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FW: prenatal auditory localization

I forwarded the message to a colleague with considerable experience with
prenatal hearing research and here is his reply. Hope this helps!

-----Original Message-----
From: Ken Gerhardt [mailto:gerhardt@ufl.edu] 
Sent: Wednesday, August 25, 2004 11:33 AM

  Human fetuses are in a fluid environment. Sound travels about 4 times
faster in water than in air.  Experiments using scuba divers show that they
are unable to localize sound.  I actually served as a subject for some of
these experiments 20-25 years ago.  I expect fetuses in utero cannot
localize sounds present in the maternal environment for this reason and
because they hear via bone conduction.  

References obtained from PubMed:

Gerhardt, K. J., & Abrams, R. M. (1996). Fetal hearing: characterization of
the stimulus and response. Semin Perinatol, 20(1), 11-20.

Gerhardt, K. J., Huang, X., Arrington, K. E., Meixner, K., Abrams, R. M., &
Antonelli, P. J. (1996). Fetal sheep in utero hear through bone conduction.
Am J Otolaryngol, 17(6), 374-379.

-----Original Message-----
From: AUDITORY Research in Auditory Perception
[mailto:AUDITORY@LISTS.MCGILL.CA] On Behalf Of Richard Parncutt
Sent: Wednesday, August 25, 2004 3:47 AM
Subject: prenatal auditory localization

Newborn infants can localize sound (at least left-right), and show it by
turning their head (Morongiello, JASA 1989). The question arises as to
whether they are using intensity or phase cues, and whether the ability is
somehow innate or already practiced before birth. From the point of view of
physics, intensity and phase cues should be available (if somewhat
impoverished) before birth, at least in the frequency range in which sounds
are audible to the fetus (say, 100-1000 Hz).

Does anyone know of experiments to investigate the possibility of fetal
sound localization? It might be as easy as studying lots of ultrasound
photos. Friendly gynecologists tend to chat to their expectant clients while
making ultrasound photos. According to the literature on prenatal hearing,
the sound of their voice should be audible to the fetus, although not as
loud as the mother's voice. If the fetus can localize, it may turn either
toward or away from the gynecologist. To find out if that is that case, one
could for example find out whether the gynecologist was on the left or right
side of the mother while making the ultrasound photos, and then compare that
information with photos in which the orientation of the fetus is clear. Has
anyone done anything like that?

Richard Parncutt, Ph.D., Professor of Systematic Musicology Department of
Musicology, University of Graz Mozartgasse 3,  A-8010 Graz (Austria/Europe)
Tel +43 316 380-2409 or -2405   Fax +43 316 380-9755
<lastname>@uni-graz.at   http://www-gewi.uni-graz.at/muwi/parncutt