A study recently presented at the annual meeting of the Society for Neuroscience, is the first to match human behavior with left brain/right brain auditory processing tasks. Before this research, neuroimaging tests had hinted at differences in such processing.

“Language is processed mainly in the left hemisphere, and some have suggested that this is because the left hemisphere specializes in analyzing very rapidly changing sounds,” says the study’s senior investigator, Peter E. Turkeltaub, MD, PhD, a neurologist in the Center for Brain Plasticity and Recovery, a joint program ofGeorgetownUniversityand MedStar National Rehabilitation Network.

Turkeltaub and his team hid rapidly and slowly changing sounds in background noise and asked 24 volunteers to simply indicate whether they heard the sounds by pressing a button. “We asked the subjects to respond to sounds hidden in background noise,” Turkeltaub explained. “Each subject was told to use his or her right hand to respond during the first 20 sounds, then the left hand for the next 20, then right, then left, and so on.” He says when subjects used their right hand, they heard the rapidly changing sounds more often than when they used their left hands, and vice versa for the slowly changing sounds.

“Since the left hemisphere controls the right hand and vice versa, these results demonstrate that the two hemispheres specialize in different kinds of sounds: the left hemisphere likes rapidly changing sounds, such as consonants, and the right hemisphere likes slowly changing sounds, such as syllables or intonation,” Turkeltaub explains. The findings may eventually point to strategies to help stroke patients recover their language abilities, and to improve speech recognition in children with dyslexia.