Kennan received from the age of six piano lessons, soon followed by lessons in organ and flute. He studied at the University of Michigan, then at the Eastman School of Music, where he earned a degree in composition and music theory music. In 1936 he was awarded the prestigious Prix de Rome, which allowed him a three-year period of study in Rome. His teacher there was Ildebrando Pizzetti. He then taught temporarily at Kent State University.
Only interrupted by military service and a shorter professor at the Ohio State University in the 1950s, Kennan was over 40 years as a member of the faculty of the University of Texas at Austin. In 1983 he became Professor Emeritus.
Kennan's half-brother was the historian and diplomat George F. Kennan.
In Kennan's work directory to find orchestral works, chamber music and vocal compositions. One of his best known works Night Soliloquy for Flute and Strings ( 1936), which took conductors such as Toscanini, Ormandy Stokowski or the program. Were often mentioned, for example, his Sonata for Trumpet and Piano, the Three Pieces for Orchestra and the Three Piano Preludes.
After 1956, Kennan wrote and barely moved the focus on his educational work. His two books, " The Technique of Orchestration " (1952) and " Counterpoint " (1959) experienced multiple reissues.