Unlocking the voice in every child
Madison, WI – With her innovative research, Houri K.Vorperian links childcare and science, striving to give a voice to children who have little.
Vorperian journeys from the clinic to the lab, accumulating 15 years worth of award-winning biological research on vocal tract development and speech production in children with Down Syndrome.
After receiving her Masters in Speech Pathology, Vorperian, with the Vocal Tract Development Lab at the Waisman Center, practiced clinically, helping young children with speech disorders discover their own voice.
“I used to work with children who couldn’t speak at all. Many of them used augmented devices to create words and sentences. But, when these devices have robotic voices, how do we expect these children to communicate effectively with their peers?”
Observing the tone of these augmented, or computer-generated devices, as a barrier to her patients’ progress, Vorperian began programming intonation to add personality to the speaker’s words.
Learning about the science behind speech production soon became necessary to advance the programming. For Vorperian, acquiring that information was truly like finding a lost ship at sea.
“I felt very frustrated with how little research was out there regarding speech science. However, it was more frustrating that there wasn’t a venue in place where I could discuss discoveries and questions with my colleagues.”
Why didn’t this technique work? What is the science behind how this happened? After receiving her doctorate, she reached out to the Waisman Center in hopes of answering these questions.
In 2000, Waisman agreed to host the Vocal Tract Development Lab (VT Lab). Today, the VT Lab is home to the largest collection of data compared to any other UW Lab. Additionally, the Journal of Speech, Language and Hearing Research 2010 Editor’s Award went to the VT Lab for their study on developmental sexual dimorphism, or the physical developmental differences between males and females.
Vorperian uses a combination of tools to evaluate her research: imaging (comparing MRI and CAT scan images), acoustics (recordings of children’s speech) and vocal tract modeling (3D rendering of various vocal tracts).
By using a variety of tools, Vorperian hopes to understand how the vocal tract anatomy changes over a lifetime between those with or without Down Syndrome.
Vorperian explains that in order to understand her work, one must first understand basic acoustic theory, or in this case, how children produce vocal sound.
The vocal tract is a set of three cavities, or spaces – oral, pharyngeal, and nasal – all of which are involved in the formation of speech, or vocal sounds. Each of these cavities is formed by a combination of structures that are either soft (such as the tongue, soft palate and lips) or hard (jaw and hard palate).
When your vocal folds vibrate, these cavities act as a resonator to trap those vibrations and emit them as sound waves. The problem occurs when vocal tract length increases, these resonators decrease in size causing the sound to distort. This can affect resonance; the tone, pitch and clarity of speech.
“Think of a piccolo as a child’s vocal tract. A piccolo is short and high-pitched. If you take a piccolo and stretch it to the length of an oboe it distorts the sound,” Vorperian says.
Many issues children have with speech are linked to the anatomical, or biological structure of these cavities, and how much space children have to create sound.
Imagine glass bottles filled with different levels of water. When you blow into each bottle they each have a different pitch, or resonant frequency. This is due to how much space is leftover for the sound waves to reflect off the glass. Like the glass bottles, each vowel sound has its own resonant frequency.
A typically developing child will have a wide array of bottles with distinctly different levels of water; therefore, various resonant frequencies. This means a typically developing child has the ability to clearly pronounce words that utilize many different vowels.
For a child with Down syndrome, all their bottles have around the same amount of water and therefore, unvarying resonant frequencies. This means a child with Down syndrome cannot clearly pronounce words that utilize different vowels – a condition that minimally changes during their lifetime and permanently inhibits speech.
A condition, according to the National Down Syndrome Society (NDSS), that affects the 6000 children born every year with Down Syndrome. Without speech, those with Down Syndrome could struggle making friends, getting a job or finding love.
To prevent this from happening, Vorperian has identified the four main syllable sounds the vocal cavity can create: /a/ as in apple, /ae/ as in egg, /i/ as in ill, and /u/ as in umbrella.
When each of these is pronounced, the tongue moves to a different place in the mouth. Pegged “the vowel quadrilateral” the different vowel sounds are produced in 4 corners of your mouth: /i/ top front, /u/ top back, /ae/ bottom front, /a/ bottom back.
To test this “glass bottle theory” the VT Lab measured the anatomical speech response of typically developing children to those with Down Syndrome to see who could speak these vowels clearly.
Using a set of 22 words that incorporate the four extreme vowels, researchers prompted children to repeat the word or identify the word from a picture.
Using software, the children were prompted to speak the words aloud. Recordings were obtained from 53 individuals with Down Syndrome between ages 4 to 36 and from typically developing children ages 4 to 5. 25 adult listeners heard and transcribed the Down Syndrome recordings and 10 adult listeners transcribed the typically developing. To reduce bias, each recording was transcribed by 5 different listeners.
The results are profound: Typically developing children are understood by adults 80-100% of the time, meaning that nearly every adult received the message this child was trying to transmit. Whereas in Down Syndrome children, who have smaller acoustic space, were understood by adults a little over half the time (60%).
With an upwards of 400,000 Americans with Down Syndrome today (NDSS), it’s important we do our best to create tools that make things easier for patients and their families.
“Speech therapists can use my information to develop targeted treatment for Down Syndrome children. This can help improve speech intelligibility and overall reception of children with Down Syndrome,” Vorperian says.
No matter how difficult the road may be ahead, Vorperian has devoted her life to research, determined to make sure every child’s voice is heard.
