Table II.

Theoretical intact-bulla low-frequency stapes displacement per unit pressure for cat, guinea pig, and chinchilla. Stapes displacement was computed using Eqs. (1)–(3). The “effective” tympanic-membrane areas were taken to be 2/3 of the listed (anatomical) areas. The second stapes displacement value for the guinea pig and the second and third values for the chinchilla were computed using averages of the two areas listed, in each case, for guinea pig and chinchilla (effective areas of 0.19 and 0.35 cm², respectively). Lever ratios used for cat, guinea pig, and chinchilla were 2, 2, and 2.38, respectively.

	Middle-ear volume(cm3)	Tympanic membrane area(cm2)	Stapes displacement per unit pressure(10−6 cm/dyn)
Cat
Lynch, 1981	0.89
Wever et al., 1948		0.42	0.51
Guinea pig
Mundie, 1963	0.25	0.25	0.45
Teas and Nielsen, 1975	0.20		0.32
Wilson and Johnstone, 1975	0.31	0.32	0.44
Chinchilla
von Bismarck, 1967	1.2	0.50	0.90
Drescher and Eldredge, 1974	2.2		1.56
Teas and Nielsen, 1975	2.8		1.98
Vrettakos et al., 1988	1.5	0.56	1.00