A new method for tracking modulations in tonal music in audio data format

Cq-profiles are 12-dimensional vectors, each component referring to a pitch class. They can be employed to represent keys. Cq-profiles are calculated with the constant Q filter bank. They have the following advantages: 1) they correspond to probe tone ratings; 2) calculation is possible in real-time; 3) stability is obtained with respect to sound quality; and 4) they are transposable. By using the cq-profile technique as a simple auditory model in combination with the SOM, an arrangement of keys emerges, that resembles results from psychological experiments and from the music theory. Cq-profiles are reliably applied to modulation tracking by introducing a special distance measure.