Guitar Theory and Mental Mapping : Post 7

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The 12 Notes in Western Music

In western music, there are 12 named notes which are named using the first 7 letters of the alphabet.

  • A, B, C, D, E, F, G

But 7 letters doesn’t make 12 notes!

The additional notes are named using sharps and flats.

Sharps (#) & Flats (b)

The ‘#’ sign is pronounced sharp and the ‘b’ sign is pronounced flat.

Sharp can be thought of as going upwards and flat can be thought of as going downwards.

The table below shows the names of the twelve notes.

Note: Name 1: Name 2: Name 3:
1 A
2 A# Bb
3 B Cb
4 C B#
5 C# Db
6 D
7 D# Eb
8 E Fb
9 F E#
10 F# Gb
11 G
12 G# Ab

You’ll notice that most notes have more than one name.

eg. The note above A can be referred to as A# or as Bb, the note below F can be referred to as E or Fb

Later in this blog, we’ll understand the circumstances under which it is appropriate to use to each name.

Tones and Semi-tones

Each of the notes is one semi-tone apart.

eg. D# is one semi-tone above D which is one semi-tone above C#.

A Tone means 2 notes apart:

  • 2 Semi-Tones = 1 Tone

Eg: The note B is one tone above A. The note F# is one tone above E

On the guitar fretboard, 1 fret corresponds to 1 semi-tone and hence 2 frets correspond to 1 tone.


When you get to G#, the next note up is again an A. However, this A is an octave above your initial A, meaning that it is higher in pitch than your first A.

If you’re going down then when you get to A, the next note down is a G# one octave below your previous G#, meaning that it is lower in pitch than your first G#.

Since there are 12 notes in western music, the note repetition occurs after the 12th note:

  • 12 semi-tones = 1 Octave

On a guitar fretboard, this means there is repetition after 12 frets. This’ll be why (for most of you) there are double dots on your fretboard at the 12th fret and the 24th fret (if your fretboard goes that high).

Check out an example of an octave on your guitar by first playing the open 5th string of your guitar (the open A) and then playing the 12th fret on the same string. Both notes are an A, but the second one is an octave above the first.

If you’re interested in some physics behind this, if a note is an octave above another note then its value in the frequency range is double that of the first note.

For example, let’s take Concert A. Concert A is the reference note that the World tunes to.

Through the years, the actual frequency of Concert A has varied but these days we’re more or less standardised on 440 Hz.

Concert A is the note we just played – the open A string on a standard tuned guitar – 440Hz. The second note we just played – the 12th fret on the A string is the A note 12 semi-tones, 1 octave, above and has a frequency of 880Hz.

If you have an electric guitar tuner which has a frequency scale on it as well as some pretty lights, and you feel the inclination, you can figure out the frequency range of your instrument.

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