Effect of middle ear fluid on sound transmission and auditory brainstem response in XXXX .

@entity2171 @entity840 @entity2172 @entity2170
Combined measurements of @entity2172 and auditory brainstem response (ABR) in live @entity840 with @entity2171 ( @entity2171 ) are reported in this paper. The @entity2171 model was created by injecting saline into the middle ear cavity. Vibrations of the tympanic membrane (TM), the tip of the incus, and the round window membrane (RWM) were measured with a laser vibrometer at frequencies of 0.2-40  kHz when the middle ear fluid increased from 0 to 0.2  ml (i.e., full fill of the cavity). The click and pure tone ABRs were recorded as the middle ear fluid increased. Fluid introduction reduced mobility of the TM, incus and RWM mainly at high frequencies (f  >  1  kHz). The magnitude of this reduction was related to the volume of fluid. The displacement transmission ratio of the TM to incus varied with frequency and fluid level. The volume displacement ratio of the oval window to round window was approximately 1.0 over most frequencies. Elevation of ABR thresholds and prolongation of ABR latencies were observed as fluid level increased. Reduction of TM displacement correlated well with elevation of ABR threshold at 0.5-8  kHz. Alterations in the ratio of @entity2170 before and after fluid induction are consistent with fluid-induced changes in complex ossicular motions.
