There are two ways to write a diatonic scale on the stave.
With a key signature
Without a key signature
With a key signature you establish the accidentals at the start of the stave. Without a key signature you define each accidental as it is played.
The key
In the key of G, F# is normal. The key signature of G is appropriate.
To write a melody without a key signature you define each accidental as it is played. Scroll down to the next illustration. Press the midi buttons to hear each illustration. Can you hear the difference? No. Can you see the difference? Yes.
The melody with a key signature looks cleaner and more informative. The key signature tells the musician to expect F# and it tells the musician which key the music is in.
We can distort the look of the melody by changing the key signature. This melody sounds the same as the two above but it looks awful. It is still in the key of G. The key signature has changed to Ab.
Now shift each note up a semitone. What have we done? We have changed the key. We have changed the sound. The melody is now in the key of Ab A melody in the key of Ab looks right in the Ab key signature.
Accidentals on the stave
In the key of D, F# and C# are expected. When the key signature is D each unaltered F is F# and each unaltered C is C#.
To override the key signature you place an accidental at the note-head.
The accidental in front of the note-head holds true:
- for the line or space it is on
- until the next barline
- or until it is changed by another accidental
Take a close look at this example. The barline is the vertical line cutting through the stave at regular intervals. The barline measures the pulse.
The music starts on AB The second note is A natural. Remember the rule: For the line or space it is on. The higher A is natural until we make it flat.
The 4th and 8th notes are F#. We must repeat the sharp accidental to repeat F# because high F# is on a different part of the stave to low F#.
The last note before the first barline is AB We do not put a flat in front of the note head. Trace the AB space from the first note on the stave to this note. Remember the rule: For the line or space it is on until the next barline.
We had F# in the first bar. We want F natural in the second bar. This is easy to achieve. We do nothing. F# in the first bar lost its power at the barline.
Clarity
How do we define success? When a professional musician can play your music comfortably at first sight.
How to we achieve success? We clarify ambiguous accidentals. A correctly written note may have no accidental at the note-head but still cause confusion. You don’t want rehearsal time wasted on such questions as “Is that natural or sharp?” Arguments may spark along the lines of … “Musically it could be …” and “Yes, but I think that’s a printer’s error.” If half the musicians play C natural and half play C# together you are in trouble.
Study this example. Is the first note of bar 4 C natural or C#?
If you mean C# write C#.
If you mean C natural put a natural accidental in brackets in front of the note head. By putting the accidental in brackets you are confirming the key signature.
The key signature
tells the musician which key the music is written in and which accidentals (flat, natural, sharp) are normal to the stave.
Standard accidentals at the note head
tell the musician that this note is altered from the key signature or altered again in the bar. Do not go mad putting accidentals in front of every note head. Learn the rules. A well-written melody is one a professional can sight read perfectly at first glance. Aim to please the professional musician.
Accidentals in brackets at the note head
confirm the key signature where ambiguity may otherwise arise. Don’t bracket accidentals which shouldn’t have brackets. The accidental in brackets is always true to the key signature. It is a reminder of the key signature, never contrary to it.