Verification of Simmons and Dixon's summation loudness decrement principle

Abstract

Loudness information is coded by the cochlea and the auditory nerve. This coding is explained on the basis of two operational mechanisms. The first is essentially a Place Principle, wherein the nerve fibers excited by outer hair cells require a less intense stimulus than do the. fibers excited by the inner hair cells (Harris, 1953). Traditionally, defects in the coding mechanism have been associated with Fowlers recruitment phenomenon (Simmons and Dixon, 1966). When the more sensitive outer hair cells (or related structures) are
damped, auditory threshold is elevated. However, when the undamaged inner hair cells are excited as a function of intensity raise, the resulting loudness sensation eventually equals that of the undamaged ear.