The music tradition associated with Easter Week celebrations is still alive in Castelsardo, in the north of Sardinia. It is performed by singers who are members of a confraternity, which the status is quite the same of a professional vocal group. This music is strongly expressive, complex and sophisticated.
One of its striking characteristics is the presence in the regular four-voice quartet of a fifth, high-pitched virtual voice which creates a unique and surprising effect. This book explores the acoustic et psychoacoustic mechanism of such arrangement while analysing the music's language and his own particular aesthetics.