An Experimental Study of Middle-ear Vibrations in Rats

Hearing impairment is one of the most common disabilities. Animal models have been shown to be valuable tools in auditory research, including studies of middle-ear mechanics. Rats are potentially very useful for this purpose. They are low in cost, they are genetically similar to humans, and the middle-ear structures are easily approachable. The goal of the present study is to characterize the frequency response of the rat tympanic membrane. A laser Doppler vibrometer was used to measure the vibrations of the tympanic membrane. Measurements were done on two female Sprague Dawley rats. The tympanic membrane was stimulated with 45 pure-tone sine waves between 250 and 8000 Hz in Rat #1 and with a slowly sweeping signal from 200 – 10 000 Hz in Rat #2. Results at the umbo compare well with previous studies. The first measurements of the frequency response of the rat tympanic membrane at points other than the umbo are also presented.