Power Amplification in the Mammalian Cochlea

Research output: Contribution to journalArticle

Abstract

It was first suggested by Gold in 1948 [1] that the exquisite sensitivity and frequency selectivity of the mammalian cochlea is due to an active process referred to as the cochlear amplifier. It is thought that this process works by pumping energy to augment the otherwise damped sound-induced vibrations of the basilar membrane [2-4], a mechanism known as negative damping. The existence of the cochlear amplifier has been inferred from comparing responses of sensitive and compromised cochleae [5] and observations of acoustic emissions [6, 7] and through mathematical modeling [8, 9]. However, power amplification has yet to be demonstrated directly. Here, we prove that energy is indeed produced in the cochlea on a cycle-by-cycle basis. By using laser interferometry [10], we show that the nonlinear component of basilar-membrane responses to sound stimulation leads the forces acting on the membrane. This is possible only in active systems with negative damping [11]. Our finding provides the first direct evidence for power amplification in the mammalian cochlea. The finding also makes redundant current hypotheses of cochlear frequency sharpening and sensitization that are not based on negative damping.

Original languageEnglish
Pages (from-to)1340-1344
Number of pages5
JournalCurrent Biology
Volume17
Issue number15
DOIs
Publication statusPublished - 7 Aug 2007

Keywords

  • SYSNEURO

Fingerprint Dive into the research topics of 'Power Amplification in the Mammalian Cochlea'. Together they form a unique fingerprint.

  • Cite this