Abstract:
A theory of the principal monaural pathway is described according to which temporal information is spatially coded on three dimensions roughly corresponding to the levels of, respectively, the cochlea, the inferior colliculus, and the auditory cortex [C. Schreiner and G. Langner, ``Coding of temporal patterns in the central auditory nervous system,'' Auditory Function: Neurobiological Bases of Hearing, edited by G. M. Edelman et al. (Wiley, New York, 1988), pp. 337--361]. This theory is expressed in the form of a computational model which simulates peripheral and central processing and which has the following main components: (1) a one-dimensional linear bandpass filter-bank to simulate the cochlea; (2) a two-dimensional amplitude-modulation (AM) bandpass filter-bank to simulate the colliculus; (3) a three-dimensional AM bandpass filter-bank to simulate layer IV receptive cells in the cortex; (4) a cortical cross-channel correlation mechanism; and (5) a central pattern recognition mechanism. Overall, periodicity pitch (i.e., periods of up to about 1000 Hz) is primarily associated with subcortical processing whereas time and rhythm (i.e., periods of up to about 20 Hz) are primarily associated with cortical processing. The model is applied to the following phenomena: virtual pitch shift, musical chords, the psychophysical law for interval discrimination, and the filled interval illusion.