Vanderbilt testing hearing aids

From: Nashville City Paper, TN - Mar 4, 2004

By M.B. Owens, bowens@nashvillecitypaper.com

As the U.S population continues to grow older, the need for hearing aids to assist in age related hearing loss is expected to increase. Hearing specialists called audiologists are trying to keep up with the latest technology breakthroughs like digital hearing aids.

Vanderbilt Medical Center's Bill Wilkerson Center for Hearing and Speech Sciences is at the forefront of testing and recommending the best of the new hearing devices. This research is performed at the Center's Maddox Hearing Aid Research Center.

"Because of the boom in technology, we are able to process signals in new ways," said Dr. Todd Ricketts, director of the Maddox Research Center. "Our job is to determine what technology is truly useful to consumers and what the audiologist can do when fitting a hearing aid to enhance the performance of the technology while minimizing any negative aspects.

Nationally there are approximately 30 million people that wear hearing aids and about 1.6 million are purchased annually, according to the Tennessee Association of Audiologists and Speech Language Pathologists.

The price for most hearing aids range from $900 to $3,000, with the average cost at $1,900.

Experts point out that there is no one hearing aid that is the best for everyone, just certain features that work better in some situations.

"When fitting someone there are a number of different things that need to be considered," said Dr. David Gnewikow, coordinator of audiology at the Bill Wilkerson Center.

Hearing aid size; cosmetic concerns; the amount of hearing loss and the appropriate technology must all be addressed individually. And to determine answers for those questions and make sure hearing loss is not being caused by a more serious underlying condition, audiologists perform a complete diagnostic evaluation on each patient.

Most people with hearing difficulties suffer from "sensorineural problems" related to aging, genetics or excess noise, Gnewikow said.

The latest trend - digital technology - is used in almost all hearing aids sold now. A digital hearing aid can easily be reprogrammed as a patient's needs change over time.

"One of the great advantages [of programming] is that it can be changed later," Larry Center, audiologist at Mid-State Hearing Aid Center in Nashville, explains. "The old analog devices had to be completely replaced."

There are about four manufacturers that make the top end hearing aids with similar technology, including Siemens, GN Resound and Widex.

Center of Mid-State sells the latest Widex model named Senso DIVA High Definition.

"One of the features that DIVA has is automatic directional intelligence," said Center. "An example would be the hearing aid would focus on the person talking in front of you rather than the sounds on the side. In this way the wearer can concentrate on the conversation."

Other features include the reduction of amplification on certain types of noises, such as machinery or internal whistling.

How digital hearing aids work
Digital hearing aids represent sound as a string of numbers referred to as digitizing. The sounds then are manipulated by applying mathematical formulas known as digital signal processing (DSP).

All digital hearing aids convert the new number values into amplified sound.

In the most basic digital hearing aid the DSP is relatively simple, increasing the level of sound at some pitches more than others and keeping the level of sounds from being too loud. The main advantage to a digital hearing aid is it can more precisely amplify desired sounds.

- Vanderbilt Bill Wilkerson Center)

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