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Smartphone App Advances Diagnosis of Voice Disorders

Adele’s recent triumphant return to sing at the Grammy Awards after recuperating from vocal fold surgery is a highlight of what can now be safely accomplished with state-of-the-art laryngeal surgical techniques. This success story stands in stark contrast to Julie Andrews’ experience a decade ago. Ms. Andrews lost her singing voice due to a much less advanced surgical procedure. The availability of new surgical techniques is removing the fear among singers that they risk the chance of losing their voice by trying to get it back.

Robert Hillman, Ph.D

Robert Hillman, Ph.D.

But as much as the surgical state of the art has advanced, the way doctors try to determine what causes some people to develop voice disorders is still decidedly low-tech. “We ask people how they use their voices,” says speech-language pathologist Robert Hillman, Ph.D. (who is a Harvard Medical School colleague of Steven Zeitel, M.D., Adele’s surgeon), “but the problem is, people are really bad historians when it comes to voice use. We have data that shows people tend to be off on average 150 to 200 percent when simply trying to estimate how much they use their voices during a typical day.”

Finding a way to monitor voice use as people go about their normal day-to-day activities is something that Dr. Hillman, who is also research director of the Center for Laryngeal Surgery and Voice Rehabilitation at Massachusetts General Hospital, has been working on with funding from the NIDCD. He and his team have developed a mobile monitoring device that relies on smartphone technology to gather a week’s worth of talking, singing, yelling—whatever it is people do with their voices.

The sound of our voice is produced by vibration of the vocal folds, which are two bands of multilayered tissue positioned opposite each other in the larynx. When we’re not speaking, the vocal folds are open so that we can breathe, but when it’s time to speak the vocal folds snap together. These vibrations form the basis for our voices. Overusing or straining the voice (to reach higher notes or louder volume) can cause people who use their voice in their jobs—such as singers, but also teachers, salespeople, lawyers, even ministers and other clergy—to damage their vocal folds and cause hoarseness. Sometimes the damage takes the form of vocal nodules or polyps, which are caused by repeated damage to vocal fold tissue, much like a blister or callus forms on a finger or toe.

Although surgery may be necessary for some kinds of vocal fold damage, other people may only need to retrain their vocal habits. In either situation, their speech-language pathologist needs to understand what caused the damage in the first place, and then find ways to keep them from making the same behavioral mistakes again. This is where a mobile monitoring device comes in handy, both in helping to evaluate a problem for accurate diagnosis, and afterwards to aid in rehabilitation.

The device that Dr. Hillman and his team have developed uses a small receiver the size of a dime (called an accelerometer), attached with double-sided sticky tape to the base of the throat, which captures the vibrations that are transmitted from the larynx through the skin. “The goal is to make it as unobtrusive as possible,” says Dr. Hillman, “because you want people to be doing things the way they normally do them. The impact has to be minimal.” In fact, an earlier version of the device was so unobtrusive that Steven Tyler wore it during an Aerosmith concert to document the vocal extremes of rock-and-roll singing.

A wire from the accelerometer is plugged into the microphone input of an Android smartphone, which can be worn in a holster or popped into a pocket. The phone’s battery powers the accelerometer and a special software program, an “app,” collects the data. It can hold up to seven, 18-hour days of recording.

Once the data are downloaded, a custom-designed software program analyzes the strength and frequency of the vibrations to produce a graph that shows daily voice usage in terms of amount, volume, and pitch.

One of the goals of the monitoring device is to be able to use the data to begin to make some correlations between patterns of voice use and the risk for a vocal disorder. What is normal and what is abnormal voice use? Are there certain ways of using the voice that can cause particular problems? A future feature, when the device goes into clinical testing, will be the addition of a feedback method, such as a buzzer or vibration, to tell the wearer when he is using his voice incorrectly.

“Voice therapy is like any kind of behavior change therapy,” says Dr. Hillman. “People will do what we tell them to do when they’re in front of us, but maybe not when they’re not being watched. Highly habituated vocal habits are hard to break.” The feedback device could act like a virtual speech-language pathologist, reminding the patient when she falls back on old habits and giving her a gentle nudge to try on the new ones.

The next step in this line of NIDCD-funded research is a large-scale data collection effort in as many as 400 subjects, both with and without voice-use-related disorders, to further fine-tune the device’s diagnostic abilities and establish the best measures to use for clinical assessment and biofeedback.

Dr. Hillman and his colleagues are eager for the results, which will hopefully bring a mobile voice-monitoring device that much closer to being the standard of care—much like the Holter monitor is for heart disease—for the diagnosis and treatment of voice disorders.