Current and Emerging Tools for the Assessment of Middle-Ear Function The ANSI (1987) standard for immittance instruments calls for the use of a 226-Hz probe tone for measuring middle ear function. Acoustic admittance (Y) is a complex quantity made up of susceptance (the ease of sound flow which is affected by energy storage due to stiffness or mass) and ... Article
Article  |   November 01, 2004
Current and Emerging Tools for the Assessment of Middle-Ear Function
Author Affiliations & Notes
  • M. Patrick Feeney
    V.M. Bloedel Hearing Research Center, University of Washington, Seattle, WA
Article Information
Hearing Disorders / Articles
Article   |   November 01, 2004
Current and Emerging Tools for the Assessment of Middle-Ear Function
SIG 6 Perspectives on Hearing and Hearing Disorders: Research and Diagnostics, November 2004, Vol. 8, 4-7. doi:10.1044/hhd8.2.4
SIG 6 Perspectives on Hearing and Hearing Disorders: Research and Diagnostics, November 2004, Vol. 8, 4-7. doi:10.1044/hhd8.2.4
The ANSI (1987) standard for immittance instruments calls for the use of a 226-Hz probe tone for measuring middle ear function. Acoustic admittance (Y) is a complex quantity made up of susceptance (the ease of sound flow which is affected by energy storage due to stiffness or mass) and conductance (the ease of sound flow which is affected by dissipation of energy through the system—like friction in the mechanical world). Admittance has an inverse term, impedance (Z=1/Y), which is the resistance to sound flow. The 226 Hz probe tone works well in this schema, because the flow of energy at this low frequency is mostly opposed by stiffness (versus mass at high frequencies), and in human ears (with the exception of infant ears) most of the disorders we are trying to detect affect this stiffness in a predictable way. Well, that’s the theory anyway.
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