Tracing the History of Hearing Aid Technology

The earliest hearing aid is probably instinctual, cupping one hand behind the ear and using it to capture faint noises and thus hear them more clearly. 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. 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.

Electric hearing aids came out in 1898 on the heels of the invention of the telephone. They were not too dissimilar from the ear trumpets that preceded them. However they did noticeably expand the range of frequencies that could be amplified. In 1921 the first hearing aid using vacuum tubes was patented, but it wasn’t effectively used until 1934 because of its 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. 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.

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. Unfortunately, these devices were expensive and had to be hand-crafted, requiring a wait of several weeks before you could obtain one. 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.