US 5,686,683 A · Inverse transform narrow band/broad band sound synthesis

Abstract

An additive sound synthesis process for generating complex, realistic sounds is realized in a computationally efficient manner. In accordance with one aspect of the invention, polyphony is efficiently achieved by dosing the energy of a given partial between separate transform sums corresponding to different channels. In accordance with another aspect of the invention, noise is injected by randomly perturbing the phase of the sound, either on a per-partial basis or on a transform-sum basis. In the latter instance, the phase is perturbed in different regions of the spectrum to a degree determined by the amount of energy present in the respective regions of the spectrum. In accordance with yet another aspect of the invention, a transform sum representing a sound is processed in the transform domain to achieve with great economy effects achievable only at much greater expense outside the transform domain. Other transforms besides the Fourier transform may be used to advantage. For example, use of the Hartley transform produces comparable results but allows transforms to be computed at approximately twice the speed as the Fourier transform.

Claims14

Dependent claims

A method of producing a time-sampled representation of a sound having both narrowband components and broadband noise components, comprising the steps of:

specifying said sound at each of a plurality of successive instants as a sum of a plurality of sound partials, each defined parametrically in terms of a plurality of parameters;
for each of said sound partials:
selecting values from a transformed function, based on at least one of said parameters;
generating a random number;
scaling said random number, based on at least one of said parameters, to produce a scaled random number;
using said scaled random number to vary at least one of said parameters to produce a varied parameter;
scaling said values selected from said transformed function, based on at least said varied parameter, to produce scaled values;
and
adding said scaled values to an array of values representing said sound;
applying an inverse discrete mathematical transform to said array of values to produce a time-sampled representation of said sound over a time interval;
and
blending time-sampled representations of said sound over adjacent time intervals to produce said time-sampled representation of said sound.

9 more elements

Dependencies are inferred from the claim text.

Inverse transform narrow band/broad band sound synthesis

Life of this patent

Inverse transform narrow band/broad band sound synthesis

Life of this patent

Abstract

Claims14