By Kelly Bradburn
Staff Writer

With summer approaching, many students are looking forward to going to concerts and bumping the latest CD in their car stereos. These activities could, however, be doing more damage to their ears than to their bank accounts.

Amy Neel, Purdue assistant professor of audio and speech sciences, is studying the effects of age and noise-related hearing loss, as well as hearing aid use, on speech perception. The research could possibly lead to the development of training techniques that would be used to enhance speech perception for hearing aid users.

"We’re focusing on people who experience hearing loss related to aging and noise exposure, but we’re anticipating, in the next several years, that younger and younger people are going to have more hearing loss because of the way society is with noise," said Neel.

While most hearing loss is due to prolonged exposure to noise, Neel is specifically interested in studying the effects of impaired hearing and speech perception on older people. Most of her participants have been between 70 and 80 years old.

The first part of Neel’s research will focus on people who have worn hearing aids for a long period of time. While the second part will test new users before and after receiving their hearing aids, as well as several weeks after. Once the difficult sounds are determined, Neel hopes to develop an interactive computer technique that would provide training for hearing loss individuals.

Neel is seeking participants who have sloping, high frequency hearing loss related to age or noise exposure. Volunteers should be native speakers of American English. There will be one to three sessions, approximately 60 to 90 minutes each, where volunteers will participate with and without their hearing aids. The participants will also receive free parking on campus and $10 per hour for their time.

According to Neel, several factors, such as head trauma or tumors, can cause hearing loss; however, the most common factor is noise exposure. While younger people may not notice the loss immediately, years of loud noise exposure can lead to hearing loss when they’re older.

"If you’ve ever gone to a concert and you come out and everything sounds muffled, you’ve actually probably caused some damage to your hair cells [in the inner ear]," said Neel. "It will gradually come back; we call that a temporary threshold shift. But, if the noise is loud enough and prolonged enough, it can cause permanent damage, and it’s not going to come back."

With typical hearing loss, due to age or noise, some sounds are more difficult to understand than others due to the frequency components of those sounds. High frequency sounds include such sounds as whistling or bird chirping.

"High frequency sounds occur at a place in the inner ear that is closest to the outside of the head, where damage typically occurs, and lower tones are perceived at a place that is closest to the inside of the head," said Neel.

"Parts of the ear that are responsible for the high frequency tones are more vulnerable to damage compared to the part that is responsible for the low frequency. That’s why as age progresses people start losing their higher and higher pitch hearing," said Ayaskanta Rout, a Ph.D. student in audiology.

Because most people have a hearing loss long before they do something about it, Neel believes that people may hear the sounds, but forget how to interpret them. She hopes to identify those sounds and design training materials to facilitate speech interpretation.

"We’re really interested in studying what kind of cues, or speech signals, people learn to use to identify speech sounds and what happens to their ability to use those cues as their hearing deteriorates and when the hearing aid is put back on them," said Neel.

A common complaint of those who visit the audiology lab is the difficulty to understand speech, especially in noisy situations, when wearing their hearing aids. According to Rout, the hearing aid tries to amplify everything for the user; however, this often makes it difficult, and sometimes even painful, for the person to understand others.

"As good as hearing aids are now, and as expensive as they are, they just don’t restore hearing to normal levels," said Neel.

So, while many things in life are uncontrollable, hearing loss is something that can be controlled or prevented in many situations. Simply turning the stereo down or wearing earplugs can make a difference in developing the irreversible process of hearing loss.