Intervals An intervals consists of two parts: a general name and a specific name. The general name is a number: the distance between the two notes (For example, G to A would be a 2nd, but E to B would be a 5th), and the specific name is a quality. Each quality represents a certain number of half steps to add or subtract from the major or perfect type of each interval. Note that depending on the general name, some qualities do not apply—for example, there is no such thing as a major 5th or a perfect 3rd.
Number of Half Steps | Quality for 1me, 4th, 5th, and 8ve | Quality for 2nd, 3rd, 6th, and 7th |
-3 | | Doubly Diminished |
-2 | Doubly Diminished | Diminished |
-1 | Diminished | Minor |
0 | Perfect | Major |
+1 | Augmented | Augmented |
+2 | Doubly Augmented | Doubly Augmented |
Major and Perfect The problem with this system is that it requires you to keep track of how many half steps are in the major or perfect form of each interval. You could memorize them with the table below, or, if you are familiar with the keyboard, you could note that, if you start on C and go upwards, every interval you form with a white key will be either major or perfect. (Note: knowledge of a piano keyboard is helpful in many music theory situations. I would recommend that you start working with the keyboard quiz as soon as you are finished with note names.)
Interval | Number of Half Steps |
Major 2nd | 2 |
Major 3rd | 4 |
Perfect 4th | 5 |
Perfect 5th | 7 |
Major 6th | 9 |
Major 7th | 11 |
Perfect 8ve | 12 |
Examples Let's try a few. For example, take E to Bb: from E to B is a fifth (E, F, G, A, B), but this fifth (E to Bb) is only 6 half steps, not 7. Looking at the table of qualities above, we see that E to Bb is a Diminished 5th. Let's try another: Db to Gb. D to G is a fourth (D, E, F, G). You may be thinking at this point that the G is lowered, but be careful—it is not the accidental of the note that determines the quality, it is the number of half steps. Db to Gb is 5 half steps, so it is, in fact, a Perfect 4th.
Enharmonic Intervals Note that there can be multiple names for the same number of half steps — for example, an augmented fourth and a diminished fifth are both 6 half steps. These "enharmonic" intervals function quite differently in actual music, but since this quiz presents intervals completely out of context, it treats them as being equal (in fact, they differ slightly in tuning, but it is negligible for our purposes).
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