Laughter is often identified as good medicine. Dr. Caroline Menezes, though, sees it as a promising diagnostic tool for predicting the development of speech problems in children.The assistant professor of speech-language pathology in the Judith Herb College of Education, Health Science and Human Service is researching speech disorders: “It’s an umbrella term that covers many problems in childhood speech. All, though, are based in the sounds that make up language.”
Those language sounds are missing in many of the children receiving assistance in the college’s Speech-Language-Hearing Clinic. “We don’t really know the cause, though some of the disorders may be cognitive in origin,” Menezes said. “Perhaps we can better call this kind of disorder a phonological language delay, as the problem lies in a person’s inability to form appropriate linguistic concepts.”
Apraxia of speech is another disorder, in which a person has trouble saying what’s intended. In adults, Menezes explained, apraxia is often seen following a stroke: “It’s a breakdown in the brain’s programming of the sounds according to the linguistic rules. A person knows what a cat is, but they can’t string the sounds together to say the word, so they may say cap or fat.”
In that type of case, the person does have the appropriate linguistic concepts; the problem is articulating them. Similar symptoms may be observed in children, but a cause is often elusive. Thus the importance of understanding the factors that predispose children to develop speech disorders.
Menezes begins with the fact that humans possess an innate capacity to speak and communicate in language. “Language develops chronologically, ” she noted. “Some sounds are learned first, others later, with the most difficult ones coming last. If this system is delayed or disordered, it may manifest itself in what is generally known as phonological disorders.
“My idea is that because we use our vocal tract [that cavity in the head where sound is produced] for both laughter and speaking, maybe we can look at the way laughter develops in a child to predict whether the child is likely to develop a phonological and/or speech disorder.”
Laughter tends to develop at 4 months of age, speech at 20 months, with both affected by physical changes in the vocal tract as a child grows. In infants and young children, the tongue tends to lie forward in the mouth to facilitate suckling, and the vocal tract is relatively flat, creating a predisposition to certain sounds and patterns.
Some of the earliest and easiest speech patterns an infant makes are the consonant-vowel construct, Menezes said: “For example, baba. Papa. We see this pattern in the early babble stages, not only in English, but also in most spoken languages. This consonant-vowel linguistic structure is evident even at 4 months in the way we laugh: ha ha, hee hee.”
Chuckles, chortles and giggles don’t count; for her research, Menezes analyzes only spontaneous laughter blown out through the vocal tract: “You don’t have to know how to articulate with your tongue to laugh like that. It’s just dropping the jaw, which has the natural tendency to move the tongue back, so you get the H consonant sound that occurs in laughter.”
Comparing jaw and tongue movement in children’s laughter and that of adults, Menezes’ team looks for a regular pattern that might be superimposed on patterns of children thought to be predisposed to speech disorders, also helping to differentiate between phonological and articulation disorders. It may, she hopes, eventually allow speech-language professionals to identify such children for early intervention.
The research — heavy on data mining and analysis — is in its early stages and represents a very new field, she added. “Only a few scientists in the world are looking at laughter in this way.”