Physiology of Binaural Hearing

Abstract

The literature contains extensive anatomical, physiological, and behavioral evidence that the two ears work together. The central auditory nervous system receives signals from two external sources, the left and right ears, and then, based upon the nature of the stimulation to each ear, neural signals are relayed and, in some cases modified, and distributed over multiple, complex connections to higher centers in the brain. The descending, or efferent, pathways also influence encoding of information. As Brugge (1992) summarizes, "sound perception involves . . . sensory coding, temporal and spatial transformation, divergent and convergent projections, parallel and serial processing, localization of function and neuronal plasticity" (p. 1). Thus, the nature of the stimulation to each ear results in cascading effects throughout the central auditory system. The following discussion provides an overview of central auditory pathway structure and function of the binaural auditory system. The interested reader is referred to excellent current discussions of the neuroanatomy and neurophysiology of the central auditory pathways by Webster (1992, 1995), Warr (1992), Brugge (1992), and Irvine (1992). NEURAL RESPONSES