Throughout history, there have been different forms of hearing instruments or devices that were used to amplify sounds. From the first hearing aid that was created in 1902 to today’s digital hearing aids, each of these devices was provided and fitted by hearing instrument specialists and audiologists. Manufacturers have produced master hearing aids. These referred to “machines that allowed dealers to select and try out different amplified responses”.
Hearing Aids from the 1920s
Hearing aids that were created in the 1920s utilized parts that were also found in telephones with batteries, which boosted the signal to amplify sounds. Boosters/amplifiers, microphones and receivers were all connected through cords, and the devices were worn on the body. Each element had different resonant frequencies and through assembling an appropriate combination, it was possible to establish an additive frequency response. Back then, companies typically only manufactured one model, so a large number of components were unnecessary. The leading hearing aid featured all of the main parts, and the dealer tested out various combinations on patients until they settled on something that worked.
Hearing Aids from the 1930s and Beyond
During the late 1930s, manufacturers made hearing aids by using vacuum tube technology that was developed for radios. This replaced the previous carbon telephone assemblies. The hearing aid devices continued to be worn on the body, with parts that were linked by cords. The amplification that these devices provided significantly improved. When vacuum tube-based, master hearing aids were produced, the process of testing out a variety of parts and components until the patient could hear their best was implemented. The hearing aid provider was able to order a hearing aid from the manufacturer with the same combination of components that the user preferred, but there wasn’t always a perfect correspondence of parts. This type of fitting, which could be viewed as a “substitution method” was used until transistor hearing aids became available.
In 1937, approximately 50,000 hearing aids were used in the U.S. In the late 1940s there were more than 100 large and small businesses that made hearing aids. Annual sales of hearing aids grew to more than 220,000 units by 1948.
Ear-level hearing aids and transistors appeared in the early 1950s. Transistorized master hearing aids were developed. The previous substitution method was no longer practiced. It was replaced by asking patients to listen to speech tests, as the hearing aid provider shifted between a variety of amplified responses at the different gain and output settings that were provided by the master hearing aid. Test results were used to choose a hearing aid from the provider’s inventory that matched up with the needs of each patient.
Computerized fitting software that is used today, is a modern version of the original master hearing aid. It’s a direct relative of the three computer-based systems that developed in the 1980s. When Starkey Hearing Technologies transformed the world of hearing aids by making custom hearing devices more popular, the performance of each hearing aid was chosen by proprietary computerized fitting algorithms that were established in the company.
Probe-tube microphone instruments were soon introduced, which used automated, computer-facilitated measurements and verified the fit by using prescriptive formulas. Hearing aids that could be programmed began making its way through the marketplace around the same time. Hearing instrument specialists who used computer-based programming devices were required to choose and manipulate the frequency-gain responses that were pre-installed within the hearing aids.
Even though the fittings that are used with master hearing aids have significantly evolved, one thing has stayed the same. A hearing aid fitter is still going to ask how it sounds and make sure that it is properly fitted. This shows how difficult it is to create an objective norm for an adequate hearing aid fitting, even with modern advances in fitting protocols.
If you, or a loved one, are in need of hearing aids, please get in touch with one of our hearing instrument specialists at Pure Sound Hearing Aids for a complimentary hearing test and consultation. We offer a variety of standard and customized hearing aids for your hearing needs.