The Difference between a Tone and a Semitone
1 tone = 2 semitones
1 half tone = 1 semitone
There are 2 kinds of semitones:
- Diatonic Semitones - move a semitone and change the alphabetical name
- Chromatic Semitones - move a semitone and retain the alphabetical name
Double sharps or ## can also be written as x therefore F## = Fx
Double flats are written as double flats... no change, e.g., A♭♭ is A♭♭
Some of these examples are very tricky:
Example 1. A♭ → B♭♭ (Normally A♭ → A )
You can't go from A♭ → A because you have to change the name (diatonic)
A = B♭♭, and therefore A♭ → A becomes A♭ → B♭♭... presto!
Example 2. F## → G#: (Normally G - G#)
You can't go from G → G# because you have to change the name (diatonic)
F## = G, and therefore G → G# becomes F## → G#
Example 1. E♭♭ → E♭ (Normally D → E♭)
You can't go from D - E♭ because you have to keep the same name (chromatic)
D = E♭♭, and therefore D → E♭ becomes E♭♭→ E♭
Example 2. F# → F## (Normally F# → G )
You can't go from F# → G because you have to keep the same name (chromatic)
G = F##, and therefore F# → G becomes F# → F##
I have included accidentals in this segment because they move notes up or down a tone or semitone depending on which one is used.
- An accidental is a symbol placed in front of a note to make it sharp (#), flat (♭), or natural (♮)
- # Sharp: A sharp placed in front of a note raises it one semitone.
- ♭ Flat: A flat placed in front of a note lowers it one semitone.
- ♮ Natural: A natural placed in front of a note restores it to its original pitch position after it has been sharpened or flattened by an accidental.
- x Double Sharp: A double sharp raises a note 1 whole tone.
- ♭♭ Double Flat: A double flat lowers a note 1 whole tone.
- An accidental occurs within a piece of music in addition to the key signature.
- An accidental lasts for the duration of a bar unless contradicted before the end of the bar.
- Accidentals do not affect the same note on a different octave, unless it is indicated by a key signature.
- Accidentals are not repeated on tied notes unless the tie goes from line to line or page to page.
- Accidentals are not repeated for repeated notes unless one or more different pitches(or rests) intervene.
- An accidental must be placed before the note with the line or space bisecting the sharp(#), flat(♭), or natural.
An accidental remains in effect for the remainder of the measure.
An accidental applies to a single octave only.
Double Sharp and Double Flat
Whenever you play a piece of music, take notice of the things you see on the music sheet. Have a look at the clef signs, the time signature, accidentals, rests, etc. They are all indicators to show you how the piece is to be played. Like any subject, whether it is a language or science, there are criteria and certain rules you need to follow. If you remember the rules and more importantly understand them, learning becomes a 'breeze'.
More on Tones, Semitones, and Accidentals...
I have included the following video by musictheoryguy, just in case you need further help in understanding tones, semitones, and accidentals... great viewing.