Unfortunately Telsa's high school career was cut short due to a bout with Cholera that nearly killed him. It was during his time in bed that his father told him that he would allow Nikola to go to study electrical engineering at the prestigious Polytechnic Institute in Graz, Austria. Nikola was overjoyed to hear the news and after regaining his health he left for Austria at the age of 19.
It was at the institute that Tesla discovered a problem that would become his obsession for years: alternating currents. During one of his classes a professor was demonstrating a piece of electrical equipment that worked on DC (direct current) power and required a commutator to change the direction of the current. Tesla thought that if he could come up with a way to make the current itself alternate, the commutator would be useless. He remarked to the professor about his plans only to be ridiculed. The judgement didn't phase Nikola one bit and he thought about the problem day and night, sleeping an average of only four hours. The solution still eluded him after leaving Austria to work for the American Telephone and Telegraph company in Budapest. During his time in Budapest he came up with the idea for the loudspeaker, and in what would become Tesla's fashion, he failed to patent the idea.
Telsa's propensity for illness also followed him to Budapest. There he was stricken by a very mysterious illness. Tesla had always had sharp senses, but one day they all seemed to go into overdrive to the point where he was incapable of performing even menial tasks. The sound of a sound of a pocket watch, even several rooms away, became deafening to him. He installed rubber cushions on the feet of his bed to decrease vibrations from people walking nearby, which shook him terribly. Years later he claimed to be able to hear thunder from hundreds of miles away. At the same time Tesla began to manifest symptoms of obsessive-complusive disorder.