Because audience is derived from a Latin word meaning "to hear," some experts insist that the word can properly apply only to a group of persons engaged in listening. Such purists feel that where looking (seeing) is the primary activity involved, persons comprising an audience should be called spectators. Audience is now widely and acceptably applied to listeners and viewers collectively — to persons attending a theater or concert as well as those reached by radio or television broadcasts, by books, newspapers, and magazines, and by public speakers: "The studio audience was convulsed with laughter." "Many works of art have a wide and devoted audience."
Dictionary of problem words and expressions. Harry Shaw. 1975.