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Dear List, Regarding Brian and Jan’s interesting exchange on prenatal hearing, I think one informative fact about prenatal hearing is that a newborn can recognize a tune
heard prenatally. I describe one of these studies in Music, Language, and the Brain (p. 382-383): “Hepper (1991) had one group of mothers listen to a particular tune once or twice a day throughout their pregnancy, whereas another group of mothers did not listen to this tune. Newborns from the prior group recognized the tune, as indicated by changes in heart rate, movement, and alertness upon hearing the tune after birth (the control group showed no such changes). To ascertain if the newborns were responding on the basis of the specific tune (or if prior exposure to music simply made them more responsive to music in general), Hepper conducted another study in which mothers listened to the same tune during pregnancy, but babies were tested with a different tune or a backward version of the original tune. In this case, the newborns did not show any sign of recognition. Hepper went on to show that selective response to the familiar tune could be observed even
before birth
(via ultrasound monitoring of fetal movement), at 36–37 weeks of gestational age. Hepper did a final study with 29- 30-week-old fetuses, showing that there was no evidence of tune recognition at this age.” Hepper, P. G. (1991). An examination of fetal learning before and after birth.
The Irish Journal of Psychology,
12:95–107. Regards, Ani Patel Aniruddh D. Patel Associate Professor Dept. of Psychology 490 Boston Ave. Medford, MA 02155 a.patel@xxxxxxxxx http://ase.tufts.edu/psychology/People/patel/ From: AUDITORY - Research in Auditory Perception [mailto:AUDITORY@xxxxxxxxxxxxxxx]
On Behalf Of Monson, Brian Dear List, In case it might be useful to anyone else, please see my response to Jan's question below. Best, Brian Brian B. Monson, PhD Research Fellow | Department of Pediatric Newborn Medicine Brigham and Women's Hospital | Harvard Medical School Phone: +617 525 4131 | Email: bmonson@xxxxxxxxxxxxxxxxxxxxxxxx On Mar 2, 2015, at 5:32 PM, Brian Monson <BMONSON@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Dear Jan, Fetal hearing is certainly a complicated issue. I've seen several individuals at conferences refer to the intrauterine environment as simply a 500-Hz low-pass filter, which doesn't appear to be entirely accurate. Another point sometimes
brought up is that, to a first approximation, intrauterine hearing should mimic underwater hearing, which stimulates the inner ear primarily via bone conduction (Hollien, 1973, JASA, 53:1288-1295). However, I think we need to be cautious about bone conduction
for children and adults vs. a fetus whose bones (including the ossicles) aren't completely ossified. On the other hand, inner ear stimulation could occur entirely via fluid rather than bone (Perez et al, 2011, Hearing Research, 280:82-85). To your specific question, the middle ear of the fetus is fluid filled, which will likely dampen whatever mechanical forces the non-ossified ossicles might provide. Further complicating the process, however, the (incompressible) fluid
in the middle ear would also provide another direct acoustic pathway from the tympanic membrane to both the oval window and round window. Theoretically this pathway is also present via the airspace when the middle ear is filled with air, but I suppose it
typically gets ignored because the ossicles would dominate oval window actuation. That might not be true of cartilaginous ossicles in a fluid-filled middle ear space. In any event, fetuses have been reported to develop sensitivity to low frequencies first, followed by high frequencies (Hepper & Shahidullah, 1994, "The development of fetal hearing"), so the question of what the cochlea picks up is highly
dependent on the gestation time point of interest. Gerhardt & Abrams have a review on fetal hearing that you might already have, but I'm attaching just in case. I hope this is helpful. I'd be interested to hear any input you might get from others. Best, Brian Brian B. Monson, PhD Research Fellow | Department of Pediatric Newborn Medicine Brigham and Women's Hospital | Harvard Medical School Phone: +617 525 4131 | Email: bmonson@xxxxxxxxxxxxxxxxxxxxxxxx On Mar 1, 2015, at 2:22 PM, Jan Schnupp <jan.schnupp@xxxxxxxxxxxxx> wrote:
Dear List, I was looking around for literature describing the intra-uterine sound environment of unborn fetuses and came across this paper which suggests that sound in the uterus - if measured with a hydrophone - is essentially unattenuated relative to the source of air born sound and shows apparently no low-passing. That would suggest that sound in utero is essentially crystal
clear and not "muffled" as one might perhaps intuitively suspect. However, as I was pondering this I wondered: what about the middle ear of unborn children? Are they filled with (amniotic?) fluid? Or with air? And does it matter? How good could we expect the
cochlea in the unborn to be at picking up sound from the amniotic fluid, and does that depend on whether the middle ear is fluid or air filled? Best wishes, Jan -- Prof Jan Schnupp <Gerhardt_2000_Fetal Exposures to Sound and Vibroacoustic Stimulation.pdf> The information in this e-mail is intended only for the person to whom it is |