EURASIP Journal on Applied Signal Processing 
Volume 2003 (2003), Issue 7, Pages 668-675
doi:10.1155/S1110865703305013

Joint Acoustic and Modulation Frequency

Les Atlas1 and Shihab A. Shamma2

 1Department of Electrical Engineering, Box 352500, Seattle 98195-2500, WA, USA
2Department of Electrical and Computer Engineering and Center for Auditory and Acoustic Research, Institute for Systems Research, University of Maryland, College Park 20742, MD, USA
Received 30 August 2002; Revised 5 February 2003

Abstract

There is a considerable evidence that our perception of sound uses important features which is related to underlying signal modulations. This topic has been studied extensively via perceptual experiments, yet there are few, if any, well-developed signal processing methods which capitalize on or model these effects. We begin by summarizing evidence of the importance of modulation representations from psychophysical, physiological, and other sources. The concept of a two-dimensional joint acoustic and modulation frequency representation is proposed. A simple single sinusoidal amplitude modulator of a sinusoidal carrier is then used to illustrate properties of an unconstrained and ideal joint representation. Added constraints are required to remove or reduce undesired interference terms and to provide invertibility. It is then noted that the constraints would also apply to more general and complex cases of broader modulation and carriers. Applications in single-channel speaker separation and in audio coding are used to illustrate the applicability of this joint representation. Other applications in signal analysis and filtering are suggested.