Digital Hearing Aids Hold New Promise

By DENISE GRADY for NewYorkTimes.com

June 4, 1997 - DURING the last 20 years, Russell Frahm, a 79-year-old retired businessman in Tucson, Ariz., has gone through at least six pairs of hearing aids. The electronic components have varied, and so have the styles, from behind the ear to in the ear to the tiniest versions, hidden inside the ear canal.

"Whenever I changed," Mr. Frahm said, "I got the best thing available at the time. Hearing is very, very important to me."

Even so, he often missed what people were saying. In the dining room at his retirement community, where background noise is high, he said, "I couldn't join in the conversation because I couldn't hear."

About a year ago, Mr. Frahm's audiologist, Dr. Holly Hosford-Dunn, told him that a new device, a digital hearing aid, had become available. He became the first of her patients to try a set. Now, Mr. Frahm takes part in the dining-room discussions. "I can hear, not perfectly, but well enough to be able to communicate," he said. "I hear in conditions where I've never been able to hear before. Nothing in this world is perfect, including hearing aids, but this last pair is the best I've run into."

Two companies have marketed digital hearing aids in this country, and other manufacturers are planning to introduce them as soon as possible. Audiologists say the devices have great potential because they can be programmed to meet individual needs and adjust automatically to changing levels of sound in the environment. But there is some difference of opinion over whether the digital models now available represent enough of an improvement over other types to make their high cost -- $2,000 to $3,700 each -- worthwhile for most patients.

Digital hearing aids are, in essence, miniaturized computers. They convert sound to an electrical signal, and then to a digital signal, a numerical code that represents the intensities and frequencies of the original sound. The digital signal can be processed to meet the person's needs and then converted back to an electrical signal and then to sound. While earlier hearing aids were adjusted with a screwdriver, digital ones are programmed by a computer.

In conventional hearing aids, known as analog models, the sound is converted to an electrical signal but never to a digital one. Some analog devices do, however, employ digital technology to modify the electrical signal. Like the fully digital devices, they can be programmed to alter the signal specifically to compensate for a particular type of hearing loss. But those models are referred to as "digitally programmable," and the term "fully digital" is generally reserved for hearing aids that convert the sound itself to a digital signal.

Digital hearing aids were introduced in the United States last year by two Danish companies with American affiliates: Oticon Inc. in Somerset, N.J., and the Widex Hearing Aid Company in Long Island City, Queens. Oticon expects to sell about 100,000 digital hearing aids in this country this year, said the company's marketing director, Dr. Peter Mark. Widex has sold about 200,000 worldwide, the company president, Ron Meltzner said, but he declined to release United States sales figures.

Dr. David Fabry, an audiologist at the Mayo Clinic in Rochester, Minn., who does not work for any of the companies, estimated that by next April, 8 to 12 new digital hearing aids would be available, with more on the way, plus upgrades of existing models.

An estimated 28 million Americans have hearing losses, but only 6 million wear hearing aids. Many, with hearing losses ranging from mild to severe, are candidates for digital devices, though not every patient who meets those criteria will find the new models superior to other types of hearing aid. And people whose hearing losses are classified as profound are definitely not candidates. (Profound is defined as the inability to hear sound at any frequency unless its loudness measures 90 decibels or more.)

Dr. Hosford-Dunn, who wrote an article about digital hearing aids for the May issue of a trade publication, The Hearing Journal, has fitted more than 20 other patients with the devices in the last year. "They can make a major change in the way people function," she said. "The ability to carry on a conversation with competing noise is noticeably better in patients I've had for years whom I've fitted with these instruments."

Dr. Charles Berlin, director of the Kresge Hearing Research Laboratory at Louisiana State University in New Orleans, said the devices "would do for hearing aids what CD's have done for music." In a few years' time, he said, he expects that it will be possible to program digital hearing aids to tune in to specific voices that the wearer wishes to hear, and to block out particular household sounds, like refrigerators or air-conditioners.

But Ellen Pfeffer-Lafargue, assistant director of audiology at the League for the Hard of Hearing in Manhattan, said: "Digital hearing aids are not magic. When people hear digital, high-tech, programmable, they think that it will be quiet when they walk into a noisy room, that it will be like having normal hearing again, or better. It's not." Many of her patients who try the digital models prefer them, she said, but some reject them during the 30-day trial period legally mandated in most states before payment is required.

Dr. Mark Ross, a professor emeritus of audiology at the University of Connecticut at Storrs, who has worn hearing aids for 45 years, said people who were getting by with their current hearing aids might be wise to wait a while before investing in digital ones. More choices will become available soon, he said, and studies should be able to determine whether the devices really have significant advantages.

One factor that concerns Dr. Ross is that digital hearing aids are expensive, with the smallest, in-the-canal styles the most costly. Some conventional hearing aids cost less than $1,000, though others, with certain digital features, approach the price of the fully digital models.

Digitally programmable hearing aids have been available for about 10 years, and one of the advantages they share with fully digital types is that they cause far less distortion than many analog devices. In addition, Dr. Fabry said, "Programmability allows access to a greater number of controls than would be available on an analog device." Fully digital hearing aids also greatly reduce feedback, the annoying whistles that occur when amplified sound is fed back into the microphone. Programmability may also help reduce background noise, though that is not accepted by all audiologists. Dr. Fabry thinks that research on the use of directional or multiple microphones will ultimately lead to the greatest advances in helping people to hear speech in a noisy environment.

Another advantage of all the programmable devices, Dr. Fabry said, is that they can be adjusted from a remote location by means of a modem, saving patients a trip to the clinic.

"Certainly the potential for digital hearing aids is outstanding," he said. "But it would be a mistake to think that just because a hearing aid is digital it's automatically going to be better than the other devices out there. We have some good analog and digitally programmable analog hearing aids that are not going to be made obsolete immediately." More is known about fitting the older devices to a patient's hearing loss, he added, so for now audiologists may be able to make them work as well as a digital aid or even better.

Indeed, older programmable hearing aids held their own against one of the digital models in a recent study by Dr. Fabry and Dr. Michael Valente, of Washington University in St. Louis. The study included 60 patients who compared their programmable models with digital ones. "We evaluated the individual's performance in background noise," Dr. Fabry said. "We found that there were no significant differences in performance between the two types of devices."

Even so, he said, "a considerable number of patients preferred digital sound to the analog." Many found the digital hearing aids to be better at picking up very faint sounds. "There is no question," he said, "that digital is the way of the future."

FURTHER information about hearing aids is available from a national, nonprofit, consumer-education group, Self Help for Hard of Hearing People Inc., at 7910 Woodmont Avenue, Suite 1200, Bethesda, Md. 20814.

All inquiries will be answered, but a spokeswoman for the group asked that requests for information that are sent by mail include a stamped self-addressed envelope.

The organization maintains a web site at www.shhh.org and receives E-mail at this address: national@shhh.org.

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