Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UF research adds to evidence that unborn children hear ’melody’ of speech

23.01.2004


It is well known that unborn babies can recognize their mothers’ voices and distinguish music from noise. But exactly what they hear remains unclear.



Now, scientists at the University of Florida have added a piece to the puzzle. In a series of unique experiments on a pregnant ewe designed to record exactly what sounds reach the fetal ear, UF research has bolstered previous findings suggesting that human fetuses likely hear mostly low-frequency rather than high-frequency sounds. That means they hear vowels rather than consonants and are more sensitive to the melodic parts of speech than to pitch, said Ken Gerhardt, a UF professor of communication sciences and disorders and an associate dean of the Graduate School.

As for music, "they’re not going to hear the violins, but they will hear the drums," said Gerhardt, who led the research reported in the November-December issue of the journal Audiology and Neuro Otology.


Anthony DeCasper, a professor of developmental psychology at the University of North Carolina-Greensboro, said the UF results are noteworthy because they were obtained from the inner ear, which presumably would register sounds exactly as a sheep fetus would hear them. The findings – which resulted from implanting a tiny electronic device in the inner ear of a fetal sheep that tapped into the signal the ear sends to the brain – dovetail with what other researchers have concluded based on less invasive studies involving human fetuses, he said.

"The way I put it is, the way the mother’s voice would sound in utero would be like Lauren Bacall speaking from behind a heavy curtain," DeCasper said.

The research also may have implications for the care of premature babies. Neonatal care units are traditionally relatively noisy places, replete with beeping machines and the hum of conversation, and research by Gerhardt, DeCasper and others is raising awareness and questions about how the sounds "premies" are exposed to may influence normal growth and development, researchers said.

Gerhardt said he began researching fetal hearing in response to inquiries from law enforcement agencies and the U.S. Navy. Both were concerned about how loud noises, such as gunfire or the rumble of a ship’s engine, could affect the hearing of babies being carried by pregnant servicewomen.

Gerhardt and Robert Abrams, a UF professor emeritus of obstetrics and gynecology, decided to study the issue using sheep because experiments by other researchers had shown that properties of sound transmission in pregnant women and sheep are similar. Their experiments revealed the womb dampened all but the loudest sounds. Even loud rock concerts are probably not noisy enough to pose a threat to fetal hearing development, Gerhardt said. The research, which has received more than $1 million from the Navy, the National Institutes of Health and the March of Dimes, contributed to federal workplace safety guidelines that today limit the duration of extremely loud noise exposure for pregnant women.

In their recently reported research, Gerhardt and Abrams focused specifically on the kinds of sounds fetal sheep hear. Their method was unique: They implanted an electronic "pickup" inside the inner ear of a fetal sheep, then played 64 recorded sentences on a loudspeaker in the open air near the mother sheep. The sounds the pickups detected were recorded and played back to 30 human adult listeners in order to determine how much or what portions of the sentences the fetus actually heard. For comparison, the researchers also placed a microphone inside the uterus of the ewe and in the open air, then performed identical tests with human listeners.

The results were surprising, with the intelligibility of sentences "actually much higher than we anticipated," Gerhardt said.

In part, that was unexpected because much of the noise that reaches a fetus comes from its mother’s own voice, movement, breathing and digestive processes. Even in a quiet room, the womb can be noisy place, he said. Also, fetuses don’t "hear" as much with their ears as children or adults do because their ears are filled with fluid, he said. Rather, much noise is transmitted to their inner ears through vibrations in their skulls. As a result, the mother’s voice tends to be the most dominant and recurring sound in the womb.

The listeners understood all of the sentences recorded in the open air, about 70 percent of the sentences recorded in the womb and about 30 percent of the sentences recorded in the fetal sheep’s inner ear.

The recordings revealed the reason the inner ear-recorded sentences proved so much less intelligible was that the higher-frequency consonants in words tended to be absent or confused. In other words, "ship" could easily be heard as "slit" or "sit." Lower-frequency vowels, by contrast, tended to penetrate the inner ear to a much greater extent.

Charlene Krueger, a UF assistant professor of nursing who works with premature babies, said that while a fetus hears its mother’s voice whenever she speaks and is insulated from higher frequencies, infants born prematurely don’t hear their mother’s voices all the time because their mothers usually can’t be at the bedside 24 hours a day. Also, while unborn children are insulated from many frequencies, premies are exposed to all the frequencies of the sounds in the nursery. She is interested in finding out how this added exposure, combined with the loss of the mother’s voice, might influence the premies’ development.


Writer: Aaron Hoover, 352-392-0186, ahoover@ufl.edu
Sources: Ken Gerhardt, 352-392-6622, gerhardt@csd.ufl.edu
Charlene Krueger, 352-273-6332, ckrueger@ufl.edu

Aaron Hoover | EurekAlert!
Further information:
http://www.ufl.edu/

More articles from Communications Media:

nachricht On patrol in social networks
25.01.2017 | Fraunhofer-Institut für Arbeitswirtschaft und Organisation IAO

nachricht Tile Based DASH Streaming for Virtual Reality with HEVC from Fraunhofer HHI
03.01.2017 | Fraunhofer-Institut für Nachrichtentechnik Heinrich-Hertz-Institut

All articles from Communications Media >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers use light to remotely control curvature of plastics

23.03.2017 | Power and Electrical Engineering

Sea ice extent sinks to record lows at both poles

23.03.2017 | Earth Sciences

Inactivate vaccines faster and more effectively using electron beams

23.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>