Cochlear gain control tracks intensity changes only up to about 1 kHz

Evidence

The mechanical nonlinearity of the mammalian cochlea is clearly fast, but not instantaneous. The results of the current investigation show that dynamic changes in stimulus intensity can only be followed accurately up to a rate of ~ 1 kHz in the basal turn of the gerbil cochlea. This limitation appears to be produced by a low-pass gain control filter of some kind: this could be a mechanical filter, imparted by the load on a force generating element (such as a motile outer hair cell, or OHC), or an electrical filter (such as the OHC’s basolateral membrane, cf. Housley and Ashmore 1992 ). — Dijk, Pim van, Physiology, Psychoacoustics and…, 3657

The mechanical nonlinearity of the mammalian cochlea is clearly fast, but not instantaneous. The results of the current investigation show that dynamic changes in stimulus intensity can only be followed accurately up to a rate of ~ 1 kHz in the basal turn of the gerbil cochlea. This limitation appears to be produced by a low-pass gain control filter of some kind: this could be a mechanical filter, imparted by the load on a force generating element (such as a motile outer hair cell, or OHC), or an electrical filter (such as the OHC’s basolateral membrane, cf. Housley and Ashmore 1992 ). The filter could even involve a combination of multiple, coupled mechanisms: preliminary analysis suggests that the gain at one site on the BM may be controlled remotely, presumably by elements (e.g., OHCs) that are distributed more basally along the BM. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3657

Categorization

• QUESTION: What is the precise upper frequency for cochlear gain control in humans vs gerbils, and what are the psychophysical correlates of this ~1kHz limit?
• XREF: Connects to the reader’s existing interest in how fast the inner-hair-cell / OHC electromotility cascade can actually respond — relevant to whether timing precision limits in normal hearing are mechanical in origin. — connects to: Cochlear compression operates via a gain control with finite attack and release times. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3625; The cochlea cannot track dynamic intensity changes above roughly 1 kHz; The cochlea may regulate gain slowly rather than compress sound instantly — Dijk, Pim van, Physiology, Psychoacoustics and…, 3628 (+1 more)
• corroborated: 3 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 3657

Broader Connections

• The cochlea cannot track dynamic intensity changes above roughly 1 kHz #corroborates (0.90)
• The cochlea may regulate gain slowly rather than compress sound instantly #expands (0.78) — Dijk, Pim van, Physiology, Psychoacoustics and…, 3628
• Brain efferents can dynamically adjust cochlear gain during listening #complicates (0.75)