When he saw the Beatles on The Ed Sullivan Show at the age of seven, however, he developed an interest in the guitar and eventually began playing blues music. His taste expanded into jazz in high school, and he went to the University of South Dakota to study music. He transferred to the Berklee College of Music in Boston in 1976. After graduating, he studied privately with Jerry Bergonzi and Charlie Banacos, focusing on the relationship between jazz and classical music. He taught at the New England Conservatory, Dartmouth College, and Berklee, then moved to New York and began to teach at Princeton University and New York University, and to write music instruction books.

As a performer, Arnold became involved with other musicians who shared his interests in classically influenced controlled improvisation. In the 1990s, he formed the group Act of Finding with Tom Buckner, Tom Hamilton, and Ratzo B. Harris to pursue these interests. In addition, his group Spooky Actions at a Distance was formed to play classical music of such composers as Webern, Schoenberg, Bartók, and Debussy, arranged to allow for improvisation. In 1995, Arnold released his first album as a leader, Blue Eleven, which employed improvisation within a 12-tone scale. He followed it with A Few Dozen in 2000 and Give 'Em Some in 2002. But, recognizing the popular limits of his musical approach, Arnold was careful to maintain his academic and literary career. As he told an interviewer in December 1998, "I have never been that socially ambitious, and I am lucky that I can make my living as a music teacher, so I can concentrate on staying true to my goals." ~ William Ruhlmann