Several years ago, neuroscientists Bradley Voytek and Tim Verstynen merged their love of science and zombies in their book Do Zombies Dream of Undead Sheep? In the book, Voytek and Verstynen consider many of the common zombie phenotypical presentations: slow unsteady gait, slurred speech, hunger, cognition issues, etc. For example, they report that zombies have classic signs of Wernicke’s aphasia, hence their inability to communicate outside of constant moaning. While according to Voytek and Verstynen the zombie brain has issues, they claim their senses and motor control remain intact. Voytek and Verstynen provide a reasonable explanation for the zombies excellent sense of smell, but normal hearing? Here, we can agree to disagree.
Any audiologist or hearing scientist worth their weight in cerumen is familiar with the work of George von Bekesy see Békésy G. Zur Theorie des Hörens; die Schwingungsform der Basilarmembran. Phys Zeits. 1928;29:793–810.
Bekesy’s experimental demonstration of the cochlear traveling wave in 1928 was pioneering; yet, the high stimulus levels and the post-mortem preparations confounded his findings. It would be many years later before the demonstration of cochlear amplification and hair cell motility would be demonstrated in in vivo preparations. Nonetheless, maybe Bekesy’s work can provide insight on our zombie conundrum.
It is well described that zombies maintain some level of neurological function in the reanimation process, but they have limited to no vascular function and their body fluids tend to be viscous in nature. Applying these physiological limitations to the inner ear we must conclude that zombies likely lack normal hearing sensitivity.
First, the lack of vascular supply likely limits the function of the stria vascularis resulting in atrophy and a compromised endocochlear potential. The diminished driving force would almost surely result in outer hair cell dysfunction. Second, the increased viscosity of the cochlear fluids would also likely further compromise mechanotransduction and activation of either the outer hair cell or the inner hair cell.
Yet, the intact nature of the neural portion of the system may still allow some level of hearing. If consistent with Bekesy’s work we can assume that the zombie likely has a lack of cochlear amplification and loss of non-linearity compromising both sensitivity and dynamic range. Applying Bekesy’s post-mortem data we can estimate that zombies likely have at least a moderately-severe sensorineural hearing loss. It is also plausible that loss of non-linearity and elevated thresholds may compromise loudness growth leading to sound sensitivity (recruitment/hyperacusis). This sound sensitivity may supplement the excellent smell ability in zombies in localizing food (i.e. Brains, Brains, BRAINS).
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