An audio file is divided into frames in the time domain and each frame is compressed (6301) , according to a psycho-acoustic algorithm, into file in the frequency domain. Each frame is divided into sub-bands and each sub-band is further divided into split sub-bands (6306) . The spectral energy over each split sub-band is averaged for all frames (6307, 6310) . The resulting quantity for each split sub-band provides a parameter. The set of parameters can be compared to a corresponding set of parameters generated from a different audio file to determine whether the audio files are similar. In order to provide for the higher sensitivity of the auditory response, the comparison of individual split sub-bands of the lower order sub-bands can be performed. Selected constants can be used in the comparison process to improve further the sensitivity of the comparison. In the side-information generated by the psycho-acoustic compression, data related to the rhythm, i.e., related percussive effects, is present. The data known as attack flags can also be used as part of the audio frame comparison.
Apparatus & method for automatic classification/identification of similar compressed audio files