Bilinguals Juggle Sounds
New evidence suggests the experience of bilingualism changes how the nervous system responds to sound. A Northwestern University study provides biological evidence that bilinguals' rich experience with language "fine-tunes" their auditory nervous system and helps them juggle linguistic input in ways that enhance attention and working memory.
For the study, published in the April 30 issue of Proceedings of the National Academy of Sciences, the researchers recorded the brainstem responses to complex sounds (cABR) in 23 bilingual (English and Spanish) teenagers and 25 English-only-speaking teens as they heard speech sounds in two conditions.
In quiet conditions, the groups responded similarly. But against a backdrop of background noise, bilingual brains were significantly better at encoding the fundamental frequency of speech sounds known to underlie pitch perception and grouping of auditory objects. This enhancement was linked with advantages in auditory attention.
"Bilinguals are natural jugglers," said co-author and bilingualism expert Viorica Marian. "The bilingual juggles linguistic input and, it appears, automatically pays greater attention to relevant versus irrelevant sounds. Rather than promoting linguistic confusion, bilingualism promotes improved 'inhibitory control,' or the ability to pick out relevant speech sounds and ignore others." Search doi: 10.1073/pnas.1201575109.
Gesture Mismatch Equals Learning
In a discovery that could help instructors better teach children who are deaf, a team of University of Chicago researchers has found that children who produce gestures conveying different information from their sign language—gesture-sign mismatches—were more likely to succeed after instruction.
Through a series of experiments with 40 children, ages 9 to 12, all of whom were deaf and fluent in American Sign Language (ASL), researchers were able to distinguish ASL signs from gestures similar to those produced by hearing children when explaining the same math problems.
In the study, published on early view in the journal Cognition, researchers tested students' understanding of the equal (=) sign through a series of math problems. The researchers coded students' explanations and counted the number of times a child produced a gesture-sign mismatch.
Study results suggest that students who are deaf and who express ideas in gesture that are different from the ideas they express in sign may be more likely to learn to solve math problems.
Convenient Cochlear Implants
A University of Utah engineer and colleagues in Ohio have developed a tiny prototype microphone that can be implanted in the middle ear. The goal is to avoid problems—including issues of reliability, prevention of activities such as swimming, and social stigma—that arise when a microphone and related electronics are worn outside the head.
The proof-of-concept device has been tested successfully in the ear canals of four cadavers, the researchers report in a study published online in Transactions on Biomedical Engineering (April 30). To test the new microphone, the researchers used the temporal bones—bones at the side of the skull—and related ear canal, eardrum, and hearing bones from four cadaver donors.
Because the prototype—about the size of an eraser on a pencil—needs to be smaller and better at detecting quieter, low-pitched sounds, tests in people are about three years away. The study suggests incoming sound is transmitted most efficiently to the microphone if surgeons first remove the incus bone from the middle ear. U.S. Food and Drug Administration approval would be needed for an implant requiring such surgery.