C clefs and reading in every clef – free music theory course

Besides the treble and bass clefs there is a third family: the C clefs. The sign, shaped like a stylised "B" (𝄡), points with its centre to one line: that line is middle C.

The two C clefs still in common use

Alto clef (C clef on line 3): middle C is on the middle line. It is the clef of the viola and often of the viola da gamba.
Tenor clef (C clef on line 4): middle C is on line 4. Used by the cello, bassoon and trombone in their upper register, to avoid ledger lines above the bass staff.

The same melody in the alto clef…

M:4/4
L:1/4
K:C clef=alto
C D E C | C D E C | E F G2 |]

… and in the tenor clef

M:4/4
L:1/4
K:C clef=tenor
C D E C | C D E C | E F G2 |]

This is the opening of Frère Jacques ("Are You Sleeping?") at the same sounding pitch; only the position on the staff changes.

The "seven clefs" of French solfège

French conservatoire training drills reading in seven clefs: treble (G on line 2), bass (F on line 4), baritone (F on line 3), and C clefs on lines 1, 2, 3 and 4 (sometimes also the "French violin clef", G on line 1, from the 18th century). The soprano (C on line 1) and mezzo-soprano (C on line 2) clefs were once used for voices in the scores of Bach or Mozart.

Why bother today? To read orchestral scores and early editions, to accompany a violist or cellist, and to transpose at sight: a musician who knows all the clefs can read a B♭ clarinet or F horn part simply by imagining a different clef.

Reading method: find the middle-C line (marked by the centre of the clef), then read by intervals from that C. In the alto clef, middle line = C4, the space above = D4, line 4 = E4, and so on.

Don't confuse: in any C clef the C indicated is always middle C (C4), never another C.