Body Inversion and the Acoustic Immittance of the Ear The effect of body inversion on the acoustic immittance of normal ears was investigated by means of admittance tympanometry at a probe-tone frequency of 660 Hz. In the upright position, maximum acoustic admittance at the tympanic membrane occurred when the air pressure in the external meatus was close to atmospheric ... Research Article
Research Article  |   June 01, 1974
Body Inversion and the Acoustic Immittance of the Ear
 
Author Affiliations & Notes
  • J. H. Macrae
    National Acoustic Laboratories, Sydney, Australia
Article Information
Research Articles
Research Article   |   June 01, 1974
Body Inversion and the Acoustic Immittance of the Ear
Journal of Speech, Language, and Hearing Research, June 1974, Vol. 17, 310-320. doi:10.1044/jshr.1702.310
History: Received December 19, 1973 , Accepted February 14, 1974
 
Journal of Speech, Language, and Hearing Research, June 1974, Vol. 17, 310-320. doi:10.1044/jshr.1702.310
History: Received December 19, 1973; Accepted February 14, 1974

The effect of body inversion on the acoustic immittance of normal ears was investigated by means of admittance tympanometry at a probe-tone frequency of 660 Hz. In the upright position, maximum acoustic admittance at the tympanic membrane occurred when the air pressure in the external meatus was close to atmospheric pressure. In the inverted position, the admittance at the membrane was considerably reduced when the meatal air was at atmospheric pressure and maximum admittance occurred at a meatal air pressure of about 53 mm H2O, with the resistive component reduced and the reactive component slightly increased relative to their values in the upright position. When the middle-ear air pressure in the inverted position was equalized with the ambient atmospheric pressure, the maximum admittance at the membrane occurred at a meatal air pressure of 10–20 mm H2O and the reduction in conductance and slight increase in susceptance persisted. It was concluded that the effect of body inversion on the acoustic immittance of the ear is due largely to an increase in the air pressure in the middle-ear cavity (which is probably produced by an increase in the volume of the mucosa lining the cavity) and to a small extent to another overpressure which probably occurs in the labyrinthine fluids.

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