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.
Morris Tanenbaum
In the meantime, Gordon Teal had moved to Texas Instruments, where he was essential to the organization of TI's research department. He also led its team of silicon transistor researchers. On April 14, 1954 he and Willis Adcock successfully tested and demonstrated the first grown-junction silicon transistor. Like Tanenbaum, they used highly purified DuPont silicon. Teal was able to bring the silicon transistor to production. He announced the results and displayed the TI transistors on May 10, 1954 at the Institute of Radio Engineers (IRE) National Conference on Airborne Electronics, in Dayton, Ohio.