Trombones often played with the three lower voices, a practice of high antiquity surviving from a time when there were soprano trombones or cornetti (Zincken, a sort of treble serpent) to play with the sopranos.
During some concerts I'll read the passage, then the soprano sings the aria.
She is also a trained soprano, and in 1998, performed twice with the All-Eastern U.S. High School Honors Chorus at Carnegie Hall.
Perry knew the song was to be used in the final scene and assumed that it would be playing as Tony Soprano was killed or arrested - something he wanted no part of.
First soprano's voices are usually a bit thinner.
