Method and apparatus for voice activity detection

A method for voice activity detection, comprising:

• filtering an audio input signal on a frame-by-frame basis through a gammatone filterbank, operating in the frequency domain, to generate gammatone filtered output signals over a plurality of frequency channels;
• generating a plurality of energy envelopes from the gammatone filtered output signals, each energy envelope being calculated for each audio frame;
• constructing a plurality of weighting factors for each of the plurality of energy envelopes;
• applying each of the plurality of weighting factors, via a plurality of respective multipliers, to each of the plurality of energy envelopes, thereby generating a plurality of normalized weighted signals;
• measuring entropy across frequency for the plurality of normalized weighted signals over a predetermined time window to generate an entropy signal;
• averaging the entropy signal over the predetermined time window;
• computing an adaptive threshold;
• comparing the averaged entropy signal to the adaptive threshold;
• and
• applying decision logic to the comparison to indicate speech activity and indicate noise activity.

A communication device, comprising:

• a controller providing an audio processing stage for detecting voice activity and determining, based on the voice activity, that the audio signal is a voice command through a voice activity detection apparatus, comprising:
• a gammatone filterbank, operating in a frequency domain, for filtering audio frame inputs into filtered gammatone output signals;
• and
• a signal energy calculator performing energy signal calculations on the filtered gammatone output signals to generate a plurality of energy envelopes, each energy envelope being calculated for each audio frame;
• a plurality of multipliers for applying a respective weighting factor to each of the plurality of energy envelopes thereby producing a normalized weighted signal, in which voice regions are emphasized and noise regions are minimized, for each audio frame;
• an entropy measurement stage for measuring and extracting information from the normalized weighted signals;
• an adaptive entropy threshold for comparing the extracted information to a noise floor;
• and
• decision logic for identifying speech and noise from the comparison.