Old-fashioned hearing aid

Posted: Sunday, January 18, 2015 12:00 am
By Barbara Carney Special to the Tribune-Star
Hearing aids which now fit snugly into the ear have become almost invisible to the observer. But, this was not always the case. The pipe-like structure shown above is an example of an early device designed to help those with hearing difficulties. It was called a tin ear trumpet and was invented between 1650 and 1700. The object was still in use well into the 1800s.
The way it works is simple. The individual with audio problems holds the narrow portion at the end of the tube to his or her ear, while the other person speaks into the larger, round end. Sound pressure waves enter through holes in the large bell end of the trumpet. As the sound waves travel into and through the narrower tube, they are condensed into smaller and smaller waves, increasing the sound wave pressure into the ear. The degree of pressure increase depends only on the relative sizes of the large and small openings.
Recent experiments by staff members of the Vigo County Historical Museum led to the conclusion that the ear trumpet does indeed amplify sound. Even more apparent, however, is the change in sound quality, which might best be duplicated by talking to oneself while leaning into a steel drum.
While the ear trumpet in the museum’s collection looks simple, it is actually constructed of eight separate pieces of tin soldered together. The overall length is 21.5 inches. The bell opening is 5.5 inches. With the invention of the first electronic hearing aid around 1900 (the result of Alexander Graham Bell’s experiments in developing the telephone) followed closely by further refinements in hearing aid methods, the ear trumpet probably passed out of common use by the 1920s.
The ear trumpet in the museum originally was owned by Mary E. Stader. It was donated to the museum by her grand-daughter, Mrs. C.E. Rippetoe in 1961. This unique device may be seen in a display case devoted to medical items on the lower floor of the museum