Can You Hear Us? Hearing Aids and their Electronics
February 22, 2023
There’s a Keystone in every great invention.
Hearing Aids and the Technology Behind Them
A true testament to the success of technology is the effect it can have on society, and how different advancements can drastically improve a person’s life. The hearing aid could be heralded as arguably one of the greatest technological advancements we’ve ever seen; transforming a once discriminatory disability into a simple characteristic that no longer hinders quality of life. 
While brilliant minds such as Beethoven, Helen Keller, and Thomas Edson thrived in their eras while being deaf or dealing with hearing loss, the many variations of hearing aids and instruments have allowed millions of people throughout time to capture or regain the ability of hearing and enjoy everything sound has to offer.
The History of Hearing Instruments and Aids
The art of amplifying hearing has been around since the 17th century, where ear trumpets, hearing fans, and speaking tubes were used to amplify sounds and assist the partially deaf. Made in a variety of shapes and sizes, ear trumpets gained popularity and became symbols of wealth, often made from sheet iron or animal horns and decorated with ornate designs.
Fast-forwarding to the 1800’s, the invention of the telephone was really the initial jumpstart to the invention of the electric hearing aid. Mimicking the telephone’s ability to control volume, frequency, and sound distortion, the first electric hearing aid was invented in 1898. The Akouphone, invented by Miller Reese Hutchison, used a carbon transmitter and electric current to amplify weaker signals. By 1913, Siemens became one of the first companies to mass produce electric hearing aids, however they were bulky and not easily portable.
Vacuum Tube and Transistor Hearing Aids
In 1920, Naval engineer Earl Hanson patented the first vacuum-tube hearing aid. The Vactuphone used a telephone transmitter to turn speech into electrical signals, amplifying those signals into a receiver. The original Vactuphone was bulky and weighed around seven pounds, but technological advancements going into World War II provided the ability of miniaturization. By 1948, many hearing aids like Zenith’s Miniature 75 Vacuum Tube Hearing Aid were conveniently pocket-sized.
The development of transistors by Bell Laboratories significantly improved hearing aids. Transistors were smaller and required less battery power, while also producing less heat during operation and offering increased reception. To extend battery life, the 1952 Sonotone 1010 used a transistor stage along with vacuum tubes. The size of these transistors led to developments in miniature, carbon microphones.
Analog and Digital Hearing Aids
Analog hearing aids became the next wave of sound-amplifying technology with the help of the microprocessor. Analog multi-channel amplitude compression devices enabled the separation of audio signal into different frequency bands. Based on the environment and sounds, the frequency bands were able to adjust the analog sound wo weaken louder noise and amplify softer noise. Although these multi-channel amplitude compression hearing aids still used external minicomputers, the concept of multi-channel amplitude compression would lay the foundation for fully digital hearing aids.
The first completely digital hearing aid was created in 1987 by the Nicolet Corporation. Today, digital hearing aids carry the same features as analog hearing aids, but sound waves are converted into digital signals, utilizing microchips to examine, decipher, and store sounds within different system settings.
Today’s Hearing Aids
Hearing aids today are all completely digital and carry features that pair easily to other everyday technologies. Features such as wireless connectivity provide hearing aids with the ability to stream audio from phone calls or music, while T-coils provide specific microphone settings that allow for better listening results on landline telephones. Noise reduction systems, Bluetooth compatibility, and rechargeable batteries also make today’s digital hearing aids suitable for any and all scenarios, whether it be outside in a crowded environment or inside a quiet restaurant.
"Made for iPhone” hearing aids have also been introduced to make life even easier for those streaming phone calls, music, and podcasts directly from iOS devices.
Hearing aids must be able to withstand a wide range of environmental conditions, from temperature swings to sweat to drops (shock and vibration). A number of Keystone products can be found in modern hearing aids and the electronics that support them, including Battery Clips, Contacts & Holders, PCB Test Points & Terminals; and PCB Pins, Plugs, Jacks & Sockets.
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