Identification of musical chords using CONSTANT-Q spectra

We present an approach to the extraction of frequencies corresponding to chords in western polyphonic music. In the first phase of this approach constant-Q spectral analysis directly provides the features from which the fundamental frequencies for 43 of the 57 possible categories of chords can be extracted without ambiguity. Each remaining chord category has a potential ambiguity associated with it because of frequency resolution problems. The second phase of our approach is designed to address such ambiguities. A software implementation of our approach was used successfully to validate its performance on a representative set of polyphonic musical signals.