Nearly one-third of people will develop a voice disorder during their lifetime. These can range from fatigue or pain while speaking to losing their voice completely. The most common cause, making up 3 to 9 percent of cases, is vocal hyperfunction, a broad category that’s diagnosed only after more specific issues, such as cancer, are ruled out.
Some people develop nodules or polyps on their vocal folds, the bands of tissue in the larynx that vibrate to create voice. Others experience excessive tension, even without those growths, in the larynx, which alters their voice. Yet little is known about vocal hyperfunction (VH) and its causes or, in fact, whether it actually covers multiple conditions.
Without an obvious cause, these symptoms are sometimes attributed to psychology or the patient using their voice incorrectly. But Cara Stepp, a professor of speech, language, and hearing sciences and director of the STEPP Lab for Sensorimotor Rehabilitation Engineering, may have found a clue to another explanation. In a recent study, she established a connection between hearing problems and VH—“a paradigm shift for understanding development and treatment,” she and her colleagues wrote. Their findings are significant because there’s no auditory component to traditional voice therapy, and many people with VH relapse following therapy. Stepp believes the reason is an undiagnosed underlying issue, like a hearing impairment, hasn’t been addressed.
The current definition of VH is so broad, Stepp says, “there might be a few different disorders lurking in there.” With a new five-year grant, she’s focused on determining whether one or more of those unidentified disorders could be related to hearing impairment—and if so, whether that predicts which patients won’t benefit long-term from speech therapy.
ESTABLISHING AN AUDITORY-SPEECH CONNECTION
Stepp didn’t follow the traditional path into speech-language pathology. She studied engineering as an undergraduate and graduate student, focusing her research on hearing. As a doctoral student in biomedical engineering, she looked at how VH is assessed in clinics. Stepp noticed that the voices of the people she worked with—strained, high-effort, and “breathy”—matched descriptions of the voices of Deaf speakers.
“I got really interested in the way auditory feedback is used for speech,” she says. “For many years, it kept crossing my mind that maybe a subset of this big group of people [with VH] could have an auditory impairment.” After all, proper control of the larynx is related to a speaker’s ability to detect auditory cues from their own voice.
“THIS PROJECT STARTED WITH THEORETICAL SCIENCE. SEEING IT GET CLOSE TO BEING CLINICALLY ACTIONABLE MAKES ME EXCITED.”– Cara Stepp
In 2017, Stepp finally got the chance to investigate her theory. Working with the Massachusetts General Hospital Voice Center, Stepp and doctoral student Defne Abur (’22) recruited 124 people, half with vocal hyperfunction and half without. In one experiment, participants listened to recordings of their own voices. “What we found was that individuals with these voice disorders were less aware of auditory changes,” says Stepp.
In another exercise, participants were asked to repeat a sound several times. Researchers altered the pitch of their voices in real time and looped the audio through the participants’ headphones as they continued to speak. Members of the control group, those without VH, tended to adjust their voices in reaction. If they heard a higher-pitched voice than they expected, they compensated by speaking in a lower pitch.
Subjects with VH didn’t react as consistently, and some actually overcompensated—adjusting their voices several times more than that of the altered recording. Others “followed” their altered voice, speaking with a much higher pitch than the recording. “What was really interesting was that there was a relationship between the people who had these atypical integration behaviors and the people who had the worst auditory sensitivity to begin with,” Stepp says.
Those findings suggest a cause of VH that nobody had been looking for—impaired hearing translating into poor control of the larynx. “These are people who have been told, ‘You don’t have a neurological issue—you either have a structural issue, or what you have is related to behavior,’” Stepp says. “It makes it sound like it’s in your head.”
Stepp is now looking at whether hearing impairments are predictive of relapses following therapy. “We’re showing that there is a physiological reason” for some cases of VH, she says. And instead of people being left with the sense of having done something wrong to damage their voice, a more specific diagnosis and a more appropriate treatment plan could give them long-term relief.
FROM THEORY TO DISCOVERY
Allison Aaron, a speech-language pathologist who specializes in voice and a doctoral student in Stepp’s lab, is leading the data collection efforts on the new study. “There are a lot of unanswered questions about why someone might develop vocal hyperfunction,” says Aaron (’26). “Something that drove me into this field is the stigma surrounding voice injury.” It’s a stigma she has experienced.
During her senior year of high school, Aaron was playing a lead role in her school’s musical adaptation of Dirty Rotten Scoundrels and was singing a lot. Singing became harder and more uncomfortable, and eventually she was diagnosed with VH. For Aaron, the symptoms were manageable, and she still sings and performs today. But she wasn’t alone: In college, where she majored in vocal performance, Aaron met many other singers dealing with VH. In her work as a speech-language pathologist, she has treated many others with the condition. Some blame themselves for their injuries. “There are so many factors that might be driving vocal injury, and it’s not always about somebody’s technique,” she says. “It’s not that they’re a bad singer.”
In Stepp’s lab, Aaron uses the same tools as a music producer: headphones, microphones, and an effects processor to manipulate voices. Over the course of a session, she guides each study participant through a series of exercises aimed at better understanding the connection between hearing and speech. To test auditory perception, participants are asked to listen to sounds and determine when they’re higher or lower in pitch. Then, similar to Stepp’s last study, participants speak while listening to their voice through headphones. “By manipulating what they’re hearing, we can see how that changes the way they control their own voice,” Aaron says.
Data is gathered from each participant before and after speech therapy. Six months later, they’re surveyed on their voice-related quality of life to see if therapy had a lasting effect. Each session with a participant takes two to three hours, and requires sophisticated equipment—it’s not a process voice clinics could easily or affordably replicate. But Stepp and Aaron hope to develop a version of their protocol that clinicians could use, and even an online test for auditory acuity. If the measures they’re taking of study participants could become part of a typical voice clinic workup, Stepp says, “that could move this from a diagnosis of exclusion to something more specific.” Ultimately, the research could lead to a new diagnostic category and new therapies targeting auditory impairments.
“This project started with theoretical science. Seeing it get close to being clinically actionable makes me excited,” Stepp says. “I’m an engineer—we’re always excited when we think we can make things better.”