Intervallic Structure

Below is a diagram of the guitar with intervals spread across the top E string, you should try and become familiar with intervals as it is a good way to develop your ears.

An interval of a semitone is also called a 'minor 2nd' and a tone is sometimes called a 'major 2nd'

The first thing to understand is that there are only 12 different notes in the musical language; like the alphabet by which we connect letters to construct words for communication, we do the same for the musical alphabet except with notes, and it’s the combination of notes with rhythms and the use of different timbres that produces such diversity in music. Lets start by looking at intervals and scales in practice and how they are applied to the guitar fretboard.

If you place the 1st finger on the 1st fret 1st string of the guitar, pluck that note once and proceed to move the finger up the neck of the guitar by 1 fret to pluck the next you create an interval, an interval of a semitone. All scales are built by forming intervals, the order and size of the interval is the determining factor in establishing a particular scale and therefore a particular sound.

It is important to understand the usage and construction of the major scale since it is the scale by which many others are related. The major scale is formed by creating a set number of intervals between notes when played consecutively, the intervals are:

TONE - TONE - SEMITONE - TONE - TONE - TONE - SEMITONE

Pluck the open top E string followed by placing your 1st finger on the 2nd fret same string then the 4th fret, 5th, 7th, 9th, 11th and the 12th, you can hear that it is an E major scale, observing the intervallic structure you get:

TONE - TONE - SEMITONE - TONE - TONE - TONE - SEMITONE

If you play the open top E string followed by placing your 1st finger on the 1st fret same string and move up the neck one fret at a time until you get to the 12th, you get a one octave E chromatic scale, as you can see the intervallic structure is semitone, semitone, semitone, semitone etc…

So far this might seem over simplistic, but this example is essential in helping you understand how scales work and why and ultimately how they are applied to chords for improvisational purposes.

From those examples you can see both scales have different structures and consequently different sounds, the structure of the chromatic scale being ST, ST, ST, ST, etc, and the major scale T, T, ST, T, T, T, ST.

Let us look at another example…

If you play the E Blues Scale in the same manner as the previous examples, that is to play the scale on just one string (top E string) open E, 3rd, fret 5th, 6th, 7th, 10th and 12th and observe the intervallic structure you get, minor 3rd , T, ST, ST, minor 3rd , T, yet again producing a different sounding scale as a result of the intervallic make up.

All scales are characterised by their intervallic structure; of course to play all scales solely on one string could be deemed as uneconomical, however, the reason behind momentarily playing the scales on one string is so you can see the intervallic distances between notes a little bit easier.