Clef

Picture a building where only one floor has its number painted by the lift door. If that is the fifth floor, you can work out every other floor by counting up and down. A clef does the same for the staff: it is a sign, written at the start of the staff, that gives one line its name. Once you know the name of that line, you know the name of every other line and every space.

Without a clef, a staff only says that one note is higher or lower than another. With one, every place gets a name.

One name, and the rest by counting

The most common clef is the treble clef, also called the G clef. The lower loop of its shape curls around the second line, and that is its message: the note written on the second line is a G.

Hear the passage

From there, follow the order of the names. Because lines and spaces alternate, each place up is the next name and each place down is the previous one. The space just above the second line is A, the third line is B, and the first space, just below the G, is F.

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These are the nine places of the staff in the treble clef, from the bottom up: E, F, G, A, B, C, D, E and F. The lines are E, G, B, D and F; the spaces are F, A, C and E.

Three signs that used to be letters

There are three clefs, each named after the note it marks: G, F and C. The shapes look arbitrary, but they are not. The reference line of an early staff was marked with a letter, G, F or C, and copy after copy those letters were bent into the signs used today. Lacerda tells this story for readers who know the notes as dó, ré, mi, which is why he stops to point out that the letter A is la, not do (Lacerda 1966, ch. III).

The bass clef

The bass clef, or F clef, marks F on the fourth line. The two dots after the shape sit one above and one below that line, pointing at it, and they are what is left of the letter F.

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Counting from it, the nine places of the staff become:

Hear the passage

The lines are G, B, D, F and A; the spaces are A, C, E and G. Those are different names from the treble clef's for the same places, and it is the first thing that trips up anyone learning both. The note on the second line is G in one clef and B in the other.

The treble clef serves the high sounds and some of the middle ones, roughly the right half of the piano. The bass clef serves the low sounds and the rest of the middle, the left half.

Middle C

The two clefs meet on one note: the C in the middle of the keyboard, called middle C.

Hear the notes

In the treble clef it sits on the first ledger line below the staff. In the bass clef, on the first ledger line above it. It is the same note with the same sound, written in different places because the clef is different.

Hear the passage

Hear the passage

Med uses middle C as the piece that fastens one clef to the other (Med 1996, ch. III), and it is the best anchor for reading any clef: wherever the clef is, middle C is never far away.

Why not a single clef

In theory any clef could write every sound. The trouble is reading it. A low melody written in the treble clef needs a ladder of ledger lines:

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In the bass clef the same notes fit inside the staff:

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It is the same sound. A clef is chosen so that the notes of an instrument or a voice stay on the staff rather than off it. That is exactly the reason Lacerda gives for having more than one clef (Lacerda 1966, ch. III).

The C clef

The C clef marks middle C on the line at the centre of its shape. Unlike the other two, it is still used today in more than one position.

On the third line it is the alto clef, also called the viola clef, because viola music is written in it:

Hear the passage

On the fourth line it is the tenor clef, used for the higher passages of the cello, bassoon and trombone:

Hear the passage

Both figures show the same middle C. What changes is the line on which the clef says it sits, and with it the name of every other line.

Every position

The three clefs have been written on many different lines, and each position was named after the voice that fitted it. Med gathers seven of them in the setticlavio (Med 1996, ch. IX):

Clef	Line	Name
G	2nd	treble, or violin
C	1st	soprano
C	2nd	mezzo-soprano
C	3rd	alto
C	4th	tenor
F	3rd	baritone
F	4th	bass

Lacerda lists two more, the G clef on the first line and the F clef on the fifth, and is clear that in today's practice only the G clef on the second line, the F clef on the fourth and, less often, the C clef on the third and fourth are used (Lacerda 1966, ch. III). Blatter arrives at the same four (Blatter 2007, art. 2). The others remain useful for reading early music and, as Lacerda notes, for transposing.

What comes next

With a clef, every place on the staff has a name, but the name still does not say which octave the note is in: the keyboard has several notes called C, and middle C is only one of them. That is the subject of octave designation. And the distances between neighbouring notes, which are not all the same, lead to tone and semitone.