"[Loredana] Lippernini also argues that [Italian] rap music could be said to have dual origins in the oral traditions of the griots of Africa and in the recitativo used in early Italian operas in Florence in the sixteenth century, with their 'imitar con canto chi parla' (imitating in song a person speaking). In his book Opera, Edward J. Dent traces the origins of Italian opera, which throughout the seventeenth century was a form of recited music drama in which vocal declamation was made to music which was focused around a figured bass line: 'what the promoters aimed at more than anything else was the declamation of the words. If there was anything like a complicated orchestral accompaniment, the words would not be heard' (1949, p. 102). This led to the development of lyrical refrains to break the monotony of the declamation, and these in turn evolved into arias. As a way of keeping the narrative in opera moving, early opera developed recitativo secco (dry recitative), which was 'accompanied merely by a bass viol holding the bass in slow notes, and a harpsichord filling up the minimum of harmony' (ibid., p. 103). The musicality of opera required the words to be metrical, and one had to be able to beat time to the required music, which meant that the speech patterns were both melodic and rhythmical. (The Onda Rossa Posse's first EP was entitled Batti il tuo tempo -- Beat Your Own Time.) With the development of commercial opera in Venice, songs and dances were interpolated into operas, along with 'the interplay between voice and instruments in the course of a song' (ibid., p. 104). By the time of Gluck, audiences had grown weary of the single voice in operas, and the duet form was borrowed from comic opera, which enabled two characters to 'quarrel and call each other names' (ibid., p. 105). This device was developed into "concerted finales" in which several characters could engage in conversation. One of the features of Italian rap is what is referred to as the microfono rotante (rotating microphone) in which a large number of rappers swap verses of a song. This multiplicity of voices, in which random elements are often incorporated, is sometimes extended into microfono aperto (open microphone), when audience members are invited to improvise participation in the rap. As Sud Sound System has explained: 'The microphone is open to anybody: in our concerts there is no difference between who's on stage and who's on the dance floor' (Lipperini, p.25)."
Tony Mitchell, "Questions of style: notes on Italian hip hop," Popular Music (1995) 14.3, pp. 333-348.