Spectral Envelopes in Sound Analysis and Synthesis
Diemo Schwarz · 1998
In this project, Spectral Envelopes in Sound Analysis and Synthesis, various methods for estimation, representation, le storage, manipulation, and application of spectral envelopes to sound synthesis were evaluated, improved, and implemented. A prototyping and testing environment was developed, and a function library to handle spectral envelopes was designed and implemented. For the estimation of spectral envelopes, after de ning the requirements, the methods LPC, cepstrum, and discrete cepstrum were examined, and also improvements of the discrete cepstrum method (regularization, stochastic (or probabilistic) smoothing, logarithmic frequency scaling, and adding control points). An evaluation with a large corpus of sound data showed the feasibility of discrete cepstrum spectral envelope estimation. After defining the requirements for the representation of spectral envelopes, filter coefficients, spectral representation, break-point functions, splines, formant representation, and high resolution matching pursuit were examined. A combined spectral representation with indication of the regions of formants (called fuzzy formants) was defined to allow for integration of spectral envelopes with precise formant descriptions. For le storage, new data types were defined for the SDIF Sound