American research engineer Harold Stephen Black (1898-1983), following graduation from Worcester Polytechnic Institute in 1921 following graduation from Worcester Polytechnic Institute in 1921, joined Western Electric's West Street Labs in New York City, the forerunner of Bell Telephone Laboratories, when the major task confronting them was elimination of distortion.
After six years of persistence, Black conceived the principles and equations for his negative feedback amplifier in a flash commuting to work aboard the ferry. Basically, the concept that revolutionized telecommunications involved feeding systems output back to the input as a method of system control.
Negative feedback had wider applications than transcontinental and transatlantic telecommunications, including industrial, military and consumer electronics, weaponry, analog computers, and such biomechanical devices as pacemakers.
For this and other technical achievement, including pulse-code modulation, Black was awarded the Lamme Gold Medal and U. S. Department of War Certificate of Appreciation in 1921; 62 U. S. patents; 271 patents abroad; and an honorary doctorate in engineering from his alma mater.
Dr. Black worked on a negative feedback system to aid the blind and deaf from 1966 until his death.
