There are infinitely many musical notes, just like there are infinitely many colours. That matters if you are designing a new digital musical instrument. You have a lot more choice than on a piano!
Octaves
Most Western music is divided equally into groups of 12 notes (‘octaves’) that musicians use. The gap between any two notes sounds the same. This is known as equal temperament tuning.
Activity: Play the 12 notes
You can play the 12 notes of an octave on the online piano https://bit.ly/pianoCS4FN. Play Middle C (marked with a red dot), then press each key in turn including the black keys. Play 12 notes and you have played the 12 notes of an octave.
Music as colour
The rainbow picture shows there are many colours to pick from not just red, orange, yellow… A set of crayons would be enormous if it included every possible colour! Instead you get a selection just as in the picture: we picked 3 colours equally spaced apart: red, yellow and blue. Western music does the same thing with sound, picking 12 notes that sound equally spaced.
There are lots of other notes that you could sing within an octave. Traditional music often uses different sets of notes. The Arabic system divides an octave into 24 notes, for example. They have more ‘sound crayons’ to play with! You could even start singing on a low note and continually raise your pitch until you reached the higher note, like sweeping through every colour in a musical rainbow.
If you sing a note, then sing the same note but an octave higher (eg Middle C then the next highest C), your vocal cords are now vibrating twice as fast! The frequency of the top note is twice as high as the lower one. Your vocal cords doubled their speed.
By Jo Brodie and Paul Curzon, Queen Mary University of London
More on…
We have LOTS of articles about music, audio and computer science. Have a look in these themed portals for more:
- Music and AI
- Music, Digital or Not
- Audio Engineering
- Read more about Music and AI in our mini-magazine “A Bit of CS4FN” issue 6
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