The oldest type of hearing aid is actually still used in modern times. If you see someone cup their hand behind their ear, you are witnessing the first form of hearing assistance in action. The first real hearing aids, however, were the long trumpets used by sailors to hear the voices of other sailors calling to them over long distances at sea. 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. Around the same time, the Metal Ear was created and sold to individuals with difficulty hearing. The Metal Ear was molded out of metal in the shape of an oversized ear and worn directly over the actual ear. During the nineteenth century the acoustic horn had been invented and was marketed under names like Auricles and Cornets. 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. In 1921 the first hearing aid using vacuum tubes was patented, but it wasn’t effectively used until 1934 because of its bulk. It consisted of a microphone, an ear receiver, an amplifier, and two batteries, which only lasted for a single day. Only incremental improvements were made in hearing aids after this until 1947, and the invention of the transistor. 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.

The digital circuit and the microprocessors allowed hearing aids to take a big leap forward. Many new features became possible such as noise and feedback management and directional microphones. Microprocessors also enabled greater audio clarity and miniaturization. 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. Digital technology first appeared in commercial hearing aids in 1987. The processor for these hearing aids was quite large and had to be worn on the body while a wire connected the 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.