A study from the University of British Columbia, Canada, found that babies’ use of teething toys consistently and effectively restrained tongue movement and as a result, their speech perception.

The development of language skills in a baby is believed to start when they are in gestation. By 27-29 weeks of gestational age, responses to auditory stimulation have been observed. Thus, when a baby is born, he or she has some “experience” discerning speech. Language acquisition in infancy is strongly based on speech perception. Identity with one’s native language is reported to begin in infancy as well.

The research on infant speech perception thus far has relied heavily on auditory and visual experiences. The article being discussed here suggests that one should include “oral motor” movements in infants in response to language cues as a way of speech perception as well.

For this study, the research team engaged 24 English-learning, six-month-old babies. The babies were tested for their ability to distinguish two different “d” sounds in their non-native language, Hindi (the two sounds require differential placement of tongue). Some experiments included teethers being placed in babies’ mouths to impede their free tongue movement, before being tested. Ultrasound studies were also conducted to understand the placement of the infants’ tongues with and without a teether.

The results from a series of experiments were:

• Six-month-old babies are capable of discerning the difference between two different “d” sounds in a non-native language.
• Placing a teether to obstruct free tongue movement resulted in the infants’ inability to differentiate the two sounds.
• Removing the teethers restored their ability to make the distinction.

Do the results imply that teethers impede speech development? Not so, according to the authors. They state, “The majority of infants experience sensorimotor disruptions fairly regularly, in the use of teething toys, soothers, or thumb- sucking behavior. We are not suggesting that these events would have long-term detrimental effects on language acquisition.” However, “This study indicates that the freedom to make small gestures with their tongue and other articulators when they listen to speech may be an important factor in babies’ perception of the sounds,” says the lead author, Dr. Werker, as quoted in the University of British Columbia News.

The findings strongly suggest that even before an infant is verbal, he or she develops language acquisition via speech discernment skills, based on not only auditory and visual but also sensorimotor (involving both sensory and movement functions) perceptions. This research could lead to a better understanding of conditions such as cleft palate, hearing impairment, and paralysis.

Written by Mangala Sarkar, Ph.D.