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The History of Hearing Aids – From Seashells to Mini-computers

Thu, 09/11/2008 - 06:15 — Matt Jacks

Hearing aids may have a comical side to them (though not if you need one), and be a popular subject for mayhem in cartoons and from comedy shows; though less so nowadays in our increasingly sensitive times. But they have gotten smaller, more discreet and more effective as technological advances have come upon the scene, and this fact could be as much responsible for the lessening of joking asides and assaults as is the fear of legal action or the now encouraged thoughtfulness.

Not that the hard of hearing didn't get their own back by the, more than occasional, tactical use of their hearing aid. The machine deciding to pack up working when spoken words were not wanted to be heard was a very convenient excuse indeed! And much frustration it must have caused, to the apparent blissful ignorance of the disabled person involved. This too, can be gotten away with less now as the onward march of science brings more reliability. Though manual volume controls can still be slyly utilized if present, don't forget.

Trumpets are not always for blowing

But, think hearing aids and the image that pops up in your brain may well be the elderly (usually male) curmudgeon with his enormous ear trumpet. These earliest of hearing aids might well have been used by humanity for millennia; whether skillfully carved from wood, perhaps precious metal for nobles, rich merchants and the like, or fashioned from seashells or animal horns. Wide at one end and narrowing to a small tip at the other, and swung around to be pointed in the right direction these aids must have been seen in all cultures and ages.

The idea of a half-deaf Viking snapping off one of the twin cow horns from his battle helmet, hollowing it and cutting off the tip, before holding it to his ear when receiving orders on what coastal town to pillage next might be an unlikely one, but you just never know.

As time progressed, so did the lack of satisfaction held with this form of audio logical assistance. It was simply too undignified for some.

The Royal Houses of Europe, for example, objected most strongly to the sight of not so artfully hidden smirking from some of the mere mortals that surrounded them. In the good old days a dose of the lash would deal effectively with such impertinence, or there was even the executioner's axe to be called for. But democracy (not to mention revolution) was gathering steam, so even the regal step had to sometimes be a careful one.

Nevertheless, something had to be done.

Into the Lion's mouth

The solution came in the shape of an adapted throne. The royal personage could dispense with the ear trumpet by taking seat on the new thrones or other chairs which had openings in the fronts of the arms. When kneeling in front of the monarch, the servants, ambassadors, government ministers or other hangers on at the court spoke into these from a respectful few feet away. Inside this furniture was a tapering tube which sent the sound of the voices to a resonating chamber further up in the arms and the wings. The King or Queen could thus hear clearly without any unseemly shouting or unwanted close proximity of the speaker, which had been the only alternatives to the ear trumpets before this.

These chairs could also travel with the owner of course, an added bonus as those viewing from a distance need not know (or have constant reminders at the very least) of the hearing difficulties of the proud sovereign. This was of vital importance to the decorum, dignity or pomposity, depending on your point of view, of most royals.

Probably the best well known of these hearing aid thrones was that one which was crafted for King Goa the fourth of Portugal, in circa 1820. Here the armrests were crafted as splendid lions heads, roaring out their silent fury at any who would dare challenge the king. Those speaking would kneel and talk into one of the lions mouths and have their words come out of a tube grasped by his Majesty. Rarely had distance and nearness both been so well portrayed simultaneously.

Don't make a spectacle of yourself

Also in the 1800s came an attempt to aid the dignity of normal men and women, with the invention of the Clarvox Lorgnette trumpet in France. This lightweight ear trumpet was made of tortoiseshell and hung down from one side of a pair of spectacles. The color was to help it blend into the shadows, or at least not put up too much of a contrast against the black and dark gray suits or darker colored dresses of the time. It seemed a good idea, but was to prove to be too awkward.

Fancy a dome, urn or tube?

Around the 1850s came the Opera Domes or London Domes, as they were alternatively known. Manufactured from thin metal, and in a wide variety of shapes and sizes to allow for differing amounts of hearing problems, they were soon very popular.

At about the same time, with the optimism of the Victorian era sciences in full swing, there led to sometimes very enthusiastic but odd attempts to provide hearing and eye protection. Take for example the Urn, or to give it its full title; the Acoustic Table Urn. This heavy fitment was attached to a strong table and had multiply directed openings which were usually highly decorated with lattice work that were both pleasing to the eye as well as an aid to the working of the contraption.

The purpose of these was to take in sound from all directions in the room where it was situated, often as a centerpiece, boost the sound waves through an internal resonator, and send it to the user who would be seated at the table, through a carefully disguised tube.

Whether or not this early 'listening post' was effective is up for debate. But it wasn't helped by the lady of the house keeping on insisting that the wide openings were just perfect to be employed as flower holders, as was apparently the norm.

The ear tube used here surreptitiously was also later taken for more direct purpose by those not overly concerned by appearance or embarrassment. In the latter part of the nineteenth and early twentieth centuries it would not have been uncommon in cities around the world to see people, particularly senior citizens, talking to one another through tubes. One end here being held to the speaker's mouth, and the other directly to the listener's ear. A much shortened version of those seen in use on warships on old movies on TV.

Electricity sparks new life into the hearing aid

But times were changing again. Electricity was to be used for the first time in hearing aid patents in 1892, although none of these earliest electric pioneers would be developed successfully.

The next batch had more luck and by 1899 an electrically powered hearing aid could be purchased for around $400. This table sitting design with a microphone made of carbon, battery box and earpiece was far beyond the means of most, who worked for only a few dollars wage a week.

Even if it could be afforded, it would then be doubtful as to whether a 'sound' investment had been made or not. The first models did not work well, the main problem being the microphones which had to be made with a technique using carbon in dust form. Only a couple of years later however, the reliability and listening quality jumped ahead as carbon pre-formed as balls began to be used for this purpose. Though batteries that lasted for more than a handful of hours were rare, and would be for some time to come.

These microphones would differ in size according to the respective needs of the owner, with the mildly afflicted needing a microphone type only around a quarter of the size of those required by people with severe hearing difficulties. So in some ways things had remained the same despite the onset of electrical power, harkening back to the Opera Domes, which also varied in size some fifty years earlier.

Non-electric hearing aids were still being made and the Stethoclare a decade or so later would reach near peak performance for the timeframe involved. This name comes from the Greek word 'stethos' and the Latin 'clarus'. The literal translation of 'stethos' is actually 'breast' but many people associate it with sound because of the famous 'stethoscope' used by doctors to listen to their patient's heartbeats and other inner workings. 'Clarus' simply means 'clear' in English. This Stethoclare was a radically improved version of the earlier Acoustic Table Urn. It was still placed on a table and used via a tube, but was now only measuring around four or five inches across.

Bring on the bone-conductor!

The twenties and thirties would see improvements with vacuum tubes being used as a better delivery tool for the gathered sound in a hearing aid, and also the invention of the Bone Conductor in 1933. This might sound like the name of a cartoon character that leads an orchestra made up of skeletal musicians, but was actually a very effective way of helping people to hear by sending sound through the bone at the side of the skull behind the ear, and bypassing the poorly performing ear. If you could put up with the headaches.

Increased portability was now the name of the game for electric hearing aids, and the thirties and forties saw many designs from competing manufacturers. Yet, whilst this may have been a noble goal, the physical results were large, cumbersome and expensive.

The batteries were now better but still would not last for more than a single day, and also had to be carried in separate cases or pouches. The microphones were still quite large and obviously visible. To be worn around the neck and wired up to the headpiece or earpiece. Even with vacuum tube sorts the processing units still were bulky, though admittedly smaller than other types. All this gave something of a ‘mad scientist’ air to the unfortunate wearer, who were suffering quite enough anyway without the added problem of being stared at by everyone within sight. Children were particularly vulnerable for obvious reasons.

Three cheers for the transistor!

All this would be blown apart in 1948 as the transistor is invented. Truly a remarkable boon for all electrically powered components and devices across virtually every field of technology, and hearing aids were certainly no exception. The modern world has much to thank American scientists John Bardeen, Walter Brattan, and William Shockley for.

Now at last, true portability had dawned for the electric hearing aid!

They were to drastically shrink in both dimension and price as the transistors' advantages of cheapness, small size; low power drain and highly effective operation were to become clear to a marveling world.

Hard of hearing folks in the fifties were luckier than ever before. The new hearing aids could be worn underneath clothes or snugly in a pocket; only the earpiece could be seen and this fact greatly increased the user's self esteem. Now he or she did not feel they stood out a mile when in a group of people; they could relax more without worrying and be themselves.

Things were to get healthier as the decade grew. The second generation of transistors was smaller still and new magnetic microphones were superior performers. Models like the 'slimmette' were designed. Here the hearing aids were in flaps that came down from the sides of glasses, an idea borrowed from the Clarvox Lorgnette Trumpet more than a century previous and now infinitely improved. Having the microphone nearer to the ear gave a more normal impression of speech. Unless you didn't like to wear glasses.

Back to the ear

But that was not a problem for long, when now, as the fifties gave way to the sixties; models arrived that were over-the-ear or behind-the-ear. All in one unit that combined the battery, microphone and transistor circuit in an all in one molded design with a small individually built ear tube.

The first of this group were known as at-the-ear hearing aids because they were visible, protruding slightly as they did, but the later versions were increasingly more and more the products of better design for easy concealment. Completely so for those with longer hair.

1969 may be justifiably famous for Astronauts Neil Armstrong and Buzz Aldrin walking on the moon, but steps of a different kind were underway in the hearing aid industry as the first directional microphones were incorporated into products, leading to a more natural sounding world for the partially deaf.

Add this to the integrated circuitry that was now being applied to the best hearing aids in the early seventies to assist the user in distinguishing speech from background noise and the latest tiny batteries that allowed for ITC or in-the-canal aids, this meant that around ten years later analog sound processing systems were quite widely available that were almost completely hidden from view.

This availability increased still through the eighties, facilitated by the introduction of lithium batteries, and the dropping price was a bonus as well. The latest models now were providing sound through digital technologies. The hearing aid was turning into a mini-computer with the advent of DSP or Digital Signal Processing.

This had all led to programmable hearing aids, and their vastly improved fine tuning properties. At first purely analog, and then later digital, these were hearing aids which could alter their output or performance according to circumstance, need, or user preference. Operating modes which either could be pre programmed or adjusted by the user.

During the eighties as well, the idea of surgical implants to the cochlea was widely touted as a cure for deafness in cases where hearing aids can do no good, and the United States government approved these procedures for adults in 1985 and for children in 1990. But this subject is still one which raises much debate and controversy today.

The nineties saw hearing aids and hearing protection streak ahead in complexity. Two channel sound, automatic volume control or remote volume control for the smallest of ITC instruments that by now when worn were totally invisible to all. Then fully digital audio processors were developed that global research took up to produce a working system they named Adaptive Speech Alignment, which boasts multi-tone banding and dual processing. One each for recognizing vowels and consonants.

In addition to this the top of the range hearing aids have super advanced feedback controls, more self-assessment of listening comfort and memory cards for the remote control. Now, also the promise of micro-magnets implanted next to the eardrum, which will never need replacing.

Listening to the past, and future

So hearing aids have come an awfully long way indeed since their presumed origins of an ancient world citizen with a shell up to his ear. In comparison it almost seems farcical, but that was then and this is now. For, with all our space age gizmos, in essence hearing aids today provide exactly the same service that they always did. That of social inclusion for those with less than good hearing abilities, and that surely is worth its weight in gold, whatever century we happen to be living in. 

About The Author

Matt Jacks is a freelance copywriter providing tips and advice for consumers. His numerous articles offer moneysaving tips and valuable insight on typically confusing topics.

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Ear Trumpets, the Packington Collection
SY10, Shropshire, UK