On the use of Acoustic Middle ear Muscle Reflexes in Studies of Auditory Function in Non-Anesthetized Rabbits

Abstract

Use of the acoustic middle ear reflexes for studies of the function of the auditory pathways in non-anesthetized animals was investigated. Middle ear muscle activity was recorded in rabbits as changes of the acoustic impedance at the eardrum. The stimulus-response curves were found to be well described by the Gaussian distribution function with mean value A and variance B². The reproducibility of the stimulus-response curves of the ipsilateral middle ear reflex obtained from repeated measurements was statistically analysed. The standard deviation was 1.9 dB for the position along the intensity axis (A) and 1.0 dB for the slope of the curve (B). The variability of the reflex recording in repeated measurements during single experimental sessions was on the order of 1.0 dB (A). The optimal measuring tone intensity range was between 66 and 72 dB SPL.