Researchers discover part of brain accountable for speech processing

A new study has revealed that the region of the brain that is sensitive to the timing of speech plays a vital role in human language.

Brain needs to interpret different time signatures in order to understand what others are saying. Therefore, timing plays an important part for human speech. Speech is generally made of different time measurements.

Phonemes are the shortest unit of speech, which lasts between 30 to 60 milliseconds. The other measurement is syllable, which lasts for between 200 and 300 milliseconds and whole words are even longer.

In order to deal with this information, information in chunks is sampled by the auditory system. The information is equivalent to average consonant or syllable.

A research team led by Tobias Overath, an assistant research professor of psychology and neuroscience at Duke, tried to do the same. The team cut recordings of foreign speech in chunks ranging between 30 and 660 milliseconds in length. They used a new algorithm that creates speech quilts to reassemble chucks.

It was found that the shorter the speech was, the greater the disruption was in the speech's original structure. Afterwards, the researchers played the speech quilts to the participants as the same time they were undergoing brain scans.

They found that when the 480 and 960 milliseconds quilts were played, superior temporal sulcus or STS was the region of the brain which became highly active. However, they also noticed that the brain region was not active during the 30 millisecond quilt.

This was the first time STS, which works to integrate auditory and other sensory information showed to respond to time structures in speech.

The researchers have tested other control sounds that imitated speech to back up their findings. After arranging the control stimuli into quilts, it was played to participants. They noted that the brain region did not respond to the control quilts.