Hearings aids are very interesting pieces of technology. The very first one looked like some sort of musical instrument placed inside the ear. Today, it is a small plastic device that can go unnoticed in front of those around you and be several magnitudes more effective. But how did it go from a large metal horn to a small piece of plastic? It all began with the telephone developed by Alexander Graham Bell in 1876.
In 1876, several people with hearing problems found it easier to hear through Bell’s telephone since the receiver was close to the ear; however, Thomas Edison thought of a better idea and developed a carbon transmitter in 1878 for the telephone that amplified the signal put into it. Although Edison was on the right path with electric signal amplification, speech was only amplified by around 15 decibels and the device was still large and heavy – hardly anything practical. To get a better perspective of decibels in terms of speech, a person raises their voice by 30 decibels to allow those hard of hearing to hear.
In 1907, Lee De Forest’s vacuum tube hearing aids produced 70 decibels of amplification which far surpassed the 15-decibel amplification that Edison created. Although this model surpassed that of its predecessor, it weighed a hefty 100 kg and was still very large – hardly transportable for daily use. The main point of this model was to prove that speech could be amplified without a person raising their voice. However, by 1924, this 100kg was reduced to 4kg and allowed the device to fit in a small wooden box. Because of this advancement in vacuum tubes, the hearing aid was finally portable; however, not many people wanted to carry it around due to not wanting others to know about their hearing impairment.
The first wearable hearing aid was developed by Aurex Corp. in 1938 which consisted of a small earpiece and wire connecting to a clip-on amplifier/receiver. This design was only made possible by Norma Krim’s development of the subminiature vacuum tubes that required less power in addition to their smaller size. This product became much more popular on the market as they were more hidden from people’s view when in use; however, they still had to use a strap-on battery pack.
Bell Telephone Laboratories in 1948 invented the transistor which allowed the production of transistorized hearing aids. This invention paved the way towards more compact models where batteries, amplifier and microphone were put together into one small unit. The only problem with these models were that they were still hard to hide when in use. It wasn’t until the late 1950s that hearing aids could be entirely worn at the ear.
The Otarion Listener developed by Otarion Electronics in the late 1950s was the first hearing aid that could be worn completely at the ear by storing electronic pieces in eyeglasses. This eyeglass infused hearing aid idea began to spread at it was much more practical to wear and easy to conceal. Even people with perfect sight wore these glasses-infused hearing aids because of its concealment.
Zenith Radio then developed a behind-the-ear model in 1964 that only weighed 7 grams. This device composed of an integrated circuit amplifier, a 1.2V button battery and microphone. Basically, everything besides the microphone is put into one unit and clipped to the ear.
Soon, the digital age rose up as programmable models became available in 2000 that allowed for fine-tuning and increased flexibility. By 2015, these hearing aids are compatible with several smart devices such as our phones to allow automatic sound adjustment and focusing. These are rechargeable as well and are hardly noticeable to someone who is unaware of it.