The interval is the basic "word" in the language of music. Stringing these "words" together gives small pieces of melody or chords. And so it builds into the bigger structure of a tune, a verse, a chorus, and so on to the final composition or improvisation.
The ultimate goal of learning intervals is that they are one of the musical tools that allow you to manipulate the emotional responses of your listeners, lifting them up, dropping them down. When combined with strong phrasing, and feel, you have a lot of power at your finger tips, literally. In the next article, I'll explore some of these aspects. Pitch names are unnecessary for the majority of this discussion (today and later), which is a big hint to how widely useful a knowledge of intervals is, when applied.
So today we use intervals for the purpose of speeding up the process of gaining familiarity with the guitar neck. The main goal of this article is to provide you with a set of visual shapes (interval shapes formed by your fingers, and seeable in your mind's eye) to add to your guitar toolbox. These shapes help you reinforce your knowledge of chords and scales, and they generally help you navigate the fretboard without too much pain. Their sounds can be recognised with ear training, but this is not needed initially.
So, with the background set, let's get going...
Pitch, Octave, SemitoneTo give a reasonable understanding of what an interval is we have to take a short detour through the world of pitch, octave, and semitone.
Any pitch has a particular (fundamental) frequency of sound. The higher the frequency value, the higher the pitch we hear (recording engineers talk about bass, low-mid, high-mid, high (treble) frequency ranges. The instrument build and the way we play cause other frequencies to get added in, creating the sound of a "guitar" or "violin" playing the same particular fundamental. When you dampen the string (or when you change the tone control, volume...), these additional frequencies get changed, but the fundamental is still the main frequency we perceive.
Guitar is constructed so that the fundamental frequency of a pitch at some (any) fret (and think of the open string as fret 0, where fret 0 is the nut), and of the pitch produced at its adjacent fret on the SAME string are always related by a mathematical formula... the higher pitch is always 1.059 times the frequency of the lower pitch, and the (frequencies of) two pitches are said to be "a SEMITONE" apart. With pitches three semitones apart, the upper pitch is 1.059 * 1.059 * 1.059 * lower pitch. If two pitches are 12 semitones apart, the upper pitch is 1.059 * 1.059 * 1.059 * ... (12 occurrences of 1.059 multiplied together), which equals 2. When one pitch is double the other, the upper pitch is said to be an octave above the lower pitch, or they are an octave apart.
Forget the maths!The maths/physics doesn't matter to us as musicians, but we've grabbed the term SEMITONE to talk about the relationship between two pitches, and we say stuff like "these two pitches are 3 semitones apart", or "these two pitches are zero semitones apart (identical)."
The intervalLastly, musicians also use the term INTERVAL as a synonym, meaning two pitches some number of semitones apart. We may say "play an interval of 3 semitones, starting off the pitch E," or "play an interval of 3 semitones anywhere" ... so here you'd randomly choose a fret, and then play either 3 frets higher or 3 frets lower on that same string. If we said "play an interval of 3 semitones above an arbitrary pitch," then you'd randomly choose a fret, and then play 3 frets higher.
Notice that an interval always involves TWO pitches, no more, no less.
Interval namesBut then the theory boys thought "Nah ... this is to easy; let's confuse everyone." So, they invented terms like "minor third," "diminished fifth." So, for example, "diminished fifth" is Chinese for "6 semitones," and "minor third" is Swahili for "3 semitones." In general, we then have this vocabulary of INTERVAL NAMES. However, since there are only a handful of these names, its no big deal to learn them. I'll come back to this.
The brain's perception of intervalsNow to the crux of the matter. The brain, via the ear, isn't fooled or interested by these strange names, or by pitch names (E, F# etc) ... instead it literally detects the frequency relationship between pitches.
If we have two intervals that differ in the number of semitones involved, we say they are different intervals ... the brain perceives these have different sound character, regardless which pitches are involved. Whereas if we have two intervals both with the same number of semitones, they have the same sound character, regardless of which pitches are involved. So, the brain perceives the specific character of 4 semitones, its flavour of sound, if I played fret 1 followed by fret 5, or fret 7 followed by fret 11, and so on.
Finally, as noted above, because of the way the guitar is tuned, there are a few possibilities (not many) for how to physically create the SAME interval, by playing both pitches on one string, or by using two strings (not necessarily adjacent). The limitation comes down to hand stretch.
With this background out the way, here are the shapes ... they are incredibly easy to learn. You'll immediately start seeing them in scale and chord shapes you know.
Here are the important ones ... "5 ST" drawn between two strings mean these strings are tuned 5 semitones apart (so, E and A, A and D, D and G, and B and E). "4 ST" only applies to G and B. Say with E and A being 5 semitones apart, this means that pitches played on the SAME fret on both strings (which is simply a vertical line shape) are 5 semitones apart. Therefore, an interval of 3 semitones must be playable by moving down 2 semitones (5 - 2 = 3) on the upper string of the pair. Hence the red shape. This shape applies anywhere on all string pairs tuned 5 semitones apart. On the G and B strings, a vertical line here forms 4 semitones, therefore an interval of 3 semitones must be playable by moving down 1 semitone (4 - 1 = 3), and hence the green shape.
This first shape of 3 semitones is named "minor third" or written as "b3" in scale formulae. So, if you have minor pentatonic starting off 8th fret on D string, the b3 is found on the 11th fret on the same string, or on the 6th fret of the G string (using the red shape, where the lower red pitch is on the D string).
So, one method is to "find start note, then use interval shape, to find other pitch in the interval." If you're playing G minor scale (1, 2, b3, 4, 5, b6, b7) rooted off G, then you can find any G (e.g. 12th fret on G string) and use the interval shape (green this time) starting off this fret on the G string, so you'd play the 11th fret on the B string.
Here is 4 semitones (major 3rd)
The next interval is called a "perfect 4th" written simply as "4."
Note in the next shape, we just have to adjust the vertical line by 2 frets to get (5 + 2 = ) 7 semitones. On the G,B pair, we have to adjust by 3 frets, as that vertical line forms an interval of 4 semitones (4 + 3 = 7).
This interval of 7 semitones is called a "perfect 5th," or "5th" for short. Written simply as "5."
Here, we build the same interval of 7 semitones using 3 strings. Note that if we start on the bass E string and move vertically to the next string, we get 5 semitones (as above). Move vertically again to the next string (we're on the D string), this is another 5 semitones higher again. We make an interval of 10 semitones in a vertical line from E to D string. So, adjust that back by 3 frets, 3 semitones, to get (10 - 3 = ) 7 semitones.
Here are the only ways to play an octave "to the right" of the lower pitch.
Here are the only ways to play an octave to the left.
You can use these octave shapes to locate the same pitch name all over the neck (duplicate pitches or pitches that are related by octave).
Here are the octave shapes chained together. They break a 12 fret block of the neck into 5 regions.
Here is an example chord. See if you can recognise some intervals in it...
I hope this gets you going. Practice these by choosing one or two intervals, draw their shapes on paper, then have guitar in hand and form the shapes and look at your fingers. Shut your eyes, and feel that shape in your hand. Then try moving the shape (slide it). Then try playing it, take your hand off, and put it down somewhere else (all with eyes shut). Watch out for how the shape changes when on the G and B string pair. I'd only do 5 - 10 minutes on the guitar. Come back to it again 30 minutes later. Then a few hours later. You'll learn these very quickly.
As importantly, listen to the sound quality, and get a mate to practice with you, if you can, or use an ear training program. If you've recognised the sound quality, you then know the interval shape to apply from that start note.