The strategy originally used as a hearing aid is still in use to this day, the instinctive desire to cup a hand behind your ear to better capture sounds so that you can hear them. The earliest technological hearing aids were used by sailors in the early 1600s, which took the form of a long trumpet inserted into the ear and used to hear other sailors calling to them over long distances.
Later in the seventeenth century, smaller versions of these ear trumpets had been adapted to help those with hearing loss; they took the same form, that of a cone-shaped device pointed at the source of the sound and inserted into the ear. Another form of 17th century hearing aid was called the Metal Ear, and that’s exactly what it was – a pair outsized ears fashioned out of metal and worn over the wearer’s own ears. Fast-forwarding to the 19th century, the next innovation was a type of acoustic horn sold under the names such as Cornets or Auricles. They were usually smaller in size, designed to be carried in a lady’s purse or to be placed on a table with a flexible tube conveying sounds to the user’s ears.
The invention of the telephone led to the invention in 1898 of the first electric hearing aids; they were primitive and much like the ear trumpets, but they did allow people to hear more frequencies. The first hearing aid using vacuum tubes was patented in 1921, but no successful version of it was sold until 1934 because it was so big and bulky. Because of the vacuum tubes, it needed an amplifier, a microphone, an ear receiver, and two batteries that, despite their size, only lasted for a day. Innovation in hearing aids stalled at this point for some time. The next round of development was made possible by the invention of the transistor in 1947. Even then it wasn’t until 1952 that a transistor-based hearing aid became practical, because it turns out that transistors were sensitive to dampness. The next round of innovation was fueled by the integrated circuit – first developed in 1958. This technological advancement lasted in the 1970s.
At that point, digital circuitry and microprocessors became available, offering new levels of audio clarity and miniaturization, and they began to be used in hearing aids with features such as noise and feedback management, directional microphones, and multi-band technology. The problem with these improved hearing aids, however, was price and availability; each unit had to be made by hand and often involved a long wait. The first commercially successful digital hearing aid was created in 1987, and used a body-worn processor connected via a wire to a receiver in the ear. 1996 saw the release of the first all-digital hearing aids, and that technology has been used ever since, constantly improving to provide features that 17th-century users could never have even dreamed of.