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US 9,002,030 B2Granted
System and method for performing voice activity detection
AssigneeAudyssey Laboratories, Inc.
InventorsSunil Bharitkar, Nathan Dahlin
Life of this patent
Estimating the term…
Abstract
A Voice Activity Detection (VAD) algorithm provides a simple binary signal indicating the presence or absence of speech in a microphone signal. The VAD algorithm includes a first step of noise suppression which both estimates and removes (i.e., filters) ambient noise from the microphone signal to create a filtered signal. The magnitude of the filtered signal is then compared to a threshold in order to produce a VAD output signal. The threshold is dynamic and may be derived either from the filtered signal itself, or from a noise spectrum estimate calculated by the noise suppression step.
Claims9
A method for Voice Activity Detection (VAD), the method comprising the steps of:
- producing a microphone signal including speech and ambient noise by a microphone;
- providing the microphone signal to noise suppression processing;
- processing the microphone signal in the noise suppression processing to generate an ambient noise estimate, comprising:
- buffering and windowing the microphone signal to create time domain frames;
- transforming the time domain frames into frequency domain frame;
- and
- computing noise estimates of each of the frequency domain frames;
- providing the ambient noise estimate to threshold calculation;
- calculating a threshold as the square root and mean of the noise estimates;
- provided the threshold to the VAD logic;
- computing a noise suppressed signal from the microphone signal and the ambient noise estimate by the noise suppression processing, comprising:
- computing trim values from the noise estimates;
- and
- scaling the frequency domain frame by the trim values;
- comparing the noise suppressed signal to the threshold in the VAD logic;
- setting a VAD signal to 0 when the noise suppressed signal is below the threshold;
- and
- setting a VAD signal to 1 when the noise suppressed signal is above the threshold.
15 more elements
A method for Voice Activity Detection (VAD), the method comprising the steps of:
- producing a microphone signal including speech and ambient noise by a microphone;
- providing the microphone signal to noise suppression processing;
- processing the microphone signal in the noise suppression processing to generate an ambient noise estimate, comprising:
- buffering and windowing the microphone signal to create time domain frames:
- sequentially transforming the time domain frames into microphone signal frequency domain frames;
- and
- computing frequency domain noise estimate frames of each of the microphone signal frequency domain frames;
- providing the ambient noise estimate to threshold calculation;
- calculating a threshold;
- provided the threshold to the VAD logic;
- computing a noise suppressed signal from the microphone signal and the ambient noise estimate by the noise suppression processing, comprising:
- calculating trims from the frequency domain noise estimate frames;
- and
- scaling the microphone signal frequency domain frames using the trims to obtain the noise suppressed signal;
- calculating a signal energy estimate as the square of the magnitude of the noise suppressed signal;
- comparing the signal energy estimate to a threshold in the VAD logic;
- setting a VAD signal to 0 when the signal energy estimate is below the threshold;
- setting a VAD signal to 1 when the signal energy estimate is above the threshold.
15 more elements
A method for Voice Activity Detection (VAD), the method comprising the steps of:
- producing a microphone signal including speech and ambient noise by a microphone;
- buffering and windowing the microphone signal to create time domain frames;
- sequentially transforming the time domain frames into microphone signal frequency domain frames;
- computing frequency domain ambient noise estimate frames of each of the microphone signal frequency domain frames;
- providing the frequency domain ambient noise estimate to threshold calculation;
- calculating a threshold by taking the square root of each bin of the frequency domain noise estimate frames and then taking the mean of the square roots of each bins;
- provided the threshold to the VAD logic;
- calculating trims from the frequency domain noise estimate frames;
- scaling the microphone signal frequency domain frames using the trims to obtain a frequency domain noise suppressed signal;
- inverse transforming the frequency domain noise suppressed signal into a time domain noise suppressed signal;
- buffering and windowing the time domain noise suppressed signal;
- provided the buffered and windowed time domain noise suppressed signal to the VAD logic;
- comparing the buffered and windowed time domain noise suppressed signal to a threshold in the VAD logic;
- setting a VAD signal to 0 when the windowed time domain noise suppressed signal is below the threshold;
- and
- setting a VAD signal to 1 when the windowed time domain noise suppressed signal is above the threshold.
13 more elements
A method for Voice Activity Detection (VAD), the method comprising the steps of:
- producing a microphone signal including speech and ambient noise by a microphone;
- buffering and windowing the microphone signal to create time domain frames;
- sequentially transforming the time domain frames into microphone signal frequency domain frames;
- computing frequency domain noise estimate frames of each of the microphone signal frequency domain frames;
- calculating trims from the frequency domain noise estimate frames;
- scaling the microphone signal frequency domain frames using the trims to obtain a frequency domain noise suppressed signal;
- inverse transforming the frequency domain noise suppressed signal into a time domain noise suppressed signal;
- buffering and windowing the time domain noise suppressed signal;
- squaring the buffered and windowed time domain noise suppressed signal to generate a signal energy estimate;
- determining a threshold using prior signal energy estimate;
- comparing the present signal energy estimate to the threshold in the VAD logic;
- setting a VAD signal to 0 when the signal energy estimate is below the threshold;
- and
- setting a VAD signal to 1 when the signal energy estimate is above the threshold.
11 more elements
Dependencies are inferred from the claim text.