Cambridge researchers develop device to help stroke patients regain natural speech
The Revoice device uses AI to expand silently mouthed words into fluent sentences.
A new wearable device called Revoice could pave the way for stroke patients with speech impairments to regain natural and fluent communication.
Developed by researchers at the University of Cambridge, Revoice is a soft, flexible, and washable choker that uses ultra-sensitive sensors and artificial intelligence to decode speech signals and emotional cues.
The technology is designed to help people with dysarthria – a common post-stroke speech impairment – express themselves without invasive procedures like brain implants.
Revoice picks up tiny vibrations from throat muscles and heart rate, which are processed by AI agents. One agent reconstructs silently mouthed words into speech, while another interprets emotional states and contextual information, such as time or weather, to transform short phrases into full sentences.
For simplicity and functionality, the device uses a lightweight large language model (LLM) to expand sentences in real time and runs on minimal power.
In a trial involving five patients with dysarthria and ten healthy participants, the device achieved a word error rate of 4.2% and a sentence error rate of 2.9%.
By nodding twice, users could also select expanded sentences crafted by the AI – for example, the phrase “We go hospital” was transformed into “Even though it’s getting a bit late, I’m still feeling uncomfortable. Can we go to the hospital now?”
Professor Luigi Occhipinti, who led the research, described the frustration faced by stroke patients with dysarthria:
“When people have dysarthria following a stroke, they know exactly what they want to say, but physically struggle to say it. That frustration can be profound, not just for the patients, but for their families.”
Participants from the trial reported a 55% increase in satisfaction using the device. The researchers hope future versions will include multilingual features, expanded emotional recognition, and standalone functionality for everyday use.
Occhipinti said the goal of Revoice is to restore independence, adding:
“Communication is fundamental to dignity and recovery.”
The research is supported by the British Council, Haleon, and the Engineering and Physical Sciences Research Council (EPSRC).
Extensive clinical trials are required before the device can be widely available, but the team plans to launch a Cambridge-based study for native English-speaking dysarthria patients later this year.