Corvin has involuntary movements related to cerebral palsy that make using a mouse impossible. He tried finger and eyebrow switches but couldn’t control them consistently. An off-the-shelf, microphone-based sound switch misfired in noisy environments and exhausted him because it only responded to loud vocalizations.
Then Corvin tried the Hummer – a novel switch developed at Bloorview that detects vocal-chord vibrations when a child makes a sound or hums a tune and turns them into computer functions. “It was the first switch he could easily access,” says his mom Varinia.
Wearing a lightweight neckband, Corvin demonstrated the switch while using a story-making software. The program scanned different storylines related to a princess on an adventure. Corvin clicked his choices by making a sound such as “uh” or “oh” when they appeared on the screen – and showed his pleasure with an awesome smile.
“Certain sounds we make and hums cause the vocal chords to vibrate in a pattern that recurs at regular intervals,” says Tiago Falk, a postdoctoral researcher in biomedical engineering at Bloorview and the primary inventor (in photo above).
A sensor the size of a nickel embedded in the neckband sends signals to a microcontroller that detects the pattern and activates a mouse function – such as turning a page in an online book, clicking an icon on the screen, or moving the mouse left or right.
The Hummer is perfect for children who don’t speak and have physical disabilities that make conventional switches challenging.
A big advantage is that the sensor doesn’t respond to background noises, coughs or other user-generated noises – which can cause false responses in microphone sound switches like the one Corvin initially tried.
Vibrations are produced naturally during voiced speech or hums – no matter how loudly or softly the child vocalizes – so even quiet sounds or silent hums activate the Hummer. In contrast, microphone switches can fatigue users because they require speech of a certain volume.
The current Hummer is a single switch operating one computer function.
A new version is in the works that will allow users to activate a variety of functions based on differences in the pitch and duration of what they say and hum. For example, a quick, low hum might move the cursor right, whereas a slow, high-pitched word would translate into a click.
In future, the system could be used to control voice technology and electronic devices like a TV and lights and to drive a power wheelchair.
“In the short term, it allows Corvin to do school activities like reading and journal writing,” Varinia says. “And in the long-term, it opens the door to a communication device and to accessing environmental controls so he can be more independent.”