There are a number of theories of speech perception and word recognition, which have been proposed. One of these theories includes the motor theory of speech perception. This theory is based around the idea that we have a unique system for processing speech and our perception and production of speech are closely linked. The theory proposes that Motor commands in the brain, which control muscle movement, are also used to allow us to perceive speech. It relies on an underlying belief that humans are born with an innate speech-processing module, connecting words with mental commands.
New data supporting the Motor Theory of Speech Perception indicate that impediments to babies’ tongue movement may affect their ability to decipher speech sounds. Lead author Alison Bruderer, a postdoctoral fellow in the University of British Columbia’s School of Audiology and Speech Sciences, and her team placed teething toys in the mouths of 24 English-learning 6-month-old babies with English-speaking parents. The toys restricted the tongue tip’s movement, and the babies were unable to distinguish between two similar but distinct Hindi-language sounds. When the teethers were removed, allowing tongue movement, the infants could make the distinction.
Other theories of Speech perception focus on the coding of speech through auditory processing and learning within the brain. These theories use intermediate representations and an information-processing framework of speech. They state that perception is the result of a sequence of transformations. These theories have been the focus of a lot of research in the recent years.
Until now, research in speech-perception development and language acquisition has primarily used the auditory experience as the driving factor. Bruderer says.
Researchers should actually be looking at babies’ oral-motor movements as well.
The results of the research conducted at the University of British Columbia’s School of Audiology and Speech Sciences and published in Proceedings of the National Academy of Sciences do not however advocate for stopping the use of all teething toys, as there are still benefits in their use. However, the authors do recommend that babies be given plenty of time without the toys to allow them to move their tongues freely.