Book on

DAFX - Digital Audio Effects

Edited by Udo Zölzer
ISBN: 0-471-49078-4
John Wiley & Sons, 2002

Chapter 8

Time-frequency Processing

Matlab for Chapter 8

D. Arfib, F. Keiler and U. Zölzer

This chapter describes the use of time-frequency representations of signals in order to produce transformations of sounds. A very interesting (and intuitive) way of modifying a sound is to make a two-dimensional representation of it, modify this representation in some or other way and reconstruct a new signal from this representation. Consequently a digital audio effect based on time-frequency representations requires three steps: an analysis (sound to representation), a transformation (of the representation) and a resynthesis (getting back to a sound). We introduce the fundamental techniques for time-frequency processing, demonstrate several implementation schemes and illustrate the variety of effects possible in the two-dimensional time-frequency domain.


Keywords: Time-frequency Processing, Signal Representations, Transforms, Fourier Transforms, Phase Vocoder