Auditory psychophysics: spectrotemporal representation of signals

The study of audition has widened: Having been concentrated in the 1960s on a few topics like pitch perception, binaural hearing, and fatigue, it now spans many more subjects. In the present paper we have emphasized the following topics: frequency analysis--this topic includes spectral integration and resolution, auditory excitation patterns, and processing of spectral information; temporal analysis--this topic refers mainly to studies in which abstract and stylized temporal variations in stimuli are used; binaural hearing--a subfield that still attracts a great deal of attention because of its unique character; pitch perception--of particular interest is this field for the perception of prosodic features of speech, but it also addresses fundamental questions of how the auditory system works; and pathology of hearing--in particular the effects of impaired hearing on speech perception and the relations among various hearing-test results. (This section was written in collaboration with W. A. Dreschler.) Many of the topics discussed have a direct relation to the capabilities of the auditory system in analyzing sounds--in particular, speech sounds. Experimentally, the problem can be approached from two sides: in one the stimuli are generated in a stylized form, and in the other they are taken as distorted versions of actual speech elements. In this paper we have described mainly the first category of experiments. Whereas we know for certain that the auditory system operates in the frequency-temporal domain, it is remarkable that the distinction between fields 1 and 2 (above) can still be made. Temporal effects in frequency analysis are often considered as perturbations, and the same is true for spectral effects in the study of temporal resolution. A true integration of time and frequency is often sought but seldom achieved as the focus of study. Of the many subjects that would ideally have received more coverage we mention two: the use of additional stimulation pathways to help patients with large hearing loss or deaf-blind people, and the use of a cochlear prosthesis ("cochlear implant"). Because we lacked space to cover these topics adequately, we omitted them completely. This indicates no undervaluation of these subjects of study or of the benefits they can provide to hearing-impaired people.