Document Detail


The effects of experimentally induced conductive hearing loss on spectral and temporal aspects of sound transmission through the ear.
MedLine Citation:
PMID:  21073935     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Conductive hearing loss (CHL) is known to produce hearing deficits, including deficits in sound localization ability. The differences in sound intensities and timing experienced between the two tympanic membranes are important cues to sound localization (ILD and ITD, respectively). Although much is known about the effect of CHL on hearing levels, little investigation has been conducted into the actual impact of CHL on sound location cues. This study investigated effects of CHL induced by earplugs on cochlear microphonic (CM) amplitude and timing and their corresponding effect on the ILD and ITD location cues. Acoustic and CM measurements were made in 5 chinchillas before and after earplug insertion, and again after earplug removal using pure tones (500 Hz to 24 kHz). ILDs in the unoccluded condition demonstrated position and frequency dependence where peak far-lateral ILDs approached 30 dB for high frequencies. Unoccluded ear ITD cues demonstrated positional and frequency dependence with increased ITD cue for both decreasing frequency (±420 μs at 500 Hz, ±310 μs for 1-4 kHz) and increasingly lateral sound source locations. Occlusion of the ear canal with foam plugs resulted in a mild, frequency-dependent conductive hearing loss of 10-38 dB (mean 31 ± 3.9 dB) leading to a concomitant frequency dependent increase in ILDs at all source locations. The effective ITDs increased in a frequency dependent manner with ear occlusion as a direct result of the acoustic properties of the plugging material, the latter confirmed via acoustical measurements using a model ear canal with varying volumes of acoustic foam. Upon ear plugging with acoustic foam, a mild CHL is induced. Furthermore, the CHL induced by acoustic foam results in substantial changes in the magnitudes of both the ITD and ILD cues to sound location.
Authors:
J Eric Lupo; Kanthaiah Koka; Jennifer L Thornton; Daniel J Tollin
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2010-11-10
Journal Detail:
Title:  Hearing research     Volume:  272     ISSN:  1878-5891     ISO Abbreviation:  Hear. Res.     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-02-14     Completed Date:  2011-06-07     Revised Date:  2012-02-02    
Medline Journal Info:
Nlm Unique ID:  7900445     Medline TA:  Hear Res     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  30-41     Citation Subset:  IM    
Copyright Information:
Copyright © 2010 Elsevier B.V. All rights reserved.
Affiliation:
Department of Otolaryngology, University of Colorado Denver, Aurora, CO, USA. james.lupo@ucdenver.edu
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MeSH Terms
Descriptor/Qualifier:
Acoustic Stimulation
Animals
Audiometry, Pure-Tone
Auditory Threshold
Chinchilla
Cochlea / physiopathology*
Cochlear Microphonic Potentials
Cues*
Disease Models, Animal
Ear Protective Devices
Female
Hearing Loss, Conductive / etiology,  physiopathology*
Male
Pressure
Sound Localization*
Sound Spectrography
Time Factors
Time Perception*
Grant Support
ID/Acronym/Agency:
5T32HD041697-08/HD/NICHD NIH HHS; P30 NS048154-05/NS/NINDS NIH HHS; R01 DC006865-06/DC/NIDCD NIH HHS; R01DC006865/DC/NIDCD NIH HHS

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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