Intervals
This bit is all about 'INTERVALS' and is probably not of any use to you at all unless you really want to know about the deep down dirty details of musical theory.
What is an Interval?
An Interval (cosmically speaking) is a measure of distance between two notes. The term 'distance' (in this case) refers to musical distance (i.e. pitch). Unfortunately, it's not that simple: To identify an Interval by name we must know its 'NUMERICAL SIZE' and 'QUALITY'.
The Numerical Size of Intervals
The Numerical Size of an Interval can be calculated by counting the number of notes in it (including the first and last notes). For example, from C to E we form a 3rd (C-1, D-2, E-3), from C to B we form a 7th (C-1, D-2, E-3, F-4, G-5, A-6, B-7). BUT, not all Intervals of the same Numerical Size have the same name. For this we need to calculate the Quality of the Interval by counting the exact number of Semi-tones therein (remember that a Semi-tone is just the distance between ANY two keys - black or white - on a keyboard).
Interval Quality?
By using the keyboard again, we can see that Intervals of the same Numerical Size can have a different number of Semi-tones. For example, the 2nd between C and D has two Semi-tones (which is also called a Tone, remember?), while the 2nd between B and C only has one Semi-tone. The same thing happens when you look at other Intervals: For example, the 3rd between E and G has three Semi-tones (or 1 1/2 tones), while the 3rd between F and A has four Semi-tones (or 2 Tones). This is why we also need to know the Quality of an Interval before we can know its full name.
| Semi-tones | 2nds | 3rds | 4ths | 5ths | 6ths | 7ths | Octaves |
| 0 | Diminished | ||||||
| 1 | Minor | ||||||
| 2 | Major | Diminished | |||||
| 3 | Augmented | Minor | |||||
| 4 | Major | Diminished | |||||
| 5 | Augmented | Perfect | |||||
| 6 | Augmented | Diminished | |||||
| 7 | Perfect | Diminished | |||||
| 8 | Augmented | Minor | |||||
| 9 | Major | Diminished | |||||
| 10 | Augmented | Minor | |||||
| 11 | Major | Diminished | |||||
| 12 | Augmented | Perfect | |||||
| 13 | Augmented | ||||||
Compound or Simple?
This bit is easy: 'SIMPLE INTERVALS' are smaller than one Octave, 'COMPOUND INTERVALS' are bigger than one Octave. 'Nuff said.
Melodic and Harmonic Intervals
So's this bit: A 'HARMONIC INTERVAL' has both notes played simultaneously (i.e. together at the same time), a 'MELODIC INTERVAL' has both notes played in succession (i.e. one after the other).
And finally...
Chromatic and Diatonic Semi-tones
A 'CHROMATIC SEMI-TONE' defines the distance between two notes that are a Semi-tone apart but share the same name (e.g. B-Bb), a 'DIATONIC SEMI-TONE' defines the distance between two notes that are a Semi-tone apart and have different names (e.g. F#-G).
Phew!... That's enough for now...