Researchers at Purdue University have developed a new technology that helps patients with Parkinson's disease overcome the tendency to speak too quietly by playing a recording of ambient sound that resembles the noisy chatter of a restaurant full of patrons.

"People with Parkinson's commonly have voice or speech problems that generally occur a little later in the disease," said Jessica Huber, PhD, CCC-SLP, an associate professor in the Department of Speech, Language & Hearing Sciences at Purdue.

Parkinson's is one of the most common degenerative neurological diseases, affecting 1.5 million people in the United States. Approximately 89 percent of patients have voice-related change, which is related to how loudly they speak; and about 45 percent have speech-related change, which is related to how clearly they speak.

"A major therapy is to get people to speak louder, which also may cause them to articulate more clearly," Dr. Huber said.

The most common therapy, the Lee Silverman Voice Treatment (LSVT®), trains patients to speak louder in one-hour sessions held four days a week for a month. "Some patients do great with this approach, but others do not," she stated. "They forget to keep speaking louder the minute they have left the therapy room."

LSVT tends to work less for people in the later stages of the disease or those who have some cognitive decline, she said. "I wanted to know whether there was an easier way to cue people during therapy, rather than telling them, 'Try to be twice as loud' or 'Try to focus on this sound meter and achieve this loudness.'"

Dr. Huber decided to take a new approach and ask patients to speak louder while a recording of background "multi-talker 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. But when I turned on the babble noise, they spoke over 10 dB louder."

The background sound elicits a well-known phenomenon called the Lombard effect, a reflex in which people automatically speak louder in the presence of background sound. "When you go into a loud room at a party, you talk louder without even realizing it," Dr. Huber said. "We've all had the experience where the room suddenly gets quiet and you're still shouting but you didn't know you were."

She created a new electronic technology using this principle. 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," she said. "We ask them to wear the system for about four hours a day as they go about their daily routine."

A critical part of the research is integrating the voice-detection sensor, which is called an accelerometer. The sensor was developed by students and faculty in the Weldon School of Biomedical Engineering at Purdue. "This sensor is crucial because it is essential that the background babble noise only turn on when the subject talks," Dr. Huber said.

The device prototype was built by engineering staff. An earlier prototype was built by Scott Kepner and Derek Tully, manager and assistant manager, respectively, of technical services for Speech, Language & Hearing Sciences.

Six patients wore the portable system for eight weeks. Data collected showed the system effectively prompts patients with Parkinson's to speak louder and more clearly.

"Their speech changes significantly," said Dr. Huber, who is working with doctoral student Meghan Darling. "There have been times where I called patients who had the device on, and I didn't recognize them."

She said the device also is beneficial because it trains people in their everyday environments: in their homes, with their spouses, in their churches, and in their social groups. The system works by measuring how much louder patients talk with and without the device after eight weeks of training.

The researchers are interested in examining the physiological changes elicited by the device. Patients wear a mask and sensors in elastic bands placed around the rib cage to record precise respiratory, laryngeal and articulatory data.

"We know the lung volume, and we know the pressure and the airflow they generate during speech," Dr. Huber said. "This tells us not only whether they are talking louder but how they are talking louder. For example, maybe they are using solely the respiratory system to get louder, or maybe it's all about the larynx."

They also plan to test how well the system works by having people who are not speech-language pathologists listen to the patients pronouncing words that could be easily confused with other words.

Future research will involve patients at the Rehabilitation Institute of Indianapolis. More study is needed to determine whether patients continue speaking louder when they are not wearing the device. The system could be developed further to use rechargeable batteries, Dr. Huber noted.

The research is funded by the National Institutes of Health. Purdue has filed a provisional patent on the concept.

The researchers are seeking patients with Parkinson's disease to participate in the study.

For More Information

• Jessica Huber, PhD, jhuber@purdue.edu

Emil Venere and Cynthia Sequin are on the Purdue News Service staff.