Document Detail

Fetal sheep in utero hear through bone conduction.
MedLine Citation:
PMID:  8944295     Owner:  NLM     Status:  MEDLINE    
PURPOSE: Although the air-conduction pathway is the principal mode of sound transmission to the inner ear, this may not be true for the fetus in utero. The fetus detects and responds to sounds in the maternal environment. Exogenous sounds can reach the fetal inner ear through the ear canal and middle ear system, bone conduction, or both. This study was designed to compare the effectiveness of these two routes of sound transmission by recording cochlear microphonic potentials from the fetus in utero in response to airborne sounds. MATERIALS AND METHODS: Cochlear microphonics (CMs) recorded from one round window (RW) of fetal sheep in utero were obtained in three conditions: (1) head uncovered; (2) head covered with a neoprene hood; and (3) head covered with a neoprene hood fashioned with a hole that permitted the pinna and ear canal to be exposed. Tone bursts (0.5, 1.0, and 2.0 kHz) were delivered through a loudspeaker at high intensities (100 to 135 dB sound pressure level) to the flank of the ewe. CMs were detected with indwelling electrodes, amplified, and averaged. CM input-output functions were obtained from the fetus in each of the three conditions described above. RESULTS: CMs recorded with the head uncovered were more sensitive than were the CMs recorded with the hood in place. There was no difference in sensitivity between the condition during which the head was completely covered and the condition in which the pinna and ear canal are exposed. CONCLUSION: The principal mode of sound transmission into the fetal inner ear is through bone conduction.
K J Gerhardt; X Huang; K E Arrington; K Meixner; R M Abrams; P J Antonelli
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  American journal of otolaryngology     Volume:  17     ISSN:  0196-0709     ISO Abbreviation:  Am J Otolaryngol     Publication Date:    1996 Nov-Dec
Date Detail:
Created Date:  1997-03-06     Completed Date:  1997-03-06     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8000029     Medline TA:  Am J Otolaryngol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  374-9     Citation Subset:  IM    
Department of Communication Processes and Disorders, University of Florida, Gainesville 32611, USA.
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MeSH Terms
Acoustic Stimulation / instrumentation,  methods
Bone Conduction / physiology*
Cochlear Microphonic Potentials / physiology
Ear, External / embryology,  physiology
Ear, Middle / embryology,  physiology
Fetus / physiology*
Grant Support

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