Transmission matrix analysis of the chinchilla middle ear.

Despite the common use of the chinchilla as an animal model in auditory research, a complete characterization of the chinchilla middle ear using transmission matrix analysis has not been performed. In this paper we describe measurements of middle-ear input admittance and stapes velocity in ears with the middle-ear cavity opened under three conditions: intact tympano-ossicular system and cochlea, after the cochlea has been drained, and after the stapes has been fixed. These measurements, made with stimulus frequencies of 100-8000 Hz, are used to define the transmission matrix parameters of the middle ear and to calculate the cochlear input impedance as well as the middle-ear output impedance. This transmission characterization of the chinchilla middle ear will be useful for modeling auditory sensitivity in the normal and pathological chinchilla ear. (c) 2007 Acoustical Society of America.