This chapter provides an introduction to the physiology of hearing, covering the physics and analysis of sound, the structure and function of the outer and middle ears, the cochlea, the auditory nerve, and the mechanisms of transduction and excitation in the cochlea. It also discusses the brainstem nuclei, the auditory cortex, centrifugal pathways, and the physiological correlates of auditory psychophysics and performance. The chapter concludes with a section on sensorineural hearing loss, including types, physiological aspects, and cochlear prosthesis.This chapter provides an introduction to the physiology of hearing, covering the physics and analysis of sound, the structure and function of the outer and middle ears, the cochlea, the auditory nerve, and the mechanisms of transduction and excitation in the cochlea. It also discusses the brainstem nuclei, the auditory cortex, centrifugal pathways, and the physiological correlates of auditory psychophysics and performance. The chapter concludes with a section on sensorineural hearing loss, including types, physiological aspects, and cochlear prosthesis.