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.
Dmitri Z. Garbuzov
The 1970 demonstration of the first room-temperature diode laser crowned years of scientific and technological research developments involving optical semiconductors. These accomplishments parallel, but lag, the microelectronics revolution that started with the transistor, first demonstrated in 1947 (leading to the displacement of vacuum tube electronics in the marketplace). Although the laser had already been invented by Charles Hard Townes and Arthur Leonard Schawlow, separately by Gordon Gould, and separately in the Soviet Union by Aleksandr Prokhorov, there was no practical laser "chip" which would make the laser a commodity, one that today is displacing more inefficient lasers (those based on gas discharge or flashlamp designs) in the consumer, industrial, medical, and government marketplaces.