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
Tanenbaum made significant contributions in the fields of transistor development and semiconductor manufacturing. 
Although it was not made public at the time, he developed the first silicon transistor, demonstrating it on January 26, 1954 at Bell Labs. He also helped develop the first gas-diffused silicon transistor, which convinced Bell administrators to support the use of silicon over germanium in their transistor design. He later led a team that developed the first high-field superconducting magnets.