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.
Rufus P. Turner
Turner was involved with creating the 1N34A germanium diode at Sylvania in the 1940s. He began experimenting with germanium transistors soon after their invention in 1947. In 1949, before transistors were commercially available, he published the popular article "Build a Transistor", considered a "benchmark publication" in amateur radio. In January 1950, after commercial units were released, he published "A Crystal Receiver with Transistor Amplifier" in "Radio and Television News", along with plans for a three-transistor radio circuit. These plans – printed four years before the Regency TR-1 (the first commercial transistor radio) – were the first time most amateur radio operators were introduced to transistors as viable radio components. He continued development of his pocket-size radios as superior transistors became available, culminating in the 'widely read' "Transistor Portable with a "Punch"", an 'ambitious' four-transistor non-superheterodyne AM radio published in "Popular Electronics" in 1956.