Unlocking How Our Brain Controls The Musicality Of Speech
When we speak, the inflection in our voices makes a difference. The way we change our pitch can indicate whether a sentence is a question or a statement (“She sings.” vs. “She sings?”), convey mood, and give additional emphasis to certain words.
We control the pitch of our speech with the vocal folds of our larynx—our “voice box”. A new study from NYSCF – Robertson Neuroscience Investigator and Professor of Neurological Surgery at the University of California, San Francisco Edward Chang, MD, reveals which part of the brain controls our voice box. This knowledge could inform the creation of prosthetic devices that allow people who cannot speak to express themselves through naturalistic synthetic voices.
To examine which area of the brain is responsible for the musicality of our speech, the researchers used a technique called electrocorticography (ECoG). In ECoG, a group of electrodes is positioned over the brain, allowing researchers to locate and track neuronal activity.
A group of subjects fitted with these electrodes was asked to read a series of sentences, each time emphasizing a different word in a sentence (i.e. “I never said she stole my money” and “I never said she stole my money”). This allowed the researchers to look at differences in neural activity as the subjects changed the inflection in their voices without changing the words they were saying.
The team found that when subjects had a quick change in the pitch of their speech, an area of their brain called the dorsal laryngeal motor cortex became more active. This region also became more active when a subject heightened the pitch of their voice on an individual word. When this area was electrically stimulated, the subjects’ larynx muscles flexed, and some subjects made vocalizations. The team also found increased activity in the dorsal laryngeal motor cortex as the subjects listened to their own speech played back.
What can we do with this information? Dr. Chang’s lab is now investigating whether we can predict which word will be emphasized in a sentence by simply examining someone’s brain activity. In the future, the lab hopes to use their findings to develop a prosthetic that could mimic the natural musicality of our speech by reading electrical activity in our brains.