Tones and Semitones
We have units of measurement of intervals in music just as we do for our common math (mm,cm,m,km).
The units of measurement of intervals in music are Tones and Semitones.
What are Tones and Semitones?
Tones (T) are also known as Whole-step (W) in music. A Tone movement simply means moving from a key twice either backward or forward.
For instance when we move from key C to key D. it’s a Whole or Tone movement because you are skipping a note C# and playing the next note which is D.
The Tone movement can either be backward or forward, hence we can either say C is a Tone interval or a whole-step from D (backward movement) or D is a Tone or a whole-step from C.
Semitone (S) or half movement is simply half of a Tone which mean that we are moving just one step from a key as you don’t skip any note.
For instance C to C# is a semitone movement.
And like we said before it can either be backward or forward. There is no ban.
Now one thing you should have in mind is that there is a common mistake that goes on with new students learning the concept of Tone and Semitone movement…
“…they start counting even when no movement is made”.
That’s too bad.
Have a look at this…
This makes you understand that as you moved to D from C, you can say a Tone movement has been made (2 semitones). From E to F is a semitone movement because there was no key in between. Just like your clock system in which 1am to 2am is an hour interval and not two hours. A movement must be made before you say Semitone.
To help you better, I will recommend you to start using the smallest unit which is semitone before converting to tone at your will.
2 semitones = 1 tone
Hope you understand that?
Also remember that these movements can even either be backward or forward movement.
I do hope you grasped all here!
***Watch Video Tutorial