 Alternatively, it is written on the centre line of a staff using the alto clef, or on the fourth line from the bottom, or the second line from the top, of staves using the tenor clef.In vocal music, the term "High C" (sometimes less ambiguously called "Top C") can refer to either the soprano's "C"6 (1046.502 Hz; "c"′′′ in Helmholtz notation) or the tenor's "C"5; both are written as the C two ledger lines above the treble clef but the tenor voice sings an octave lower.The term "Low C" is sometimes used in vocal music to refer to "C"2 because this is considered the divide between true basses and bass-baritones