Musical expression in automated composition of melodies

Abstract

<p>Music composed by computers has always been lacking in "musical" qualities: mood, emotional expression and a sense of purposefulness or goal. A musical expert system, called EMOTER, is the first attempt to address these important musical aspects. EMOTER receives as input a list of moods (e.g., happy, lively) and generates melodic passages intended to evoke those moods in an organized, coherent fashion. EMOTER composes the basic units of music called phrases.</p> <p> The program uses the mood-specification from a theory due to Deryck Cooke to derive a few motifs (very primitive melodic material) exemplifying the moods and computes a number of musical attributes to guide its compositional choices. A theory of emotion due to Leonard Meyer further helps plan the phrase. The theory states that an emotional response is stimulated in a listener when expectations about the progression of the music are first established and then inhibited (with the understanding that the expectations will eventually be fulfilled). A melodic passage is composed using the selected motifs, attributes and emotional theory to create a "skeletal" phrase. This is embellished and developed (also using the attributes and theory) to flesh-out the bare melodic material into a passage that embodies the musical characteristics of the mood-specification.</p> <p> Results with EMOTER are excellent. Many musical phrases comparable to music of normal composers are generated from a single mood-specification. More theory is needed, however, before the full complexities of human-composed music are sufficiently captured in code for EMOTER to pass a Turing test in music composition.</p>