Document Detail


The pathway enabling external sounds to reach and excite the fetal inner ear.
MedLine Citation:
PMID:  11474136     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The human fetus in utero is able to respond to sounds in the amniotic fluid enveloping the fetus after about 20 weeks gestation. The pathway by which sound reaches and activates the fetal inner ear is not entirely known. It has been suggested that in this total fluid environment, the tympanic membrane and the round window membrane become 'transparent' to the sound field, enabling the sounds to reach the inner ear directly through the tympanic membrane and the round window membrane. It is also possible that sounds reach the inner ear by means of tympanic membrane--ossicular chain--stapes footplate conduction (as in normal air conduction). There is also evidence that sounds reach the fetal inner ear by bone conduction. Several animal and human models of the fetus in utero were studied here in order to investigate the pathway enabling sounds to reach and activate the fetal inner ear. This included studying the auditory responses to sound stimuli of animals and humans under water. It was clearly shown in all the models that the dominant mechanism was bone conduction, with little if any contribution from the external and middle ears. Based on earlier experiments on the mechanism and pathway of bone conduction, the results of this study lead to the suggestion that the skull bone vibrations induced by the sound field in the amniotic fluid enveloping the fetus probably give rise to a sound field within the fetal cranial cavity (brain and CSF) which reaches the fetal inner ear through fluid communication channels connecting the cranial cavity and the inner ear.
Authors:
H Sohmer; R Perez; J Y Sichel; R Priner; S Freeman
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Audiology & neuro-otology     Volume:  6     ISSN:  1420-3030     ISO Abbreviation:  Audiol. Neurootol.     Publication Date:    2001 May-Jun
Date Detail:
Created Date:  2001-07-27     Completed Date:  2001-10-04     Revised Date:  2005-11-17    
Medline Journal Info:
Nlm Unique ID:  9606930     Medline TA:  Audiol Neurootol     Country:  Switzerland    
Other Details:
Languages:  eng     Pagination:  109-16     Citation Subset:  IM    
Copyright Information:
Copyright 2001 S. Karger AG, Basel
Affiliation:
Department of Physiology, Hebrew University Hadassah Medical School, Jerusalem, Israel. sohmer@md2.huji.ac.il
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MeSH Terms
Descriptor/Qualifier:
Animals
Auditory Pathways / embryology*
Auditory Perception / physiology*
Auditory Threshold / physiology
Bone Conduction / physiology
Ear, Inner / embryology*
Embryonic and Fetal Development / physiology*
Evoked Potentials, Auditory, Brain Stem / physiology
Fetus / physiology*
Gerbillinae
Guinea Pigs
Hearing / physiology
Rats
Sound*

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


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