Dr. Soper joined the English Department faculty in 1936, relocating from Cornell University. He was appointed theatre director in 1939, and in 1940–41 a one-year course in theatre was introduced into the English curriculum, offering the study of acting, stagecraft, play interpretation, and directing. There was, however, no adequate theatre on campus for productions. The program improvised with use of on-campus performance spaces at Ayres Hall and Tyson House and off-campus, from 1939 to 1945, in the auditorium of Tyson Junior High School. In 1945 a rental arrangement was established that allowed university plays to be staged at the Bijou Theatre.
In 1950, after the successful production of The Women, written by Clare Booth Luce, by the university and the Junior League of Knoxville, Soper planned for the summer of 1951 a series of plays that combined UT and community talent. For the summer plays, the university, the Junior League, and other community volunteers erected a tent for the plays and called it the Carousel Theatre because of its design. The summer experiment was successful, and in December 1951 the trustees approved a loan for construction of a facility designed on the basis of the Carousel tent. Carousel Theatre is the oldest arena stage in the South. Soper was also instrumental in the design and construction of the Clarence Brown Theatre.
In 1968 he became head of the Department of Speech and Theatre, when the program achieved independent status. He retired as head of the department in 1972 and continued to serve as a faculty member in the department until his retirement in 1976. He directed more than 140 plays at the university, and his original play, Once Upon a Town, which parodied political life in Knoxville during the 1950s, was one of the Carousel Theatre’s most popular and longest-running productions.
He was president of the Southern Speech Association and author of one of the most widely used public speaking textbooks, Basic Public Speaking (3rd. ed., 1963), as well as the author of numerous articles on speech, drama, and theatre. Findlay College awarded him the honorary degree of doctor of humane letters in 1962, and he was the recipient (1976) of an Alumni Outstanding Teaching Award and a Chancellor’s Citation for Extraordinary Service to the university. His contributions to the intellectual life of the university have been recognized by placement of a plaque in his honor on a faculty study.