Definicija: Sistem, katerega naloga je zaznavati zvok. Pri sesalcih na bazilarni membrani leži skupek celic, ki je ključen za naše dojemanje zvokov (Cortijev organ), pri nižjih vretenčarjih so to zaznavni receptorji na lageni (organ za sluh in ravnotežje). Pri človeku lahko ta organ zaznava zvok med 16 in 27.000 Hz, vendar je najbolj občutljiv za frekvenco med 2.000 Hz in 5.000 Hz. Zvok potuje preko koščic srednjega ušesa in polža do slušnega živca.

Definicija: The system that is concerned with the perception of sound, is mediated through the organ of Corti of the ear in mammals or through corresponding sensory receptors of the lagena in lower vertebrates, is normally sensitive in man to sound vibrations between 16 and 27.000 cycles per second but most receptive to those between 2.000 and 5.000 cycles per second, is conducted centrally by the cochlear branch of the auditory nerve, and is coordinated especially in the medial geniculate body.