When was the first hearing aid? The first hearing aid was an ear trumpet described in 1624 by a French priest and mathematician called Jean Leurechon.
These days, people with hearing loss can buy pretty advanced hearing aids that have different settings depending on the situation. They can be directional or they can cut out background noises. Hearing aid companies are currently working on hearing aids that encompass AI. One of the biggest problems with losing your hearing is that you lose the ability to hear high frequencies. You might think that this means you cannot hear high frequency sounds and the rest are fine, but the problem is that simple sounds, such as speech, are a mix of high and low frequency sounds. The basic sounds might be low or medium frequency, but a lot of consonants are high frequency. consonants, such as ‘s’, ‘f’, ‘sh’, ‘ch’, ‘h’, and ‘t’. Vowels tend to be lower frequency sounds. Imagine how hard it is to understand what someone is saying if you can’t hear any of these consonant sounds. So much of the information will be lost. We think hearing loss means not being able to hear speech. People with hearing loss can hear speech, but they have a very hard time understanding what is being said.
When we are young, our ears can process sounds in a range between 20 Hz to 20,000 Hz. As we age, we naturally begin to lose the ability to hear the upper frequencies. When we hear, the shape of our outer ear catches sound waves and funnels them through the ear canal to the ear drum, making it vibrate These vibrations are carried from the ear drum to the cochlea by three tiny bones called the malleus, incus, and stapes (hammer, anvil, and stirrup). The cochlea contains microscopic sensory cells called hair cells, which have tiny projections called stereocilia. Movement of the fluid bends the stereocilia, causing the hair cells to produce signals that are passed through the auditory nerve to the brain. The hairs at the front of the cochlea register high frequencies and the ones towards the back register lower frequencies. We lose our high frequency hearing first because the hairs at the front are more likely to be damaged than the ones at the back.
The first recorded use of a hearing aid is by the French priest Jean Leurechon in 1624. He is not the inventor. He wrote about them in a manuscript called Récréation Mathématique and he talked about people using tubes shaped like a funnel, made of silver or copper, that people held to their ears to hear better. They work along a principle that you will have tried yourself. If you ever find yourself in a position where you can’t hear something clearly, say on a windy day, you will naturally cup your hand behind your ear. This serves the purpose of increasing the size of your ear and directing more sound waves into your inner ear. However, it cannot help you hear high frequencies because that is damage that has happened inside the ear.
As to who invented the hearing trumpet, there is really no way of knowing. There are some reports that the Roman historian Pliny the Elder in the first century AD used parchment cups behind his ears to hear better. In modern times, an Italian physician and student of Galileo, Paolo Aproino, appears to have given such a device to Galileo in 1612.
Electronic hearing aids were first invented in 1898, shortly after the invention of the telephone and the microphone. Miller Reese Hutchison invented the Akouphone. It captured a weak signal and used an electric current to amplify the sound. It was fairly large, but after a few innovations, it could fit into a purse. Things started to rapidly improve after the invention of the transistor in the 1940s. It made hearing aids much smaller, last longer, and made their sound much clearer. Researchers began experimenting with digital sound processing in the 1960s, although the computers were far too large to fit inside a hearing aid. Wearable digital hearing aids appeared in the 1980s, and fully digital hearing aids became commercially successful in the 1990s.
Modern hearing aids are very clever and can be programmed to the individuals specific hearing loss. They can be programmed to amplify certain frequencies. If a person has lost a lot of their ability to hear high frequency sounds, they will still have those hairs but they will be very insensitive. The hearing aid will leave the frequencies they can hear alone, but amplify the ones that they can’t to the point where they can hear them. This still doesn’t work if the person has completely lost the ability to hear high frequencies. Another trick modern hearing aids can do is to lower the frequency of the inaudible sounds. They can detect high frequency sounds, such as s or t, and automatically lower that frequency to a point where the person can hear it.
The latest step is AI. Some modern hearing aids already contain neural networks that have been trained to recognize speech and separate it from background noise. This is particularly useful in places such as restaurants, where traditional hearing aids have difficulty because simply amplifying everything makes all of the competing conversations and background sounds louder as well. As the technology improves, hearing aids should become increasingly good at identifying what the wearer is trying to listen to and suppressing everything else. And this is what I learned today.
Sources
https://en.wikipedia.org/wiki/History_of_hearing_aids
https://hearinghealthfoundation.org/blogs/hearing-aid-history-ear-trumpets-european-royalty-earbuds
https://www.healthline.com/health/high-frequency-hearing-loss#management
https://www.tandfonline.com/doi/full/10.1080/21695717.2017.1335267
https://it.wikipedia.org/wiki/Paolo_Aproino
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