[h2]Speak to my right ear, sing to my left[/h2] [div class="author"]Agençe France-Presse[/div]
[div class="date"]Monday, 13 September 2004
[/div] [table class="photo" align="right" border="0" cellpadding="5" cellspacing="0" width="1%"] [tbody][tr valign="top"] [td align="left"][img]http://www.abc.net.au/science/news/img/health/earphone130904.jpg" alt="Listening" title="Listening" border="0"][/td] [/tr] [tr valign="top"] [td align="left"] [div class="caption"]Which ear do you use? (Image: iStockphoto)[/div] [/td] [/tr] [/tbody][/table] [div class="story"] Our left and right ears process sound differently, according to new research.
When scientists studied babies' hearing they found the left ear was more attuned to music and the right better at picking up speech-like sounds.
Lead researcher Dr Yvonne Sininger of the [a href="http://www.ucla.edu/" target="_blank"]University of California[/a] at Los Angeles and team published their study in the latest issue of the journal [a href="http://www.sciencemag.org/" target="_blank"]Science[/a].
It has long been known that the right and left halves of the brain process sound differently, but those differences were thought to stem from cellular properties unique to each brain hemisphere.
The new research suggested the differences start at the ear.
"We always assumed that our left and right ears worked exactly the same way," said Sininger.
"As a result, we tended to think it didn't matter which ear was impaired in a person. Now we see that it may have profound implications for the individual's speech and language development."
The researchers said the discovery will help doctors enhance speech and language development in hearing-impaired newborns and the rehabilitation of people with hearing loss.
Sininger and her colleagues studied hearing in more than 3000 newborns, specifically tiny amplifiers located in the outer hair cells of the inner ear.
These cells contract and expand to amplify sound vibrations, convert the vibrations to neural cells and send them to the brain.
The scientists inserted tiny probes into the babies' ears that emitted two different types of sounds and measured the amplified vibrations.
They found that speech-like clicks triggered greater amplification in the right ear, while music-like sustained tones were more greatly amplified by the left ear.
"We were intrigued to discover that the clicks triggered more amplification in the baby's right ear, while the tones induced more amplification in the baby's left ear," Sininger said.
"This parallels how the brain processes speech and music, except the sides are reversed due to the brain's cross connections.
"Our findings demonstrate that auditory processing starts in the ear before it is ever seen in the brain," said co-author Associate Professor Barbara Cone-Wesson of the [a href="http://www.arizona.edu/" target="_blank"]University of Arizona[/a]. "Even at birth, the ear is structured to distinguish between different types of sound and to send it to the right place in the brain." [/div]
