Pitch Relationships
Senior 1 · Music
Pitch Relationships
Lesson 1 of 5
20 min
Many Rwandan schools and churches have an electronic keyboard, and it is the best tool there is for seeing pitch. Every sound the keyboard can make has its own key, laid out in order from the lowest on the left to the highest on the right. In this unit you use the keyboard to measure the distances between notes, which is what the rest of music theory is built on.
The white keys carry the seven letter names A to G, repeating again and again. The black keys are arranged in groups of two and groups of three, and these groups are your map:
The C nearest the middle of the keyboard is middle C, the same middle C that sits on a ledger line between the treble and bass staves. From one C up to the next C is an octave: eight white keys counting both Cs. The two Cs sound so alike that they share a name, but the upper one is higher.
A semitone (also called a half step) is the distance from any key to the very next key, black or white, with no key in between. It is the smallest step on the keyboard. A tone (a whole step) is two semitones.
Worked example
Is D to E a tone or a semitone? Move one key at a time: D to the black key above it is one semitone, and that black key to E is a second semitone. Two semitones make a tone, so D to E is a tone.
Look for the places where two white keys have no black key between them. There are only two in each octave: E–F and B–C. These are the only white-key semitones. Every other pair of neighbouring white keys has a black key between them, so they are a tone apart.
On the staff every step from a line to the next space looks the same size, but it is not always the same distance in sound. The staff shows letter names; it takes the keyboard to show which steps are tones and which are semitones.
Worked example
How many semitones are there from C up to E? Count the keys after C: C♯ (1), D (2), D♯ (3), E (4). So C to E is 4 semitones, which is 2 tones. From E up to G: F (1), F♯ (2), G (3), so E to G is 3 semitones, even though both look like the same-sized skip on the staff.
An octave contains 12 semitones: 7 white keys and 5 black keys from one C up to, but not including, the next C.
Tip
Count the keys, not the white keys. To measure a distance, count every key you move onto, black or white; each move is one semitone. And remember the two gaps with no black key: E–F and B–C are semitones.
Try each question first, then check the worked solution underneath.
How do you find F on a keyboard?
Solution: It is the white key just to the left of a group of three black keys.
Is A to B a tone or a semitone?
Solution: A tone: there is a black key between A and B, so the distance is two semitones.
Name the white key that is one semitone above B.
Solution: C. There is no black key between B and C.
How many semitones are there from F up to A?
Solution: 4: F♯ (1), G (2), G♯ (3), A (4). That is two tones.
How many semitones make one octave?
Solution: 12. From C, count C♯ D D♯ E F F♯ G G♯ A A♯ B C: twelve moves.
Remember
Sources and credits
The lesson text, the keyboard and staff diagrams, the worked examples and the practice were written by Ganzaa.
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
