Comment on "Wave model of the cat tympanic membrane" [J. Acoust. Soc. Am. 122(2), 918-931 (2007)].

The tympanic membrane model as developed by Parent and Allen [(2007). J. Acoust. Soc. Am. 122(2), 918-931] is shown to have active, lossy, and non-reciprocal properties despite being described as lossless. These properties are traced back to its scattering junction formulations. Some impedance parameters are shown to have ambiguous values which complicate interpreting the physics of the model's internal wave propagation. Certain model parameters omitted from the original paper have been derived from the original computer simulation source code used by Parent and Allen.