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.
John Bardeen
Bardeen was honored on a March 6, 2008, United States postage stamp as part of the "American Scientists" series designed by artist Victor Stabin. The $0.41 stamp was unveiled in a ceremony at the University of Illinois. His citation reads: "Theoretical physicist John Bardeen (1908–1991) shared the Nobel Prize in Physics twice — in 1956, as co-inventor of the transistor and in 1972, for the explanation of superconductivity. The transistor paved the way for all modern electronics, from computers to microchips. Diverse applications of superconductivity include infrared sensors and medical imaging systems." The other scientists on the "American Scientists" sheet include biochemist Gerty Cori, chemist Linus Pauling and astronomer Edwin Hubble.