ABSTRACT
This chapter explores the general form of the envelope-detector model and the derivation of the model parameters. It discusses modulation detection thresholds (MDTs) for normal and hearing-impaired listeners are compared with MDTs simulated by a single-channel envelope-detector model incorporating traditional peripheral filter bandwidths, half-wave rectification, a low-pass filter stage, and a max/min decision statistic. The model successfully simulates normal modulation detection and many qualitative trends shown by hearing-impaired listeners. In 1979, Viemeister reported the measurement of a temporal modulation transfer functions (TMTFs) to describe how human observers detect amplitude modulation (AM) of a broadband noise signal as a function of AM frequency. Perhaps the chief advantage of simulating TMTF results for hearing-impaired listeners with an envelope-detector scheme is that the variable components of the three-stage model functionally represent the mechanical, sensory, and neural levels of the auditory pathway.
