"The antecedents for music's applications in television may be found in film and radio. Most television music (like film music) is non-diegetic: It is heard by viewers and listeners, but not on-screen performers. This "background" music is added after filming has been completed, and is used to create moods, fill spaces, provide rhythm and link the production to other cultural texts. Television music also draws on the tradition of radio, which foregrounded music through variety shows and featured performances. Variety shows were based in vaudeville and dominated the first two decades of television due to their broad appeal and low production costs. Yet music frequently was considered an afterthought during television's early years. In 1948, only 17 stations were on the air. Programming largely was produced on a local basis, and talent and material often were in short supply..."
Artículo completo en The Museum Broadcast Communications