Multidimensional Timbre Analysis of Melody

This presentation describes the timbre analysis technique designed by Bolger (2004) for the analysis of melodic music. The technique described uses the multidimensional model of timbre and is composed of two parts. The first part performs a time-frequency analysis of the input musical signal using the short-time-Fourier-transform (STFT) and takes account of the perceptual phenomena of frequency weighting (Fletcher-Munson equal loudness curves) and spectral masking before calculating the timbre descriptors. The application of these perceptually based processes serves to render the timbre calculations more perceptually relevant. Only brief overview of this first phase of the timbre analysis technique is presented as the focus of this presentation is on the second part. This second phase of the analysis procedure is concerned with the representation of timbre change over the time-course of the input melodic signal using the multidimensional timbre data generated in the first part of the analysis. This timbre change analysis is carried out using a self-organising-feature-map (SOFM) (Kohonen, 1989); an unsupervised neural network frequently employed in pattern recognition. Throughout the description of the timbre change analysis the various significant difficulties and issues associated with the analysis of multidimensional timbre in a melodic musical context are presented and explored. The application and contribution of existing techniques of musical timbre analysis (Tsang, 2002 and Malloch, 2004) and theories of timbre (Lerdahl, 1987) to the difficulties and issues encountered are explained. To conclude, an example of the implementation of this timbre analysis technique to a piece of Japanese shakuhachi music of the honkyoku tradition is presented.

References:

Bolger, D., 2004. Computational Models of Musical Timbre and the Analysis of its Structure in Melody, PhD. Thesis, University of Limerick.

Grey, J. M., 1975. "Exploration of Musical Timbre", Standford University Dept of Music Technical Report, STAN-M-2.

Grey, J. M., 1977. "Multidimensional Perceptual Scaling of Musical Timbre", Journal of the Acoustical Society of America, 64(2), pp467-471.

Gutzwiller, A. and G. Bennett, 1991. "The World of a Single Sound: Basic Structure of the Music of the Japanese Flute Shakuhachi", Musica Asiatica, 6, pp36-59.

Kohonen, T., 1989. Self Organisation and Associative Memory, Berlin, Springer-Verlag.

Lerdahl, F., 1987. "Timbral Hierarchies", Contemporary Music Review, vol. 2(1), pp135-160.

Malloch, S., 2004. "An exploration of timbre analysis: The game of sound in two performances of Jeux Vénitiens", Musicae Scientiae, vol.8(1), p53.

Tsang, L., 2002. "Towards a theory of timbre for music analysis", Musicae Scientiae, vol.6(1).