"People with Parkinson's disease commonly have voice and speech problems," said Jessica Huber, an associate professor in Purdue's Department of Speech, Language and Hearing Sciences.
"At some point in their disease they will have some form of voice or speech disorder that generally occurs a little later in the disease," she added.
The most common therapy, the Lee Silverman voice treatment program, trains patients to speak louder in one-hour sessions four days a week for a month.
"Some Parkinson's patients do great with this approach, but others do not. They forget to keep speaking louder the minute they have left the therapy room," said Huber.
Lee Silverman tends to work less for people with later stages of disease or those who have some cognitive decline.
Huber used a new approach: The patients were asked to speak louder while a recording of background "multitalker babble noise" was played. The noise is essentially the sound of a restaurant full of patrons, but without the clattering silverware and clinking glasses.
"They had an easier time getting louder when I had the noise in the room," she said.
"Ordinarily, when I asked them to be twice as loud they would say they couldn't. They couldn't speak 10 decibels louder, but when I turned on the babble noise, they spoke over 10 decibels louder," she added.
In the device built by engineering resources manager Jim Jones and senior research engineer Kirk Foster, both in the Weldon School, the voice-activated device automatically plays the background babble when the person begins to speak.
A sensor placed on the neck detects that the person has begun to speak and tells the device to play the babble through an earpiece worn by the patient.
"I got the idea that if we train them with a natural cue in their everyday environment, we will probably get better results. We ask them to wear the system for about four hours a day as they go about their daily routine," she added.