In Western music we have a total of 12 pitches/tones/notes at our disposal. The distance between each note when played in sequence is a semitone. We call this the Chromatic Scale:
A A#/Bb B C C#/Db D D#/Eb E F F#/Gb G G#/Ab
The Chromatic Scale to a musician is the same as a paint palette to painter.
Once we arrive at ‘G#/Ab’ we get back to ‘A’ again, only this time it’s an octave higher (the note pitch is perceived higher, we'll get on to this in a bit) and the cycle continues.
Here is a diagram of a where the notes are located on a piano:
If we look at the first note on the left C and follow along until we get to the next C note we can find all twelve pitches/notes are in between. We can also see how the 12 notes continue to cycle as we move along the piano.
Key points: I. All notes on the white keys we call NATURAL
II. All notes on black keys we call ENHARMONICS
III. # means SHARP IV. b means FLAT
You may be wondering why the note letters repeat themselves. Whilst the letters are the same, they actually sound different. The 'C' on the left has a percieved lower pitch than the preceding 'C'.
To understand why notes repeat in our system of tuning it is helpful to learn about some of the fundamental physics of sound. Here is a a diagram of a simple sound wave:
The higher the air pressure the louder the sound, we call this amplitude - The bigger the stone you throw in the pond, the bigger the wave.
One wave cycle is when the peak and trough meet the line in the centre. The number of peaks and troughs over time is referred to as the wave frequency. Have I lost you yet yet? Keeping reading.
Musicians refer to the frequency of a wave as a pitch/note. The lower the frequency of wave cycles over time, the lower the note. The higher the frequency of waves cycles over time, thehigher the note.
Frequency is measured in Hertz (Hz) and defines how many wave cycles there are per second. Let’s look at a piano diagram again:
The note middle C generates sound waves at 261.6 Hz, the highest C on the diagram is 523.2 Hz. Now if you are good with math you may have noticed that 261.6 x 2 = 523.2. So we can see that repeating notes are multiples of each other. The high C is double the frequency of Middle C. I hope that makes sense.
Technically speaking there are more notes in the natural world than our ears can even perceive, but in our Western culture we only use twelve notes due to our system of tuning called Equal Temperament which, among other things, sets Western music apart from Eastern. This tuning was something developed throughout many years and involves some complex mathematical equations related to the physics of sound.
In a nutshell this simply means that instead of tuning an instrument to play in one particular key (like many eastern instruments) we can utilise 12 keys and modulate freely between them without having to retune our instruments when we want to play in different keys. If you are particularly interested in the physics of sound research the topic of the Harmonic Series.
*We call the notes C G E F etc, because could you imagine how confusing it would be if your band mate said “lets play in the key of 261.6 Hz!”.*
I hope you have found this useful, let me know in the comments.