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 suggests that the differences start at the ear.
"We always assumed that our left and right ears worked exactly the same way," said lead researcher Yvonne Sininger of the University of California at Los Angeles.
"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," she said.
The discovery, described in the current issue of Science Magazine, will help doctors enhance speech and language development in hearing-impaired newborns and the rehabilitation of persons with hearing loss.
Sininger and her colleagues studied hearing in more than 3,000 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.