Key Takeaways:
- Bioengineers at UCLA have invented a thin, flexible device that adheres to the neck and translates the muscle movements of the larynx into audible speech.
- The device is trained through machine learning to recognize which muscle movements correspond to which words.
- The self-powered technology could serve as a non-invasive tool for people who have lost the ability to speak due to vocal cord problems.
People with voice disorders, including those with pathological vocal cord conditions or who are recovering from laryngeal cancer surgeries, can often find it difficult or impossible to speak. That may soon change. A team of UCLA engineers has invented a soft, thin, stretchy device measuring just over 1 square inch that can be attached to the skin outside the throat to help people with dysfunctional vocal cords regain their voice function. Their advance was detailed March 12, 2024 in Nature Communications. The open-access article is titled “Speaking Without Vocal Folds Using a Machine-Learning-Assisted Wearable Sensing-Actuation System.”
The new bioelectric system, developed by Jun Chen, PhD, an Assistant Professor of Bioengineering at the UCLA Samueli School of Engineering, and his colleagues, is able to detect movement in a person’s larynx muscles and translate those signals into audible speech with the assistance of machine-learning technology — with nearly 95% accuracy.
The breakthrough is the latest in Chen’s efforts to help those with disabilities. His team previously developed a wearable glove capable of translating American Sign Language into English speech in real time to help users of ASL communicate with those who don’t know how to sign.
The wearable technology is designed to be flexible enough to move with and capture the activity of laryngeal muscles beneath the skin.
The tiny new patch-like device is made up of two components. One, a self-powered sensing component, detects and converts signals generated by muscle movements into high-fidelity, analyzable electrical signals; these electrical signals are then translated into speech signals using a machine-learning algorithm. The other, an actuation component, turns those speech signals into the desired voice expression.
The two components each contain two layers: a layer of biocompatible silicone compound polydimethylsiloxane, or PDMS, with elastic properties, and a magnetic induction layer made of copper induction coils. Sandwiched between the two components is a fifth layer containing PDMS mixed with micromagnets, which generates a magnetic field.
Utilizing a soft magnetoelastic sensing mechanism developed by Chen’s team in 2021, the device is capable of detecting changes in the magnetic field when it is altered as a result of mechanical forces — in this case, the movement of laryngeal muscles. The embedded serpentine induction coils in the magnetoelastic layers help generate high-fidelity electrical signals for sensing purposes.
Measuring 1.2 inches on each side, the device weighs about 7 grams and is just 0.06 inch thick. With double-sided biocompatible tape, it can easily adhere to an individual’s throat near the location of the vocal cords and can be reused by reapplying tape as needed.
Voice disorders are prevalent across all ages and demographic groups; research has shown that nearly 30% of people will experience at least one such disorder in their lifetime. Yet with therapeutic approaches, such as surgical interventions and voice therapy, voice recovery can stretch from three months to a year, with some invasive techniques requiring a significant period of mandatory postoperative voice rest.
“Existing solutions such as handheld electro-larynx devices and tracheoesophageal-puncture procedures can be inconvenient, invasive, or uncomfortable,” said Chen who leads the Wearable Bioelectronics Research Group at UCLA, and has been named one the world’s most highly cited researchers five years in a row. “This new device presents a wearable, non-invasive option capable of assisting patients in communicating during the period before treatment and during the post-treatment recovery period for voice disorders.”
This post is based on UCLA release written by Christine Wei-li Lee.