1997 Articles

The weft: A representation for periodic sounds

Ellis, Daniel P. W.

For the problem of separating sound mixtures, periodicity is a powerful cue used by both human listeners and automatic systems. Short-term autocorrelation of subband envelopes, as in the correlogram, accounts for much perceptual data. We present a discrete representation of common-period sounds, derived from the correlogram, for use in computational auditory scene analysis: The weft describes a sound in terms of a time-varying periodicity and a smoothed spectral envelope of the energy exhibiting that period. Wefts improve on several aspects of previous approaches by providing, without additional grouping, a single, invertible element for each detected signal, and also a provisional solution to detecting and dissociating energy of different periodicities in a single frequency channel (unlike systems which allocate whole frequency channels to one source). We define the weft, describe the analysis procedure we have devised, and illustrate its capacity to separate periodic sounds from other signals.