Naming intervals by number and quality

INTERVALS BY NUMBER

The trick to giving intervals their numeric value is to count the first note as ONE (it is also called a “unison”), NOT ZERO.

QUALITY: PERFECT, MAJOR and MINOR

Always think about intervals from the major scale beginning on the lower note.  If the top note fits into the major scale beginning on the bottom note, it will be a PERFECT or MAJOR interval.  The PERFECT intervals are Unison, 4th, 5th and Octave, all others are MAJOR (that is, 2nds, 3rds, 6ths & 7ths).

A MINOR interval is one semitone shorter than a major interval.

QUALITY: AUGMENTED and DIMINISHED

Beyond these three (Perfect, Major and Minor) there are two other qualities of interval.  AUGMENTED can be applied to any interval: it is one semitone larger than a Major or Perfect interval.  DIMINISHED can also apply to any interval, and is one semitone smaller than a Perfect or Minor interval.

TWO HELPFUL HINTS

Firstly, remember that it is possible to find EVERY type of interval within a major scale ... if the lowest note on the interval is not the first note of the scale.  Name these intervals, all found in C major:

Secondly, naming intervals where the lower note is an accidental can be a problem, because of having to think about complicated key signatures.  But there’s an easy way around this.

Look at the first pair of intervals in the next example [refer to the worksheet].  The first two intervals are the same - they are both a major third, but in the case of the second interval I’ve removed the sharps so it’s easier to work out.  You can do this to any interval, so long as you do the same to BOTH notes at the same time - remember that adding a flat has the same effect as removing a sharp and vice versa.  Have a look at the following three pairs.  Notice the change in the notes from the first example to the other, and name the intervals according to quality and number.

Also, notice that you should NEVER change the note names, only the accidental.

Here's our worksheet for this topic:

https://docs.google.com/open?id=0B9JdpU-tw7FuOWE3Q01kZ3ZJYWc