This dissertation introduces a new analysis/synthesis method. It is designed to obtain
musically useful intermediate representations for sound transformations. The method’s
underlying model assumes that a sound is composed of a deterministic component plus a
stochastic one. The deterministic component is represented by a series of sinusoids that are
described by amplitude and frequency functions. The stochastic component is represented
by a series of magnitude-spectrum envelopes that function ...
This dissertation introduces a new analysis/synthesis method. It is designed to obtain
musically useful intermediate representations for sound transformations. The method’s
underlying model assumes that a sound is composed of a deterministic component plus a
stochastic one. The deterministic component is represented by a series of sinusoids that are
described by amplitude and frequency functions. The stochastic component is represented
by a series of magnitude-spectrum envelopes that function as a time-varying filter excited
by white noise. Together these representations make it possible for a synthesized sound
to attain all the perceptual characteristics of the original sound. At the same time the
representation is easily modified to create a wide variety of new sounds.
This analysis/synthesis technique is based on the short-time Fourier transform (STFT).
From the set of spectra returned by the STFT, the relevant peaks of each spectrum are
detected and used as breakpoints in a set of frequency trajectories. The deterministic signal
is obtained by synthesizing a sinusoid from each trajectory. Then, in order to obtain the
stochastic component, a set of spectra of the deterministic component is computed, and
these spectra are subtracted from the spectra of the original sound. The resulting spectral
residuals are approximated by a series of envelopes, from which the stochastic signal is
generated by performing an inverse-STFT.
The result is a method that is appropriate for the manipulation of sounds. The intermediate
representation is very flexible and musically useful in that it offers unlimited
possibilities for transformation.
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