Network Model for the Human Middle Ear

Abstract

The purpose of this work is to offer a contribution to network modelling of the human middle ear. The model proposed has been successfully adapted to the following empirical frequency characteristics: 1) stapes displacement per unit sound pressure at the eardrum, 2) sound pressure increase from ear canal entrance to the tympanic membrane, 3) acoustic impedance at the eardrum for a normal ear, an otosclerotic ear, and an ear with interrupted incudo-stapedial joint. The acoustical energy reflectance at the eardrum, as calculated from a model of the ear canal when terminated by the middle ear model, agrees reasonably well with experimental data up to about 12 kHz. Satisfactory agreement between model results and experimental data has also been achieved for the sound pressure transformation in the middle ear. Stapedius muscle contraction is simulated by changing a single parameter. It is concluded that further progress in middle ear model development requires a strengthening of the empirical basis.

An Analysis of the Acoustic Input Impedance of the Ear

“…O'Connor and Puria (2008) modeled the cochlear input impedance as resistive, consistent with Zwislocki's suggestion that the cochlear input impedance is predominantly resistive, although there is a compliant reactance element (Aibara et al 2001). Kringlebotn (1988) included compliant reactance and mass reactance terms for the cochlea in his model.…”

“…Previous studies of the acoustic input impedance of the ear include lumped element models of the human middle ear (e.g., Kringlebotn 1988;Moller 1961;Zwislocki 1962), experimental studies of the middle ear of human temporal bones (e.g., O'Connor and Puria 2008;Voss et al 2000), experimental studies of human ears (e.g., Farmer-Fedor and Rabbitt 2002;Kringlebotn 1994;Margolis et al 1999;Moller 1965;Rabinowitz 1981;Voss and Allen 1994), and models and experimental studies of animal ears (e.g., Huang et al 2000;Lynch et al 1994;Parent and Allen 2007). Prior to 1981, experimental studies of the acoustic input impedance of the ear in humans were limited to about 1.5 kHz, the ear canal treated as an acoustic compliance (Rabinowitz 1981).…”

“…The ear canal, modeled as a one-dimensional transmission line, extends the upper frequency limit to where sound deviates from propagating predominantly as plane waves. Kringlebotn (1988) modeled the human ear canal as a lossy transmission line terminated by a load impedance, the middle ear, and the cochlea. His middle ear model was similar to that of Zwislocki (1962), incorporating the middle ear cavities, eardrum and ossicles, cochlea, and shunts for energy reflected from the middle ear and not transferred to the cochlea.…”

“…His middle ear model was similar to that of Zwislocki (1962), incorporating the middle ear cavities, eardrum and ossicles, cochlea, and shunts for energy reflected from the middle ear and not transferred to the cochlea. Kringlebotn (1988) obtained values for his model elements from published studies for element values that were fixed in the model and used a method of least squares to fit the model to the data average obtained from human temporal bones for model elements that were free to vary. O'Connor and Puria (2008) examined transfer functions of the middle ear using a model that did not include the ear canal or cavities of the middle ear, focusing on the function of the transmission of sound from the eardrum to the cochlea via the ossicular chain.…”

“…A modified version of Zwislocki's model of the middle ear was used with the eardrum incorporated as a delay line. As for Kringlebotn (1988), parameters for the model were obtained by fitting the model to data from human temporal bones. O'Connor and Puria (2008) modeled the cochlear input impedance as resistive, consistent with Zwislocki's suggestion that the cochlear input impedance is predominantly resistive, although there is a compliant reactance element (Aibara et al 2001).…”