Derivation of a Synthesis Model from Time-Variant Spectral Analysis

An effective spectrum‐based musical instrument synthesis model requires that time‐variant spectrum analysis (TVSA) be performed on a large group of tones representing the entire pitch and dynamic range of the instrument. Once enough common properties in the TVSA results are identified, a synthesis model can be devised, implemented, and tested. When the synthesis model is sufficiently complete, it can be employed in music performance or timbral research. It is important that a synthesis model’s physical parameters strongly correlate with perceived timbral features. Our current model employs three time‐variant parameters: rms amplitude, spectral centroid, and fundamental frequency, which strongly correlate with loudness, brightness, and pitch. In addition, a centroid‐controlled transfer function, preconstructed by averaging TVSA data from the original set of analyzed tones, is used to generate the detailed time‐variant spectra. When the three time‐variant parameters are matched to those measured in particular instrument tones, global contours and micro‐details emerge that contribute to synthesis realism. Small perceptual differences between original and synthetic sounds, which some listeners perceive as ‘‘roughness,’’ may be caused by smoothing of asynchronous spectral fluctuations in the synthesis. Current research is attempting to data‐reduce both the time‐variant control parameters and the centroid‐controlled transfer function without sacrificing quality