Energy reflectance in the ear canal can exceed unity near spontaneous otoacoustic emission frequencies

Edward M. Burns, Douglas H. Keefe, Robert Ling

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


There is some controversy in the literature over whether the so-called 'active mechanism' or 'cochlear amplifier' is actually a power amplifier that can produce an output signal with more power than its input, or whether it simply minimizes dissipative losses within the cochlea without providing an actual power gain greater than unity. A corollary of this controversy is whether spontaneous otoacoustic emissions (SOAEs) represent the output of a nonlinear oscillator mechanism, i.e., a power amplifier which can produce an oscillatory output signal in the absence of an input oscillatory signal, or whether they represent the output of a noise-driven, passive, nonlinear system. This paper describes measurements of energy reflectance and acoustic impedance in the ear canals of human subjects with strong SOAEs. The reflectance, and the resistive and reactive parts of the acoustic impedance, all show a frequency fine structure which correlates with SOAE frequencies, and which becomes more pronounced at low stimulus levels. In some ears at some SOAE frequencies energy reflectance exceeds unity, and correspondingly, acoustic resistance is negative. This result demonstrates that there is a power gain at these frequencies: The power reflected from the cochlea to the ear canal exceeds the power incident. It is also consistent with the theory that these SOAEs are produced by a nonlinear oscillator mechanism in the cochlea.

Original languageEnglish (US)
Pages (from-to)462-474
Number of pages13
JournalJournal of the Acoustical Society of America
Issue number1
StatePublished - 1998

ASJC Scopus subject areas

  • Arts and Humanities (miscellaneous)
  • Acoustics and Ultrasonics


Dive into the research topics of 'Energy reflectance in the ear canal can exceed unity near spontaneous otoacoustic emission frequencies'. Together they form a unique fingerprint.

Cite this