Tympanic Membrane Collagen Fibers: A Key to High-Frequency Sound Conduction§

Authors

  • Kevin N. O'Connor MEng,

    1. From the Department of Mechanical Engineering, Stanford University, Stanford, California, U.S.A.
    2. Department of Otolaryngology/Head and Neck Surgery, Stanford University, Stanford, California, U.S.A.
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  • Majestic Tam MD,

    1. Department of Otolaryngology/Head and Neck Surgery, Stanford University, Stanford, California, U.S.A.
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  • Nikolas H. Blevins MD,

    1. Department of Otolaryngology/Head and Neck Surgery, Stanford University, Stanford, California, U.S.A.
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  • Sunil Puria PhD

    Corresponding author
    1. From the Department of Mechanical Engineering, Stanford University, Stanford, California, U.S.A.
    2. Department of Otolaryngology/Head and Neck Surgery, Stanford University, Stanford, California, U.S.A.
    • Sunil Puria, Stanford University, Mechanics and Computation, 496 Lomita Mall, Durand Building, Room 206, Stanford, CA 94305
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  • k.n.o. and m.t. contributed equally to this Manuscript.

  • This work was conducted at the Palo Alto VA Hospital (Palo Alto, California), and at Stanford University, Stanford, California, U.S.A.

  • §

    Presented at the American Academy of Otolaryngology–Head and Neck Surgery meeting, in Toronto, Ontario, Canada, September 2006.

Abstract

Objective: To investigate the significance of tympanic membrane collagen fiber layers in high frequency sound transmission.

Study Design: Human cadaver temporal bone study.

Methods: Laser Doppler vibrometry was used to measure stapes footplate movement in response to acoustic stimulation. The tympanic membrane was altered by creating a series of slits and applying paper patches to isolate the effects of specifically oriented collagen fibers. Three groups of membrane alterations were evaluated: 1) circumferentially oriented slits involving each quadrant to primarily disrupt radial fibers, made sequentially within superior-anterior, inferior-anterior, inferior-posterior, and superior-posterior quadrants; 2) the same slits made in the reverse order; and 3) radially oriented slits from the umbo to the annulus to primarily disrupt circumferential fibers. For each group, measurements of the middle-ear cavity pressure, ear canal pressure, and stapes velocity were made each time the tympanic membrane was altered.

Results: Regardless of the order in which the circumferentially oriented slits were made, there was a consistent decrease in stapes velocity above 4 kHz for the third and fourth cuts compared to the control. The mean decrease in the range of 4 to 12.5 kHz was 11 dB for the third patched slit and 14 dB for the fourth patched slit (P < .01). Radially oriented slits appear to produce smaller effects.

Conclusions: Radial collagen fibers in the tympanic membrane play an important role in the conduction of sound above 4 kHz.

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