History of hearing aids
The development of transistors in 1948 by Bell Laboratories led to major improvements to the hearing aid. The transistor was invented by John Bardeen, Walter Brattain, and William Shockley. Transistors were created to replace vacuum tubes; they were small, required less battery power and had less distortion and heat than their predecessor. These vacuum tubes were typically hot and fragile, so the transistor was the ideal replacement.The 1952 Sonotone 1010 used a transistor stage along with vacuum tubes, to extend battery life. The size of these transistors led to developments in miniature, carbon microphones. These microphones could be mounted on various items, even eyeglasses. In 1951, Raytheon manufactured the transistor and was one of the first companies to mass-produce transistors to throughout America. Raytheon realized that their hearing aid only lasted short-term and began to sell the vacuum-tube hearing aids again along with transistor hearing aids.
Invention of the integrated circuit
In 1952, Jewell James Ebers from Bell Labs developed a prototype solid-state analog of thyratron – a four-layer transistor, or thyristor. William Shockley simplified its design to a two-terminal "four-layer diode" (Shockley diode) and attempted its industrial production. Shockley hoped that the new device will replace the polarized relay in telephone exchanges; however, the reliability of Shockley diodes was unacceptably low, and his company went into decline.