buffer while the AAD module determines whether speech or noise is detected.
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Abstract
Streaming audio is received. The streaming audio includes a frame having plurality of samples. An energy estimate is obtained for the plurality of samples. The energy estimate is compared to at least one threshold. In addition, a band pass estimate of the signal is determined. An energy estimate is obtained for the band-passed plurality of samples. The two energy estimates are compared to at least one threshold each. Based upon the comparison operation, a determination is made as to whether speech is detected.
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Citations
22 Claims
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1. An apparatus configured to distinguish speech activity from background noise, the apparatus comprising:
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an analog circuit that converts sound energy into an analog electrical signal; a conversion circuit coupled to the analog circuit that converts the analog signal into a digital signal; a digital circuit coupled to the conversion circuit, the digital circuit including an acoustic activity detection (AAD) module, the AAD module configured to receive the digital signal, the digital signal comprising a sequence of frames, each frame having a plurality of samples, the AAD module configured to obtain an energy estimate for the plurality of samples of a frame and compare the energy estimate to at least one threshold, and the AAD module configured to determine whether speech or noise is detected based on the comparison, and when speech is detected to trigger transmission of an interrupt; wherein the conversion circuit comprises a sigma-delta modulator that is configured to convert the analog signal into a single bit stream pulse density modulated (PDM) format; wherein the digital circuit comprises a decimator module that converts the single bit stream pulse density modulated (PDM) format into a pulse code modulated (PCM) format; wherein the pulse code modulated (PCM) audio from the decimator module is stored in a buffer while the AAD module determines whether speech or noise is detected. - View Dependent Claims (2, 3)
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4. A microphone apparatus comprising:
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a sensor having an output with an electrical signal produced in response to acoustic energy detected by the sensor; a converter having an input coupled to the output of the sensor, the converter having an output with a digital signal obtained from the electrical signal; a buffer coupled to the output of the converter, data based on the digital signal buffered in the buffer; a voice activity detector coupled to the output of the converter, the voice activity detector distinguishing speech-like activity from non-speech based on a comparison of energy estimates of samples of data based on the digital signal to a threshold while the data is buffered, the threshold determined at least in part by noise statistics that are independent of noise type; an external-device interface coupled to the buffer, wherein a wake-up signal and data delayed by the buffer are provided to the external-device interface after the voice activity detector determines the presence of speech-like activity in the frame. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method in a microphone apparatus having an acoustic sensor, a converter, a buffer, a voice activity detector, and an external-device interface, the method comprising:
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generating an electrical signal in response to an acoustic input at the sensor; converting the electrical signal to a digital signal using the converter; distinguishing speech-like activity from non-speech by comparing an energy estimate for samples of data based on the digital signal to a threshold using the voice activity detector, the threshold determined at least in part by noise statistics that are independent of noise type; buffering data based on the digital signal in the buffer while distinguishing speech-like activity from non-speech; and providing a wake-up signal and data delayed by the buffer to the external-device interface after determining the presence of speech-like activity. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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Specification