On the dependence of ( f2−f1) difference tones on subject and on additional masker

Abstract

For a group of eight subjects showing stronger than usual irregularities in the level dependence of the quadratic distortion product, the level and phase of the (f2-f1) difference tone were measured using the method of cancellation for three sets of primary frequencies as a function of the primary levels. An additional masker seems to "linearize" the level dependence toward regular behavior. Using data sets produced with and without the additional masker, it is possible to separate two sources of quadratic nonlinearity, one with regular behavior presumably located in the middle ear and another with irregular behavior (similar to that of cubic distortion) presumably located in the characteristics of outer hair cells. Through the "subtraction" of empirically determined patterns from idealized patterns, it is possible to approximate patterns stemming from the inner-ear source alone.

Intermodulation components in inner hair cell and organ of Corti responses

“…However, when both components were examined for primaries at similar input levels, the two difference tones behaved in a similar fashion ͑Hall, 1972; Humes, 1985;Zwicker and Martner, 1990͒. Consequently, one should not rule out the possibility that they are produced by a single source which is consistent with the IHC results reported here.…”

Differences between psychoacoustic and frequency following response measures of distortion tone level and masking

“…Nonlinear processes in the inner ear, more specifically processes responsible for cochlear amplification, are thought to underlie the generation of the audible CDT and part of the QDT. For the QDT, there is probably an additional component generated in the middle ear (e.g., Hall, 1972; Zwicker and Martner, 1990). The cochlear mechanical origin of the DPs is assumed to be in the region where the primaries interact, close to the F 2 place (e.g.…”