In electronic hearing aids, a microphone's audio signal is fed into an electronic circuit which amplifies it. The greatly-increased audio signal is fed into the ear canal through an earphone. The amplifier circuit was originally based upon one or more vacuum-tubes, powered by a battery pack. As early vacuum tubes, microphones, and earphones were rather bulky, so was the housing for the circuitry. Large vacuum tubes, having a heating element and a need for fairly high voltage in another part of the tube, required a rather substantial battery pack. This battery pack was identical to that needed to power the portable radios of that time, which also required the use of earphones.
The earliest manufactured hearing aids were about the size of a cigar box. Mounted to the front of the box was a carbon microphone, very similar to the mouthpiece of one of those old hand-cranked wooden wall phones. This box was worn on the user's chest, supported by a strap which ran around the back of the neck. To disperse the weight, the heavy battery pack was worn in a leather case, which could be belted about the waist. A headphone, similar to those worn by radio and telephone operators in old movies, was held to the ear by a springy band, which clamped upon the sides of the skull. To the hearing-impaired of the 1920s, the hearing improvement may well have been worth the weight and ungainliness of the apparatus.
By the mid-'30s, further reduction in the size of vacuum tubes made it possible to have a bakelite hearing-aid case of about 1"x 3"x 5", with a built-in microphone. The earphone was still fairly bulky, but was smaller and lighter than that of the earlier device. The smaller tubes needed less power, but the slightly-smaller battery pack was still carried in a belt pouch.
World War 2 was responsible for a drastic shrinkage in the size of vacuum tubes, in response to a need for complex-but-compact circuitry such as airborne radar units and electronic proximity fuses in anti-aircraft artillery shells. The war was barely over when the manufacturers of hearing aids and portable radios started making use of the new subminiature tubes. By 1950, the vacuum-tube hearing aid had reached its zenith. It was housed in an attractive plated metal shell about the size of a pack of cigarettes. The smaller new batteries joined the microphone and the tube circuitry inside this shell. A thin wire led to a lightweight miniature earphone made of caucasian-tinted plastic and pinkish anodized aluminum. It had a resilient transparent nubbin which plugged directly into the ear opening, with no more need for a supporting headband. This compact and attractive device must have seemed marvelously liberating to long-time hearing-aid users.
The transistor was invented in 1949, and fully developed and marketed by the early '50s. It was soon exploited by the cutting-edge engineers and designers of the hearing-aid industry. In Reader's Digest magazine, when I was about 8 years old, I saw an advertisement for the first of the new transistorized hearing aids. At the time, considered a marvel of miniaturization. It consisted of a curvilinear "flesh-colored" plastic shell which fitted behind the ear. This contained the transistor circuitry, some tiny disc-shaped batteries, a miniature microphone, and a tiny earphone. A clear rigid tube led from this over the top of the ear and plugged into the ear canal. I found this to be deeply fascinating. At the bottom of the ad was an invitation to send for a free model of the device.
To me, at that time, the combination of "free", "model", and "transistor hearing aid" was incredibly alluring; to the extent that I successfully composed and mailed-off a request for one of them. For the life of me, I can't remember what it was about hearing aids that made me so interested in the subject. All I can imagine is that it was the idea that, if hard-of-hearing could use one to attain normal hearing, a person of normal hearing who used one would attain superhuman hearing power. Granted, super hearing ability was a minor suit in Superman's deck of attributes, but you had to start somewhere, if you wanted to achieve super-humanity but were unfortunate, in not having been born on another planet. The still-continuing sales of "X-Ray Spex" to youth attest to the universality of that sort of thinking.
I had expected something like a small kit of plastic parts, similar to the model aircraft and automobile kits I had recently begun building. You may easily imagine my disappointment when it actually arrived, and I saw that it was nothing more than a postcard with an actual-size photo of the hearing-aid printed on it in black and white, with no flesh coloration. It was perforated around the edge of the pictured hearing aid, so it could be punched-out and hooked over the ear to demonstrate its diminutive size and discreet form.
You may have more difficulty imagining the extent of my chagrin when I read, printed on the back of the card, that I could expect to be called upon soon by one of the company's representatives. Uh-Oh! I instinctively knew that this was going to lead to some sort of trouble. And I had already punched out the "hearing-aid model", colored it "flesh" with a crayon, and hooked it over my ear in front of a mirror.
However, using an inherent sanity-preserving mental facility of youth, I was able to successfully suppress all thought of the impending awkwardness. This worked very well for two weeks or so, until the hearing-aid company's area salesman knocked on our door. He had driven from Paducah, KY, a one-hour drive in the early '50s, to demonstrate the product to "Mr. Jimmy Wilson", of this address. Uh-Oh, indeed! I was hidden in the back of a closet well before the hot and sweaty salesman had finished explaining his presence at our door to my bewildered Mom.
I can easily imagine his chagrin when told that "Mr. Wilson" was eight years old, and possessed of normal hearing ability. She then added something like, "He hears so well that he can probably understand every word we say, no matter where he is in this house". Moms know all.
I had always been astounded at how lightly I got off on that caper, unlike many others; until I recently learned of a similar incident in my Mom's past, when, at a young age, she responded to an invitation to accept a "free" book from the Book-Of-The-Month Club.
In the '60s and '70s, a popular type of hearing aid was built into the frames of eyeglasses. As I have always worn glasses, I could well imagine how I would look wearing that type, and had no desire for a model. Current hearing aids take advantage of the micro-miniature electronic technology developed for the space and defense programs. The entire unit, batteries and all, fits entirely into the ear canal. I have not yet seen a free model offered, but if one were, I'm sure it would be a (small) disappointment.
Jim Wilson © 2001