Plugging the Ear Leads to the Perception of Phantom Sounds

Nothing new really I guess, 18 healthy participants with normal hearing and no tinnitus were recruited to wear an earplug in one ear for 7 days.

The earplugs simulated a mild high-frequency hearing loss.

14 out of the 18 reported phantom sounds during earplug use.

The spectra showed that the phantom sounds were mostly perceived as high-pitched, corresponding to the frequency range most affected by the earplug.

What's of course interesting is that not everybody (4 of the 18) reported phantom sounds, just like not everybody with hearing loss reports tinnitus.

"In future studies, we thus plan to look for differences between participants who hear phantom sounds and those who don't. Maybe we'll be able to find the "off switch" for tinnitus that way."



http://www.ncbi.nlm.nih.gov/pubmed/22675466
PDF about the study: http://www.tinnitusresearch.org/en/...usResearchArticleSeries_forTRI_5_Schaette.pdf

PLoS One. 2012;7(6):e35238. doi: 10.1371/journal.pone.0035238. Epub 2012 Jun 4.
Reversible induction of phantom auditory sensations through simulated unilateral hearing loss.
Schaette R, Turtle C, Munro KJ.

Source
Ear Institute, University College London, London, United Kingdom. r.schaette@ucl.ac.uk

Abstract
Tinnitus, a phantom auditory sensation, is associated with hearing loss in most cases, but it is unclear if hearing loss causes tinnitus. Phantom auditory sensations can be induced in normal hearing listeners when they experience severe auditory deprivation such as confinement in an anechoic chamber, which can be regarded as somewhat analogous to a profound bilateral hearing loss. As this condition is relatively uncommon among tinnitus patients, induction of phantom sounds by a lesser degree of auditory deprivation could advance our understanding of the mechanisms of tinnitus. In this study, we therefore investigated the reporting of phantom sounds after continuous use of an earplug. 18 healthy volunteers with normal hearing wore a silicone earplug continuously in one ear for 7 days. The attenuation provided by the earplugs simulated a mild high-frequency hearing loss, mean attenuation increased from <10 dB at 0.25 kHz to >30 dB at 3 and 4 kHz. 14 out of 18 participants reported phantom sounds during earplug use. 11 participants presented with stable phantom sounds on day 7 and underwent tinnitus spectrum characterization with the earplug still in place. The spectra showed that the phantom sounds were perceived predominantly as high-pitched, corresponding to the frequency range most affected by the earplug. In all cases, the auditory phantom disappeared when the earplug was removed, indicating a causal relation between auditory deprivation and phantom sounds. This relation matches the predictions of our computational model of tinnitus development, which proposes a possible mechanism by which a stabilization of neuronal activity through homeostatic plasticity in the central auditory system could lead to the development of a neuronal correlate of tinnitus when auditory nerve activity is reduced due to the earplug.