A hearing aid is an electroacoustic apparatus which typically fits in or behind the wearer's ear, and is designed to amplify and modulate sound for the wearer. Earlier devices, known as an "ear trumpet" or "ear horn", were passive funnel-like amplification cones designed to gather sound energy and direct it into the ear canal.
It is uncertain who invented the first electric hearing aid, it may have been the Akoulathon, invented in 1898 by Miller Reese Hutchinson and made and sold (1901) by the Akouphone Company of Alabama for $400.
A device called the carbon transmitter was needed in both the early telephone and the early electric hearing aid. This transmitter was first commercially available in 1898 and was used to electrically amplify sound. In the 1920's, the carbon transmitter was replaced by the vacuum tube, and later by a transistor. Transistors allowed electric hearing aids to become small and efficient.
No comments:
Post a Comment