The oldest type of hearing aid is in fact still in use today. Whenever you see someone cup their hand behind their ear, you are witnessing the first form of hearing assistance in action. Born out of necessity, the earliest tools used to aid hearing came about in the early 17th century. They were the long trumpets that sailors held to their ears to hear the calls of other sailors on distant vessels. 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. Although smaller, these devices were still so bulky that they had to be placed on a table or carried in a lady’s purse, using a flexible tube to convey the sound to the ears.
The first electric hearing aids arose out of the invention of the telephone, and appeared in 1898; they basically functioned like ear trumpets, but they did succeed in widening the frequency range people could hear through them. A hearing aid using vacuum tubes was patented in 1921. The vacuum tube – based hearing aids wasn’t commercialized and sold to the public until 1934 because of its large size and bulk. To operate, the hearing aid required the vacuum tube, a microphone, an amplifier, a receiver and 2 batteries. When first introduced the batteries only provided for 1 day of use. 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. In 1958 the integrated circuit was invented and was quickly incorporated into hearing aids, a trend that continued through the 1970s.
When microprocessors and digital circuitry became available, they too were used in hearing aids, creating features impossible before that time, such as multi-band technology, noise and feedback management, and directional microphones. The new technology had its downside too. Since each hearing aid was hand-crafted, prices were very high and wait times were long.
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.