The oldest type of hearing aid is in fact still used today. Whenever you see someone cup their hand behind their ear, you are witnessing the first form of hearing assistance in action. 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.
These evolved into smaller versions of the ear trumpet in the late 17th century. The ear trumpet was a portable cone or trumpet-shaped device. The narrow end was inserted into the ear and the flared ear was pointed at the sound. 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. In the 19th century smaller forms of these acoustic horns were marketed as Auricles or Cornets. These devices were portable, but cumbersome. The end collecting the sounds was generally placed in a strategic orientation on a table or carried in a purse. A flexible tube then carried the sound to the ear.
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. Only incremental improvements were made in hearing aids after this until 1947, and the invention of the transistor. It took a full five years – until 1952 – for transistors to find their way into hearing aids. The engineering challenge that had to be solved was keeping the transistors dry since they are very sensitive to moisture. 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 new technology had its downside too. Since each hearing aid was hand-crafted, prices were very high and wait times were long.
In 1987, however, the first commercially successful digital hearing aid appeared; it was a model with body-worn electronics with a connection to a receiver in the ear. All-digital hearing aids became available in 1996 and have been the standard ever since. The features and capabilities of modern digital hearing aids are truly marvelous. What will be next in the timeline of hearing aid technology?