Northwestern University researchers have developed the first smart wearable device to continuously track how much people use their voices, alerting them to overuse before vocal fatigue and potential injury set in.
The first-of-its-kind, battery-powered, wireless device and accompanying algorithms could be a game-changer for professional singers, teachers, politicians, call-center workers, coaches and anyone who relies on their voices to communicate effectively and make a living. It also could help clinicians remotely and continuously monitor patients with voice disorders throughout their treatment.
Developed by an interdisciplinary team of materials scientists, biomedical engineers, opera singers and a speech-language pathologist, the research behind the new technology will be published during the week of Feb. 20 in the Proceedings of the National Academy of Sciences.
The soft, flexible, postage-stamp-sized device comfortably adheres to the upper chest to sense the subtle vibrations associated with talking and singing. From there, the captured data is instantaneously streamed via Bluetooth to the users’ smartphone or tablet, so they can monitor their vocal activities in real time throughout the day and measure cumulative total vocal usage. Custom machine-learning algorithms distinguish the difference between speaking and singing, enabling singers to separately track each activity.
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With the app, users can set their personalized vocal thresholds. When they near that threshold, their smartphone, smartwatch or an accompanying device located on the wrist provides real-time haptic feedback as an alert. Then, they can rest their voices before pushing it too far.
“The device precisely measures the amplitude and frequency for speaking and singing,” said Northwestern’s John A. Rogers, a bioelectronics pioneer who led the device’s development. “Those two parameters are most important in determining the overall load that’s occurring on the vocal folds. Being aware of those parameters, both at a given instant and cumulatively over time, is essential for managing healthy patterns of vocalization.”
“It’s easy for people to forget how much they use their voice,” said Northwestern’s Theresa Brancaccio, a voice expert who co-led the study. “Seasoned classical singers tend to be more aware of their vocal usage because they have lived and learned. But some people — especially singers with less training or people, like teachers, politicians and sports coaches, who must speak a lot for their jobs — often don’t realize how much they are pushing it. We want to give them greater awareness to help prevent injury.”
Rogers is the Louis Simpson and Kimberly Querrey Professor of Materials Science and Engineering, Biomedical Engineering and Neurological Surgery in the McCormick School of Engineering and Northwestern University Feinberg School of Medicine. He also is director of the Querrey Simpson Institute for Bioelectronics. A distinguished operatic performer, mezzo-soprano, Brancaccio is a senior lecturer at Northwestern’s Bienen School of Music, where she teaches voice and vocal pedagogy.
Unaware of overuse
For the millions of people in the U.S. who make their livings by speaking or singing, vocal fatigue is a constant, looming threat. The common condition occurs when overused vocal folds swell, making the voice sound raspy and lose endurance. Vocal fatigue negatively affects singers, in particular, altering their abilities to sing clearly or hit the same notes as their healthy voice can. At best, one short period of vocal fatigue can briefly interrupt a singer’s plans. At worst, it can lead to enough damage to derail a career.
Lack of awareness is the underlying problem. People rarely make the connection between vocal activities and how those activities affect their voices. Although one in 13 U.S. adults have experienced vocal fatigue, most people don’t notice they are overusing their voices until hoarseness already has set in.
“What leads people into trouble is when events stack up,” Brancaccio said. “They might have rehearsals, teach lessons, talk during class discussions and then go to a loud party, where they have to yell over the background noise. Then, throw a cold or illness into the mix. People have no idea how much they are coughing or clearing their throats. When these events stack up for days, that can put major stress on the voice.”