a method for identifying end of voiced speech within an audio stream of a noisy environment employs a speech discriminator . the discriminator analyzes each window of the audio stream , producing an output corresponding to the window . the output is used to classify the window in one of several classes , for example , speech , silence , or noise . a state machine processes the window classifications , incrementing counters as each window is classified : speech counter for speech windows , silence counter for silence , and noise counter for noise . if the speech counter indicates a predefined number of windows , the state machine clears all counters . otherwise , the state machine appropriately weights the values in the silence and noise counters , adds the weighted values , and compares the sum to a limit imposed on the number of non - voice windows . when the non - voice limit is reached , the state machine terminates processing of the audio stream .