1. A method of operation in a speech recognition system, the method comprising: analyzing each of a plurality of frames of audio by a sound classifier; classifying a first number of the frames of audio as speech by the sound classifier; classifying a second number of the frames of audio as non-transient background noise by the sound classifier; classifying a third number of the frames of audio as transient noise events by the sound classifier; and providing signals indicative at least of the classifications of the frames of audio to a speech recognizer.