Noncategorical identification of rise time

The view that speech and certain nonspeech signals such as music are perceived categorically has been contradicted by many studies. In most studies, subjects identified many different stimuli as belonging to one of two classes (e.g., “pluck” and “bow”). To determine whether subjects can identify exactly each of a number of different stimuli, subjects heard a sawtooth wave contained within six different amplitude envelopes. In one task, subjects learned the envelopes by rise-time value (10, 20, 30, 40, 50, and 60 msec), and later identified them by pressing labeled keys. Analysis of responses showed that accuracy of estimating envelope rise time is not worse than ± 10 msec. It is concluded that subjects trained in auditory perception do not classify a continuum of sawtooth waveforms varying in rise time into two sharply defined categories, but are able to resolve rise-time values with much greater accuracy than is achieved by simply dividing the 10–60 msec range into two categories such as “pluck” and “bow.”