The alto and tenor clefs · Clefs · Music theory
The C clef marks C4 on the line at the center of the sign. On the third line it is the clef of the viola (the alto clef); on the fourth, that of the high…
The alto and tenor clefs
The C clef marks C4 on the line at the center of the sign. On the third line it is the clef of the viola (the alto clef); on the fourth, that of the high register of the cello, the bassoon and the tenor trombone (the tenor clef).
They let the middle register be written without filling the staff with ledger lines. In the alto clef the lines are F3, A3, C4, E4 and G4; in the tenor clef, D3, F3, A3, C4 and E4.
The clefs that fell out of use
Today only treble, bass, alto and tenor clefs are in daily use. But in early music the C clefs on lines 1 and 2, the F clef on line 3 and even the G clef on line 1 were normal: they let each voice fit its range. They still serve for transposing by changing the clef.
The viola is the only orchestral instrument whose usual clef is the alto. The cello, bassoon and tenor trombone use the tenor clef when they go high, to avoid ledger lines.