1600s & 1700sDuring the 1600s and 1700s, hearing aid “trumpets” were popular. Wide at one end to gather sound, and narrow at the other end to direct amplified sound into the ear, early hearing aid trumpets were fashioned from animal horn, sea shell and glass. Later, common metals – such as copper and brass – were used. Trumpet-style hearing aids were shaped in various styles, depending on customer preference and degree of hearing loss. Ludwig van Beethoven was one of the more notable aficionados of hearing aid trumpets.
Also during the 1700s, “bone conduction” was discovered. This process transmits sound vibrations through the skull to the brain. Small fan-shaped devices were placed behind the ears to collect sound wave vibrations and direct them through the small bones behind the ear.
1800sDuring the 1800s, efforts to conceal hearing aids began. Though still quite large, hearing aids were designed to be decorative accessories, and integrated into collars, head wear, bouffant hairstyles and clothing. They were sometimes covered in flesh-colored or hair-colored enamel. Some attempted to hide them in full beards. Members of royalty had hearing aids built right into their thrones. Special tubes were incorporated into the arm rests to collect the voices coming from visitors kneeling before the throne. The voices were channeled into a special echo chamber and amplified. The sound then emerged from openings near the monarch's head, with no one the wiser.
Also in the 1800s, ear tubes were introduced. One end was held to the speaker's mouth, and the other end placed directly to the listener's ear. Not very subtle, but quite effective.
1900sIn the early 1900s, the advent of electricity, coupled with Alexander Graham Bell's work on the telephone, ushered in a “new generation” of hearing aids that electronically amplified sound via a carbon microphone and a battery. Worn around the neck, these hearing aids were cumbersome boxes containing visible wires and a heavy battery that lasted only a few hours. Sometimes even weightier “battery packs” were worn on the body to extend the hearing aid's life.
Luckily, battery miniaturization soon arrived, drastically reducing hearing aid size. And, in the 1950s, the invention of the transistor changed hearing aid technology totally. A transistor is simply a switch with two settings: on or off. By combining multiple transistors, you get more combinations of on/off switches which leads to an increased number of functions. In fact, transistors were used in hearing aids two years before they were used in transistor radios.
By making transistors out of silicon, hearing aids were again able to shrink in size. First they became “body aids”, and then ear-friendly instruments worn behind the ear, in the ear shell, or ultimately, within the ear canal.
By the mid-1990s, digital hearing aid technology ruled. Digital circuitry allowed sound to be amplified, reduced, filtered, and directed, as needed. Hearing aid programs could be customized to a user's lifestyle – soft amplification for quiet home settings, targeted amplification of voices in restaurants, diminished wind noise on the golf course, and so on. Digital programming even helped eliminate feedback!