Physiological studies of directional hearing Free

This review concerns physiological studies of the neural mechanisms of sound localization. We will describe the responses of neurons in the central auditory system to sounds presented dichotically or in the free field. The free‐field studies have sought to define the spatial receptive fields of these neurons and their topographical organization in the brain. Although the functional aspects of these cells are most effectively addressed by free‐field methods, the mechanism by which these cells accomplish this task is best studied using dichotic stimulation. Influenced by the duplex theory and human psychoacoustics, the major focus of neurophysiological studies using dichotic stimulation has been the investigation of the effects of varying interaural phase and intensity. The neuronal responses to these stimuli and their relationship to the frequency domain will be discussed with a particular emphasis on the concept of characteristic delay. In an attempt to define the underlying circuitry, we will compare the neural responses to a model of a binaural cell. [This work supported by N.I.H. grants NS18027 (S. Kuwada), EY02606 (T. C. T. Yin), and NS12732 (J. E. Hind).]