A method of enhancing the audio quality in a reproduction medium having unknown
characteristics. With this method a predetermined finite set of single frequency
tones are generated and these tones are then passed through the reproduction medium
to generate an output signal, which in turn is passed through a set of sub-band
filters. Each of the sub-band filters pass at least a frequency corresponding to
one of the tones in the set of tones. The characteristics of the reproduction medium
is then estimated as a result of passing the output signal through the set of sub-band
filters. Based on the estimated characteristics of the reproduction medium, a set
of sub-band inverse filters are constructed. Finally before passing the audio signal
through the reproduction medium the signal is passed through the set of inverse
filters to improve the quality of the audio signal after it passes through the
reproduction medium.