Patent ID: 6453285
Filing Date: 2002-09-17
Classification: G10L

Abstract:
A speech activity detector for detecting whether speech signals are present in individual time frames of an input signal, the speech activity detector comprising:a speech detector that receives as input the input signal and examines the input signal in order to generate a plurality of statistics that represent characteristics indicative of the presence or absence of speech in a time frame of the input signal, and generates an output based on the plurality of statistics representing a likelihood of speech presence in a current time frame, the plurality of statistics further comprising: a speech energy change statistic representing a change in energy within speech frequency bands between a first group of one or more time frames and a second group of one or more time frames; and a spectral deviation change statistic representing a change in the spectral shape of speech frequency bands of the input signal between a first group of one or more time frames and a second group of one or more time frames; and a state machine coupled to the speech detector and having a plurality of states, the state machine receiving as input the output of the speech detector and transitioning between the plurality of states based on a state at a previous time frame and the output of the speech detector for the current time frame, the state machine generating as output a speech activity status signal based on the state of the state machine which provides a measure of the likelihood of speech being present during the current time frame, the plurality of states comprising: a reset state representing identification of a change in background noise level; and one or more speech present states, wherein each of the one or more speech present states has an associated likelihood of speech being present during the current time frame.