The resolution of brief interaural time-difference changes: recordings from primary auditory cortical projection...

The ability of the auditory organ to resolve brief changes in an acoustic signal presented either monaurally or binaurally is not only of great importance in the processing of speech, it is also involved in the localization of sound stimuli and in selective listening. In the latter context, the electric activity of the primary auditory cortical projection field AI of the cat has been studied with the aim of evaluating specific response patterns evoked by brief changes in interaural time difference. The differences in response of the neuron populations sampled by two recording electrodes indicate that, within this area, there are significant differences in temporal resolution ability. Whereas click stimuli elicit distinct potential patterns at the two sites, with a brief change in interaural time difference, a marked response is recorded by only one of the electrodes. This response is characterized by a decrease in amplitude as the interaural time difference is reduced and as the duration of the time-shift stimulus decreases.