Function and Acoustics of the Normal and Diseased Middle Ear

Abstract

The middle ear helps convert compressional sound waves in the ear canal into transverse traveling waves in the cochlea. This chapter presents a conceptual framework for understanding middle ear function. The framework is first developed for the normal middle ear and then modified to include several pathological conditions. Data describing energy transfer between the ear canal and the cochlea are reviewed, including impedance measures, ossicular motions, and cochlear pressure measurements. The functions of individual parts of the normal middle ear are discussed for the tympanic membrane, the malleus and incus complex, the stapes, and the middle ear cavity. The effects of specific middle ear pathologies are discussed, including those affecting the middle ear cavity, the tympanic membrane, and the ossicles. Whenever possible, the diseases are represented by modifying the conceptual model of the normal middle ear.