Interactive computer based music systems
Thesis DisciplineElectrical Engineering
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
The application of digital computing techniques to music is considered herein, with particular emphasis on interactive systems. Three distinct topics are discussed: computer aids for musicians, sound synthesis, and pitch trajectory estimation. A comprehensive review of the literature pertaining to each topic is presented.
An interactive "Piano Typewriter" system which permits music played on an electronic organ to be recorded for subsequent playback, display and editing is described. Two notations are incorporated - MOD (a positional notation) and TRAD (a subset of conventional notation). Particular attention is paid to the transcription of keyboard performance information for TRAD display, and its subsequent editing. Examples which illustrate the present state of the system are presented.
A digital synthesiser which is implemented in dedicated hardware and which permits a wide range of sound timbres to be generated and performed interactively under computer control is described.
Techniques for pitch trajectory estimation are reviewed in detail, and are assessed with respect to their suitability for wide-band musical signals. Numerical transform techniques for evaluating correlations are also reviewed. A new pitch estimation algorithm which operates in the time-domain by recognising recurring "features" of the signal waveform is described and is related analytically to autocorrelation analysis. The performance of the new algorithm is compared with that of the Gold and Rabiner parallel processing algorithm, and it is concluded that the former is more suitable for most music and speech signals.