Abstract:

During the past decade, psychophysical research on the processing of amplitude modulation (AM) has expanded to relatively complex situations where subjects are asked to make detection or discrimination judgments regarding some aspect of AM in the presence of competing AM. This AM-masking paradigm has been referred to as modulation masking when the signal and masker carriers are overlapping noise bands, and as modulation detection (or discrimination) interference (MDI) when the two carriers are sinusoids. An important finding in the MDI paradigm is that this AM masking occurs even when the sinusoidal carriers are 2 or more oct apart, and hence under conditions where peripheral interactions within a single auditory filter are unlikely. It also occurs when the signal and masker carriers are presented to opposite ears, further evidence that at least some of the AM masking is occurring at a relatively central site in the auditory system. Finally, a common finding in these masking experiments is a rather broad tuning for the detection (or discrimination) of AM. Whether this turning should be taken as evidence for AM channels in the auditory system will be discussed, as will recent research on subjects with cochlear hearing loss. [Work supported by NIDCD.]