Hearing Center Network

When the first electronic hearing aids appeared on the market in the 1920s, the average American was only expected to live into his or her mid-fifties. At that age, our sensory, neurological, and cognitive brain functions are largely intact. Most people suffering from hearing impairment at that time had a conductive type of hearing loss (blockages in the ear that impede or block the movement of sound, such as scar tissue from infections or a damaged ear drum).

Fewer people suffered from SNAPS, which usually occurs when we age. So, in the 1920s, most people simply weren’t living long enough to develop the intelligibility and cognitive difficulties associated with SNAPS.

By the 1940s, with the development of antibiotics and new surgical techniques, there had been a reduction in conductive hearing impairment. And by the 1970s and 1980s, our life expectancy had increased dramatically and more people were living into their sixties and seventies. This contributed to a significant increase in the number of hearing-impaired people with SNAPS.

Today, people are living well into their eighties and nineties and many experience the age-associated reduction in cognitive capacity that contributes to a more severe SNAPS profile. Modern medical treatment has reduced the incidence of the conductive type of hearing loss to a very small percentage.

Amplifiers: The hearing aid amplifiers created to help the early conductive type of hearing loss was not complicated. The devices were simply amplifiers that increased the volume of all sound coming into the ear. With varying degrees of success, this increase in volume allowed people to hear better despite blockages in the ear.

For those who did have SNAPS, hearing aids that simply amplified sound provided excessive loudness and little assistance. The hearing aids had only a few parameters that practitioners could adjust. Understandably, these people were dissatisfied.

Transistors Technology: When the transistor was invented in 1951, it allowed hearing aids to be made much smaller. For the next thirty-eight years, hearing aids contained up to twenty transistors. This allowed hearing aids to control loud sounds without as much distortion and provided better tuning capability for bass and treble sounds. This translated into more audibility and comfort for clients.

In 1989, microprocessors increased a hearing aid’s capability by allowing almost 40,000 transistors in a single aid. This enabled automatic volume control which had the capacity to provide even more audibility and better control of loud sounds.

Surprisingly, an industry study conducted as late as 1990 found that despite the advanced capabilities of hearing aid technology, a significant percentage of hearing aid users were dissatisfied with their hearing aids—41% described themselves as less than satisfied (Kochkin 1990).

Digital Technology: The concurrence of recent advances in both cognitive science and digital hearing aid technology created a new universe of opportunity for hearing correction. In the last decade, scientists have discovered how the brain processes the information delivered from the ears to create the textures, dynamics and rhythms we experience as sound and speech. New methods of brain imaging and new discoveries have prompted scientists to call 1990-2000 “The Decade of the Brain.”

Also during this time, engineers created more intelligent hearing aids that could be precisely tuned and miniaturized for comfort. In 1997, the first practical and fully digital hearing aids were developed. Today, each hearing aid can have as many as 2.5 million transistors. This allows for the detailed tuning of hearing aids to maximize audibility, shape sound presentation to be as natural and clear as possible, and filter out background noise in favor of a preferred speaker’s voice.

Statistics nationwide show that even with these highly capable devices, one-in-four high-tech digital hearing aids are returned by unhappy clients (Strom 2001). People even reject digital hearing aids two-to-one over simple amplifier hearing aids (Strom 2001). This indicates that there are still significant problems that have not been addressed.

The audiometric instrumentation used for testing a person’s loss of audibility and speech comprehension has been essentially unchanged over the past eighty years. Currently, there is no additional testing required or available to practically evaluate a person’s highly individual SNAPS profile anywhere in the international hearing aid community.

Over the years, the methods and instrumentation used to fit hearing aids have changed. However, all of the new methods relied solely on diagnostic information obtained from primitive hearing test data.

From the 1920s to the mid 1940s, people were lucky to get amplified sound with minor adjustments for loudness and low frequency sounds. Clients subjectively compared the performance of one setting to another setting. However, by 1947 two independent studies (The Harvard Report in the U.S. and the British MedResCo report) concluded that a single tonal setting would be appropriate for most hearing losses.

What is surprising is that neither study differentiated between people with conductive hearing losses and those with sensorineural impairments, even though these populations had vastly different types of hearing loss.

By the 1970s, new prescriptive methods had been developed. They were based principally on the few audiometric tones measured with the audiometer. Practitioners made calculations or “philosophical” judgments to best approximate the amount of sound needed for any given hearing loss.

New instruments were developed to analyze sound to ensure the hearing aids actually provided the gain promised by prescriptions. Other measurement techniques were developed to perform hearing tests for the improvement of audibility while the client was wearing their hearing aids. This method was not widely used, but several conscientious practitioners attempted to verify the audibility benefit their clients received.

By 1983, it was possible to objectively measure the actual sound delivered into the ear canal of a client. This allowed practitioners to better determine if the actual sound delivered by a hearing aid achieved the prescribed level.

Through the 1990s, manufacturers developed many variations of prescriptions. However, another nationwide survey, conducted in 1997, revealed that customer satisfaction remained largely unchanged: 46% of respondents were less than satisfied with their hearing aids (Kochkin 1999). Many were getting so frustrated that 16% reported they didn’t use their hearing aids at all (Kochkin 1999).

When digital hearing aids entered the market in the late 1990s and early 2000, they had sixty or more controls that could be modified to affect sound quality, audibility levels, and performance in the presence of noise.

Given the flexibility of these hearing aids, there were many different ways the hearing aid could be tuned to achieve the simple prescriptive targets created for the earlier amplifier hearing aids. This was challenging for the few practitioners who used objective measuring instruments, since achieving the target prescriptions with digital hearing aids still failed to satisfy many clients.

At that point nearly all practitioners gave up on using objective measurement instrumentation. Instead, they became dependant on the algorithmic fitting methods of the manufacturer. Algorithms are complex computer formulas that do the work for you. This algorithmic method was an attempt to use the logic of science and engineering to choose the complex settings for the hearing aids.

When this algorithmic method failed to produce successful and satisfied clients, the manufacturer’s altered their hearing aid delivery strategy to decrease the cost of the hearing aids, and therefore decrease the expected value, since the practitioners were not able to use the hearing aid technology effectively to produce the benefit and value the clients needed.

This began a process of changing the delivery system to one that merely delivered hearing aids as economically as possible through low service outlets and HMOs.