Subject: Re: Detection of harmonics and rhythmic structure From: Neil Todd <TODD(at)FS4.PSY.MAN.AC.UK> Date: Fri, 12 May 2000 12:05:42 GMT
Dear Brian and List An algorithm that has some physiological and psychophysical plausibility is to compute the modulation power spectrum (see refs below). (a) harmonic structure For the extraction of harmonic structure the most recent version of this has the following components (i) outer-middle ear, standard table (ii) gammatone filter bank (iii) hair-cell (iv) low-pass 40 Hz (v) onset-cells (vi) modulation band-pass filter bank, approx. 0.5 - 16 Hz (b) beat induction If you wish to extract a beat you also need a preferred tempo mechanism, which we have argued can only be accounted for by the addition a motor component, since a sense of beat has a quite narrow existence region, much narrower that our range of temporal discriminability. This shouldn't be controversial if you consider that most music that has a beat is dance music. (c) rhythmic structure Note that rhythmic structure can exist is the absense of a clear beat or harmonic structure. Rhythm involves the interaction of both temporal grouping and metre. We have argued that temporal grouping can be extracted by a modulation low-pass filter system. Thus a complete description of rhythm requires both the band-pass and low-pass represenations and a motor representation. Cheers Neil Todd Todd, N.P.McAngus (1994) The auditory primal sketch: A multi-scale model of rhythmic grouping. J. New Music Research 23(1), 25-70. Todd, N.P.McAngus (1995) The kinematics of musical expression. J. Acoust. Soc. Am. 97(3), 1940-1949. Todd, N.P.McAngus (1996) An auditory cortical theory of auditory stream segregation. Network : Computation in Neural Systems. 7, 349-356. Todd, N.P.McAngus and Brown, G.J. (1996) Visualization of rhythm, time and metre. Artificial Intelligence Review 10, 253-273. Todd, N.P.McAngus, Lee, C.S. and O'Boyle, D.J. (1999) A sensory-motor theory of rhythm, time perception and beat induction. J. New Music Research. 28(1), 5-29. Todd, N.P.McAngus (1999) Motion in Music: A neurobiological perspective. Music Perception. 17(1), 115-126. Todd, N.P.McAngus et al (2000) A sensory-motor theory of beat induction. Human vs. Machine Performance. Proceedings of the Sixth International Conference on Music Perception and Cognition. Keele.