Auditory Physiology Overview

Principles

Definition

Auditory physiology is the academic discipline concerned with the biological mechanisms underlying auditory perception. It investigates the structural and functional properties of the auditory system, spanning from the peripheral sensory organs to the central neural pathways and cortical processing, to elucidate how sound is detected, transduced, transmitted, and interpreted by organisms.

Ontological type

Central auditory pathways

Peripheral mechanisms

Clinical implications

Key developments

Key Figures

Peripheral-Central Integration era

Steven A. Hillyard [1], associated with University of California, San Diego [3] and University of California, Los Angeles [4] during this era, helped bridge peripheral mechanics with central neural coding by focusing on how brain signals reflect attentional modulation of sensory input. His key contribution includes identifying electrical signs of selective attention in the human brain through the paper Electrical Signs of Selective Attention in the Human Brain [6], which shed light on how attention shapes neural processing in the auditory and broader sensory systems and thus connected cochlear mechanics to cortical representations in this era. Terence W. Picton [2], associated with University of California, San Diego [3] and University of Toronto [5] during this era, contributed to the same program by investigating auditory-evoked potentials and attention-related neural activity in the central nervous system. Picton's work helped define the era's emphasis on how temporal patterns and firing rates reflect frequency and intensity, as illustrated by the Electrical Signs of Selective Attention in the Human Brain [6], underscoring the central integration of peripheral input and cortical processing.

Active Mechanics and Neural Mapping era

Steven A. Hillyard [1] was a leading figure in auditory neuroscience during the Active Mechanics and Neural Mapping era, with affiliations at Harvard University [3] and the University of California, San Diego [4]. His key contributions include identifying long-latency auditory evoked waves described in Two varieties of long-latency positive waves evoked by unpredictable auditory stimuli in man (1975) [7], demonstrating modulation of early sensory processing in the auditory cortex during auditory selective attention in Modulation of early sensory processing in human auditory cortex during auditory selective attention (1993) [8], and detailing the role of selective attention in the auditory vertex potential in Selective attention and the auditory vertex potential I. Effects of stimulus delivery rate (1976) [9], together laying the groundwork for noninvasive cognitive-auditory mapping in this era. William E. Brownell [2] contributed to the era from major centers such as Johns Hopkins University [5] and Baylor College of Medicine [6]. His 1985 work Evoked Mechanical Responses of Isolated Cochlear Outer Hair Cells [10] demonstrated the evoked mechanical responses of outer hair cells, providing crucial evidence for hair cell electromotility and the cochlear amplifier within the era's active-mechanics framework.

Activity-Dependent Plasticity era

M. Charles Liberman [1], affiliated with the Harvard–MIT Division of Health Sciences and Technology [3] and Harvard University [4], is a central figure in the Activity-Dependent Plasticity era. His key contributions include showing age-related cochlear synaptopathy and noise-induced cochlear neuropathy as early drivers of auditory decline, as documented in Age-Related Cochlear Synaptopathy: An Early-Onset Contributor to Auditory Functional Decline [7], Noise-induced cochlear neuropathy is selective for fibers with low spontaneous rates [8], and Primary Neural Degeneration in the Guinea Pig Cochlea After Reversible Noise-Induced Threshold Shift [9], underscoring that peripheral synaptopathy can occur with minimal threshold shifts and reshape central coding—central to this era's activity-driven perspective. Nina Kraus [2], with major appointments at University of California, San Francisco [5] and Northwestern University [6], has shaped the era by linking auditory neuroscience to musical experience and multisensory processing. Her work on experience-dependent plasticity is reflected in Musicians have enhanced subcortical auditory and audiovisual processing of speech and music [10], Musical Experience and the Aging Auditory System [11], and Training to Improve Hearing Speech in Noise: Biological Mechanisms [12], illustrating how musical training modulates subcortical function and aging-related changes to support hearing in noise.