Combination tone: Absent but audible component

Abstract

When two or more tones are presented simultaneously, a listener can sometimes hear other tones that are not present. These other tones called ‘combination tones’ are thought to be induced by nonlinear activities in the inner ear. It is difficult to demonstrate this phenomenon because a listener cannot easily distinguish combination tones from primary tones. This paper introduces a unique method called the ‘sweep tone method’ by which combination tones can be perceptually distinguished from primary tones relatively easily. The importance of the non-linear characteristics of the intact auditory system is described.