Dennis studied composition with Marie Martin, Frederic Coulter, Salvatore Martirano, and Wlodzimierz Kotonski; he studied electronics, computer techniques, and programming with Gordon Mumma and Herbert Brün. A Fulbright Scholar, Rome Prize and Guggenheim Fellow, Eberhard received numerous grants and awards. These included a Martha Baird Rockefeller Grant, two grants from the National Endowment for the Arts (NEA), seven Individual Artist Awards from the Ohio Arts Council, and three McDowell Colony residency grants. He was also the recipient of the Cleveland Arts Prize, the 1990 Award of Achievement in Classical Music from Northern Ohio Live Magazine, and the 1993 Distinguished Alumnus Award from Kent State University.

Eberhard's work has been performed throughout the United States, Europe, Australia, and South America, appearing at such prestigious venues as the Fromm Festival of Contemporary Music at Tanglewood, Gaudeamus Music Week in Holland, the "Warsaw Autumn" International Festival of Contemporary Music in Poland, and the concert series at the 92nd Street Y in New York City. Many important ensembles including The Cleveland Orchestra, the Cincinnati Symphony Orchestra, the São Paulo State Symphony Orchestra, the RAI Orchestra of Rome, Dutch Radio Chamber Orchestra, and the State Academic Cappella Symphony Orchestra of St. Petersburg, have performed his music. His music is recorded by NAXOS.

While continuing his career as a composer, Eberhard became an advocate for people with disabilities. He served as Director of Transitional Education Services and Peer Support Specialist at Services for Independent Living where he worked to empower people with disabilities to become self-directed and in-control of their lives. Eberhard also wrote extensively on disability and, as co-founder and vice president of the Lake County Advocacy Task Force, he continued to work on behalf of people with disabilities until his death in 2005.