Dr. Matthew Mason: Further Information...
University Physiologist Tel: +44 (0)1223 333829, Fax: +44 (0)1223 333840, E-mail: mjm68@cam.ac.uk
Mason, M.J. (2016) Structure and function of the mammalian middle ear. II: Inferring function from structure. Journal of Anatomy 228: 300-312.
The study of middle ear function involves principles of acoustics which are unfamiliar to many biologists. The aim of this paper is to introduce this field to those who have little background in the physical sciences. Simple, "textbook" models of impedance matching have used by many zoologists in their studies of middle ear function in a diverse range of animals, and have even been used by palaeontologists to interpret the function of fossil ears from extinct creatures. Predictions from such models are compared to recent experimental data obtained from Meriones unguiculatus, the Mongolian gerbil, published in the specialized, hearing physiology literature. Many of the simple predictions obtained from anatomical measurements are found to be seriously inaccurate because of the questionable assumptions behind these models, which are spelled out here. Electrical analogue models represent an alternative way to examine middle ear function, at least at low frequencies, and they are introduced and explained. The recent proposal that the ossicles may work as a "transmission line" is discussed. It is concluded that anatomical measurements are most likely to yield useful predictions about auditory function at low frequencies, middle ear cavity volume being perhaps the most useful single measurement that can be made.
The companion paper to this article describes middle ear structures in a range of small, desert mammals including the key model species Meriones, providing the anatomical background for this paper.
This article is available on the Journal of Anatomy website: please click here to access it.
Please contact me if you would like to be sent a reprint copy of this paper.