Today’s hearing aids are marvels of modern design. And proof positive of an aspect of Moore’s law, which states that computer-based machines will become smaller and faster as transistors continue to become more efficient. But the hearing aid goes back a long ways.
Hearing “trumpets” date back to at least the 16th century — wide at one end and narrow at the other — and were made from a variety of materials. Eventually advances in physiology led to the discovery of “bone conduction”— wherein vibrations of the bones in the skull actually transmit sound into the ear canal — and devices that were placed behind the ear to focus sound waves were developed in the 18th century.
But none of them were small and subtle.
The 19th century saw a wide variety of disguised hearing aids that weren’t exactly small, but not as obvious. British monarchs even had cunning amplifiers installed in their thrones so they could hear their subjects better without announcing to the world their loss of hearing.
But the harnessing of electricity and the development of the telephone are the direct foundation of today’s artificially amplified hearing aids. The first were boxes worn around the neck, complete with batteries. These gave the user a few hours of better hearing … and probably a sore back.
But like computers, batteries became smaller and smaller over the course of the 20th century. The invention of the transistor in the 1950s ushered in smaller and smaller amplification hardware. Although the transistor radio is what we commonly think of, transistors were actually used in hearing aids a few years before the first transistor radio hit the market.
With transistor technology, hearing aids became small enough to fit in units that could be supported by the user’s ears. The next step was the onset of digital technology, which hit the market in earnest starting in the 1990s. This not only continued the trend of units becoming smaller, but also far more powerful and feature-laden.