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unacceptable when many elements of the ear exhibit a higher sensitivity than hearing. The wind industry should be held to the same high standards. Full-spectrum monitoring, which has been adopted in some reports, is essential.
In the coming years, as we experiment to better understand the effects of prolonged low-frequency sound on humans, it will be possible to reassess the roles played by acousticians and professional groups who partner with the wind industry. Given the present evidence, it seems risky at best to continue the current gamble that infrasound stimulation of the ear stays confined to the ear and has no other effects on the body. For this to be true, all the mechanisms we have outlined (low- frequency-induced amplitude modulation, low frequency sound-induced endolymph volume changes, infrasound stimulation of type II afferent nerves, infrasound exacerbation of noise-induced damage and direct infrasound stimulation of vestibular organs) would have to be insignificant. We know this is highly unlikely and we anticipate novel findings in the coming years that will influence the debate.
From our perspective, based on our knowledge of the physiol- ogy of the ear, we agree with the insight of Nancy Timmer- man that the time has come to “acknowledge the problem and work to eliminate it”.
References
Cheatham, M.A., Dallos, P. (2001). “Inner hair cell response patterns: implications for low-frequency hearing,” Journal of the Acoustical Society of America. 110, 2034-2044.
Drexl, M., Überfuhr, M., Weddell, T.D., Lukashkin, A.N., Wiegrebe, L., Krause, E., Gürkov, R. (2013). “Multiple Indices of the ‘Bounce’ Phenomenon Obtained from the Same Human Ears,” Journal of the Association for Research in Otolaryngology. (e-pub, before print copy) 10.1007/s10162- 013-0424-x
biosketches
Alec N. Salt is Professor of Otolaryn- gology at Washington University. He is a long-term member of the Acousti- cal Society of America, the Associa- tion for Research in Otolaryngology, and the American Otological Society. His research covers broad aspects of system-level cochlear physiology, with a major focus on the inner ear fluids,
drug delivery to the inner ear, and low-frequency sound ef- fects on the ear.
Jeffery T. Lichtenhan is Assistant
Professor of Otolaryngology at
Washington University in St. Louis.
He recently completed his postdoc-
toral fellowship in the Eaton-Peabody
Laboratory of Auditory Physiology at
Harvard Medical School. His research
addresses questions on the mechanics
of hearing to low-frequency acoustic
sound, and the auditory efferent system. Ultimately, his work aims to improve the differential diagnostics of sensorineural hearing loss.
Harding, G.W., Bohne, B.A., Lee S.C., Salt A.N. (2007). “Effect of infrasound on cochlear damage from exposure to a 4 kHz octave band of noise,” Hearing Research. 225:128-138.
Leventhall, G. (2006). “Infrasound From Wind Turbines – Fact, Fiction Or Deception,” Canadian Acoustics 34:29-36.
Leventhall, G. (2007). “What is infrasound?,” Progress in Biophysics and Molecular Biology 93: 130–137.
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