1. A method of identifying, among a plurality of audio files, a first one of the audio files, the method employing a segment of audio data which is derived from the first audio file and comprising the steps of: (a) creating an observation vector with audio features extracted from the segment of audio data; and (b) recognizing the first audio file using the observation vector; wherein the audio features comprise features obtained by analyzing the audio data, or a transformed version of the audio data, to derive a transform based on its significant features, and applying the transform to the audio data, or the transformed version of the audio data respectively, to obtain amplitudes of the significant features.