PROVO — When people make the sounds f, v or th, others can see their tongues moving at the front of the mouths.
By when they make vowel sounds, it's more difficult to see how and where the tongue hits the palate.
Placement of the tongue is crucial in learning how to speak. And a person who is deaf or suffers from a stroke or speech impediment must train the tongue about placement against the palate.
Thomas Fletcher has spent more than 30 years in an almost five-decade career developing the palatometer — a device that measures where the tongue hits the palate — and he believes it can help deaf people, stroke patients and people with speech impediments learn to speak more clearly.
The device has three components: a mouth piece speckled with 118 tiny gold sensors that resembles an orthodontic retainer, an interface worn around the neck that connects to a computer, and computer software that shows a simulated tongue enabling patients to see where their tongue is hitting the palate in real time.
"Getting the tongue in the right place is so hard if you're deaf or had a stroke," said Fletcher, who is semiretired and does research part time for Brigham Young University's audiology and speech-language pathology department. "Once it feels right (inside the mouth), it'll sound right."
"Now we're really giving them a visual sign," said Christopher Dromey, a professor in the department at BYU who has conducted research with Fletcher.
The palatometer is used during speech therapy. Both the speech-language pathologist and person learning to speak place a "pseudo-palate" piece inside their mouths and wear the interfaces to practice speaking.
The computer software shows pictures of two simulated mouths.
As the speech therapist pronounces a sound, the tongue touches specific sensors — for instance, when making the s sound, the tongue touches sensors in the front of the mouth near the upper front teeth; the sh sound is a little farther back in the mouth, and the b and p sounds are made when the lips smack together.
When tongue or lips touch the sensors, blue dots light up on the simulated mouth that correspond to the sensors in the speech-language pathologist's mouth.
After the speech-language pathologist pronounces the sound, the person learning to speak tries to imitate, positioning and repositioning the tongue and lips using the simulated mouth as a guide.
The speech-language pathologist's work can be saved on the software, and the person learning to speak can take it home for practice. The time needed for people to learn to speak depends on their commitment to practicing and other factors such as age and whether they can hear or are correcting a minor speech impediment, Fletcher said.
Fletcher has developed numerous palatometers throughout the years, with the help of other speech-language researchers, engineers, medical physicists and computer programers at Utah State University, the University of New Mexico, the University of Alabama and BYU.
The most recent palatometer was fine-tuned about five years ago, and a patent is pending. It costs between $200 and $300.
Fletcher said he wants speech-language pathologists everywhere to be able to obtain palatometers and provide instructions through his company, LogoMetrix.
"There are probably around 18 to 20 universities that have bought them," he said.
Fletcher began working on the palatometer after seeing an article in a academic journal in 1969. Researchers at the University of Washington watched people speak while the subjects wore dentures with silver sensors attached.
"I called them," Fletcher said. "We were working with deaf kids. I asked, 'What are you doing with the study?' They said, 'Nothing.' "
The researchers were excited for Fletcher to continue their work. Saliva corrodes silver within seconds, which led Fletcher to use gold. He substituted pseudo-palatometers for the dentures. Over the years, he found plastics that were less bulky than his original palatometer, which cost about $1,500, he said.
While the palatometer can teach speech, vocal tone and inflection must be learned through other methods, Dromey said.