Study revealing brain activity patterns underlying fluent speech was published on June 1, 2018.
This study was conducted by the researchers at the University of California – San Francisco. The new research revealed that the speech centers of brain is organized more according to the physical needs of the vocal tract. However, in reality, mouth forms the sound differently in these two words to prepare for the different vowels that follow and this physical distinction now appears to be more important to the brain regions responsible for producing speech than the theoretical sameness of the phoneme.
The findings of this study is an extension of the previous studies and this could help in the development of new generation of prosthetic devices for those who are unable to speak: brain implants could monitor neural activity related to speech production and rapidly and directly translate those signals into synthetic spoken language.
Since the research team was not able to simultaneously record the neural activity, tongue, mouth and larynx movements of the volunteers, only audio of the volunteers speaking was recorded. Then, a new deep learning algorithm was developed for the estimation regarding which movements were made during specific speaking tasks. This method allowed the researchers to identify distinct populations of neurons responsible for the specific vocal tract movement patterns needed to produce fluent speech sounds, a level of complexity that had not been seen in previous experiments that used simpler syllable-by-syllable speech tasks. Josh Chartier, one of the researchers said, “This study highlights why we need to take into account vocal tract movements and not just linguistic features like phonemes when studying speech production.”