Issues with hearing loss have been around for centuries, and people have searched for ways to enhance the hearing experience. There were a few attempts that seem quite strange today, but they were vast improvements for individuals back then. As ENT and Audiologists, we help people daily with hearing issues. And, hearing aids are designed to improve quality of life. We take a look back at how it all got started.
Hearing Aids Before Electricity
It's hard to imagine, but yes, electricity is used to power hearing aids. But, before its invention, people had to get creative. There has been evidence of instruments designed to help in hearing loss as early as the 13th century. They were rudimentary in design and built using hollowed-out horns from animals. The most popular were cows and rams.
These constructions looked a lot like a horn or trumpet and were placed against the wearer's ear. The horn didn't amplify sound, so it will come as no surprise they weren't that helpful. It acted more or less like a funnel. The hope was to capture additional sound waves and funnel them through a narrow tube. They were very cartoon-like and bulky.
The First Adaptation of the Electronic Hearing Aid
Alexander Graham Bell invented the telephone in 1876 three days after receiving his patent for the device. Surprisingly enough, the invention was conceived while Bell was teaching the deaf. The efforts he put into creating the device would later influence the first design of assisted hearing technology. Individuals who had hearing loss found they could hear better when they were having a conversation when the receiver was positioned against their ear.
It took another inventor with personal experience with hearing loss to take this idea and make improvements. Thomas Edison invented an amplifier that increased the decibels by about 15. The invention was called a carbon transmitter. An average person with hearing loss would need something around 30 decibels to hear better, but Edison was going in the right direction. The carbon hearing aid had its limitations. There was limited frequency, and a lot of background noise often accompanied the sound. Despite the feedback, they were regularly used from 1902 until the next invention.
Using Vacuum Tube
It was at the beginning of the 1920s when it was noticed there needed to be improvements to hearing aids, specifically the flow of electricity. Vacuum tubes were introduced and achieved this goal to the point of increasing the decibel level to 70. So, while the invention was helpful, it also had a setback — the size. How big do you ask? Roughly the size of a filing cabinet. Indeed, these devices were not portable making them a little inconvenient to wear. However, it got better. Just four years later they were able to combine the necessary components to fit into a small wooden box with a receiver. It was cumbersome and didn't only improve the sound of voices but all sounds in the area.
A wearable hearing aid didn't materialize until 1938. The contraption had multiple parts: an earpiece, receiver, wire, and battery. The receiver was attached to the front of the body, and the battery pack was often fastened to the leg. Circuit board hearing aids didn't come around until the late 40s. It was still a multi-piece affair that had a lot of wires and a unit that sat in the pocket. But, this design did have a circuit board and small batteries roughly the size of a button.
The transistor's invention did a lot for improving the size of hearing technology. The transistor was invented by Bell Telephone Laboratories and was able to control the flow of electricity with the flip of a switch. But, it wasn't just the electricity that it commanded — it was the volume as well. In 1952, an engineer named Norman Krim noticed the potential the transistor had in improving hearing aids. Krim went to work and developed the first wearable device that sat in the ear or just behind. The need for this invention was so strong that it sold 200,000 in its first year.
It took another decade until the first version of the hearing aid we know of today was developed. Manufacturers found they were able to make a transistor with silicone. The discovery allowed them to shrink the size of the device considerably. Zenith Radio created a version that allowed the microphone to be placed in the ear with the amplifier. A small wire connected them, and the battery unit was situated behind the ear. The design was so successful it remained more or less unchanged until the 80s.
New Designs Today
In 1996, the first digital hearing model was developed. By 2000, they were programmable giving each person the option to customize and tune their listening experience. In 2005, almost all hearing devices were digital and used the same technology as phones and computers. We've come a long way over the years, and manufacturers are always looking for ways to improve the experience. Through better amplifiers and binaural processing these new designs make it possible to get clearer sound without the traditional feedback or lag. There is also wireless connectivity that syncs to smart devices to improve sound.