Requiem per una veu perduda (Requiem for a lost voice in Catalan) is a piece for mezzo-soprano with on-stage effects processing and recorded electroacoustic material. The electroacoustic material consists mainly of synthesised vocal sounds and the pitches for the mezzo-soprano part were defined based upon the functioning of the speech synthesis methods used. This paper outlines the basics of one of the speech synthesis methods used to compose the piece and introduces the scheme for the definition of the pitch material for the singing. The relationship between the speech synthesis methods and the pitch material establishes the structural foundations of the piece.