Abstract
Blues is a form of American root music, and it has been a major influence on later popular music. It is composed by Blues scale, and uses grace notes to embellish the melody. It is also formed by the dominant 7th chords as the basis. In this paper, we describe an HMM (Hidden Markov Model) -based variation system for producing Blues style music. To let the varied melody satisfy the characteristics of the Blues music, there are three varying steps implemented in the system, including: Blues scale transformation, grace notes insertion, and dominant 7th chords accompaniment. The experiment results show that the degree of Blues style increases as the proceeding of the three varying steps, and there are 74 percent of experimenters in average considering the varied melody as the Blues style music. To the best of our knowledge, this is the first variation system for producing Blues style music, and the results are satisfactory.