The strategy originally used as a hearing aid remains in use to this day, the instinctive gesture to cup a hand behind the ear to better collect 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 type of hearing aid sold in the 17th century was fashioned of metal and worn over the user’s own ears; it was called, unimaginatively enough, the Metal 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. 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. Unfortunately, transistors were also sensitive to dampness, so it took until 1952 until usable transistor-based hearing aids were made available. In 1958 the integrated circuit was invented and was quickly incorporated into hearing aids, a trend that continued through 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 new technology had its downside too. Since each hearing aid was hand-crafted, prices were very high and wait times were long.
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. The first all-digital hearing aid was introduced in 1996, and advances in technology have now made them the standard, possessing features undreamed-of by the 17th-century ladies with their ear trumpets.