Mr. Getty's music is not going to strike terror into the heart of Aaron Copland or Pierre Boulez. It is frankly, even defiantly, derivative music, stemming from Mendelssohn, Schumann, Verdi, and Puccini. Some might call it the work of a sensitive amateur. But Mr. Getty feels that he is a composer who can pick up the threads of what he calls ''the grand tradition.'' More and more composers, he claims, are looping back.

Perhaps he is right. The last decade has indeed seen a headlong flight from strict serialism. But Mr. Getty's music leans so far in the opposite direction that professional composers will probably refuse to take him seriously. Audiences, on the other hand, seem to respond to Mr. Getty's simple music and open lyricism. He received a very good press on the West Coast for his most ambitious work, Plump Jack, and critics around the country have had good words to say about his Dickinson cycle. Some well-known artists are beginning to look at that piece, and it has been programmed by several singers, including Mignon Dunn and Judith Blegen. 

Plump Jack, with its elements of Puccini and Verdi, might be described as contemporary in the sense that the vocal line is largely recitative, with the orchestra carrying the melodies and commenting on the action.