Research Communications

Listen Up 

Jeff DiGiovanni studies how to improve hearing aid technologies

May 17, 2010

Most people associate hearing loss with an inability to hear soft sounds. But the condition also can create distortion, which makes it tough for someone to understand the difference between tones such as “a” or “e.” Those with hearing loss struggle to understand group discussions or conversations in a crowd, as they can’t pick out a voice from background noises.

Ohio University researcher Jeff DiGiovanni has been working to overcome these problems and improve hearing aid technology by testing two audiology theories in his lab.

Jeff DiGiovanni

One theory, called “spectral enhancement,” hadn’t been tested until DiGiovanni took a look. Spectral enhancement makes vowel sounds and certain consonants—often difficult to understand through distortion—more distinct.

“Spectral enhancement picks out prominent sounds in a very complex sound,” explains DiGiovanni, an associate professor of hearing, speech, and language sciences.

After validating the theory, DiGiovanni suggested ways in which hearing aid manufacturers could best use this algorithm to enhance their products.
DiGiovanni and his colleagues also have been exploring a concept called “clear speech,” the slow, deliberate enunciation of words. People often use clear speech when they talk to those who seem hard of hearing or who are not native English speakers.

“Everyone actually does this the same way, and they are a lot more intelligible, about 25 percent more so,” he says. “To me that was pretty striking, so we reviewed existing literature and developed a way to convert normally spoken speech to ‘clear speech.’”

DiGiovanni’s lab tested two qualities of clear speech, increased consonant duration and consonant amplification—which amounts to slower and louder enunciation. They tested two groups of people, one that had hearing loss and one without. DiGiovanni found that clear speech improves speech understanding for both groups. However, there is a point at which too much consonant duration and consonant amplification negatively affects hearing. 

By isolating the differences between clear speech and normal conversational speech, DiGiovanni hopes to create better technology.

“The number one goal is to innovate algorithms for hearing aids to manipulate sound to make speech more understandable, even when there is distortion in the ear,” he says.

In addition to his lab work, in February DiGiovanni published a second edition of The Hearing Aid Handbook. The guide, aimed at audiologists, hearing professionals, professors, and audiology students, includes profiles of hearing-aid manufacturers, specifications, and features about hearing aids currently on the market. He calls it the equivalent to the Physicians’ Desk Reference. The researcher hopes to someday write a manual for consumers to help them educate people on how to maneuver the process of purchasing a hearing aid.

“There is a huge disconnect between what information is available,” he says, “and the consumer’s access to it.”

By Meghan Holohan

This story will appear in the Spring/Summer 2010 issue of Perspectives magazine.