Demodulation Processes in Auditory Perception.
Final rept. 1 Dec 1988-31 May 1992,
OHIO STATE UNIV COLUMBUS
Pagination or Media Count:
This document reports the accomplishments of a project on the application of the Envelope-Weighted Average of Instantaneous Frequency EWAIF model to the processing of complex, time-varying sounds. We consider the task of human listeners to be one of recovering information imposed on the sound stream by a variety of sources. These include speech, music and other environmentally- important signals. Information is encoded in amplitude envelope and angle frequency or phase modulations of the sound stream carrier . The human listener must demodulate the stream to recover the information. EWAIF first demonstrated that these modulations interact and could provide discrimination cues even for steady-state signals such as those used in profile analysis or co- modulation masking. This project revised the EWAIF model into the IWAIF version Intensity envelope-squared weighting leads to greater computational efficiency via the FFT and to an intuitively appealing representation. The IWAIF calculation leads to the center-of-gravity of the spectrum. Tracking frequency modulations imposed on a narrow bandwidth carrier, then may be thought of as tracking the spectral center of gravity. Work continues on the extension of the IWAIF model to handle processing of signals with multiple modulation sources and to refining the short-term tracking abilities of the model.