Effect of Middle Ear Modification on Umbo Vibration: Human Temporal Bone Experiments With a New Vibration Measuring System

Sound Pressure Gain Produced by the Human Middle Ear

“…Stapes footplate displacement decreased at a rate of − 12.1 dB/octave from 1.0 to 4.0 kHz and −13.0 dB/octave from 4.0 to 8.0 kHz. These peak‐to‐peak displacements are in agreement with data described in other publications 7‐10,16 . Data obtained above 9.0 kHz were not used for analysis because of a question of high‐frequency limitations in the sound‐generating ER‐2 transducer.…”

Acoustic Mechanisms

“…The volumes of the tympanic cavity estimated from the direct acoustic measurements and predicted from the impedance measurements are larger than those estimated from saline filling and from estimates published in the literature. The mean volume of the middle ear air space after blocking of the aditus by Gyo et al 2 was 0.51 ml, which is similar to previous estimates 5 , 16 . Our volume range of the tympanic cavity measured by saline filling was 0.56 to 0.85 ml; however, our acoustic measurements of this volume ranged from 0.74 to 2.26 ml and are consistent with our predicted volumes.…”

“…Our results indicate that canal wall-down compared with a canal wall-up mastoidectomy leads to a 1 to 5 dB decrease in middle ear sound transmission below 1 kHz, a 0 to 10 dB increase between 1 kHz and 3 kHz, and little change above 3 kHz. These results are similar in magnitude and direction to those reported by Gyo et al, 2 who compared the effect of the canal wall-up mastoidectomy to the effect of the canal wall-down mastoidectomy using umbo displacement as a measure of middle ear sound transmission (Fig. 9).…”

Paper patching of the tympanic membrane as a symptomatic treatment for patulous eustachian tube syndrome

“…10 The opening of the middle-ear cavity in cadaver temporal bones has been shown to increase the admittance of low-to mid-frequency acoustic input. 11,12 The same effect has been demonstrated in the gerbil, using a small hole of only 1.2 mm in diameter (Figure 3). 13 Based on the findings of these studies, it is reasonable to assume that the loss of the air cushion (associated with a wide open eustachian tube) in patulous eustachian tube patients produces a similar effect, in which there is a downward shift of tympanic membrane resonance frequency, or an increase in the admittance of low-to mid-frequency acoustic input at the tympanic membrane.…”