The minor is decreasing Major intervals (2nd, 3rd, 6th, 7th) by half step.
Diminishing means made the perfect or the major intervals smaller by half step as well.
So what is the difference? I am confused.
Here are captures of the two lessons.
Diminishing means made the perfect or the major intervals smaller by half step as well
In contrast to Laurence Payne, I'm going to say that the preceding statement is not correct. The correct statement would be
Diminishing means made the perfect or the minor intervals smaller by half step as well
So, for example, a major sixth comprises 9 half steps. A minor sixth comprises 8, and a diminished sixth comprises 7.
The way I like to think of it is this:
Intervals are either perfect or imperfect. The former (ignoring intervals larger than an octave) are the unison, the fourth, the fifth, and the octave. The latter are the second, the third, the sixth, and the seventh.
Perfect intervals have one "normal" size, where "normal" means neither diminished nor augmented. The unison is zero half steps, the fourth is five half steps, the fifth seven, and the octave twelve.
Imperfect intervals have two "normal" sizes, major and minor. The minor size is always one half step smaller than the major size. The minor second is one half step; the major second is two. The minor third is three half steps; the major third is four. The minor sixth is eight half steps th r major sixth is nine. The minor seventh is ten half steps; the major seventh is eleven.
The next smaller size than perfect (for a perfect interval) or minor (for an imperfect interval) is diminished. The next smaller size after that is doubly diminished, and so on.
The next larger size than perfect (for a perfect interval) or major (for an imperfect interval) is augmented. The next larger size after that is doubly augmented, and so on.
You could look at the matter in a simple way:
The intervals 2nd, 3rd, 6th and 7th can be either small or big. Small ones are called minor, big ones major.
The small ones can be dimished, the big ones can be augmented.
The perfect intervals can be either diminished or augmented. (Exception: the perfect unison can not be diminished.)
EDIT: I wrote the above answer yesterday, and today I decided that some elaboration could be useful as follows:
@user21245 I think your confusion comes from the way the author describes the minor intervals in the way he relates them to major intervals. It is correct that there is a half tone difference between them, like a minor 3rd is a whole step followed by a half step, while a major 3rd is a whole step followed by another whole step. But a minor interval is its own independent interval not derived from a major interval. Just regard the author's description of the major and minor intervals as a way to describe the difference between them. Point: nothing is diminished in a minor interval.
You can find all the minor intervals on the white keys on a piano without diminishing or decreasing anything.
I think a good way to get a handle on the terminology of intervals is to understand first the relation of internals to a tonic in the major/minor system. After that you can then apply the terminology to any interval. It's sort of a diatonic to chromatic approach.
Let's assume a tonic of
C and a major scale.
The various degrees (tones) of the scale have significant relationships to the tonic.
The tonic and the fourth and fifth tones are the tonal degrees, they set the tonal center. In major and minor scales the fourth and fifth are a perfect fourth and perfect fifth above the tonic. Add to those the unison and octave to the tonic, both of which are also perfect intervals, a perfect unison and perfect octave.
The second, third, sixth, and seventh degrees are the modal degrees, they set the mode - whether the scale is major or minor. These various degrees and their intervals above the tonic are either major or minor. For example, in a major scale the intervals are major second, major third, major sixth, and major seventh. The intervals for a minor scale are more complicated, but we can skip that for now.
That's my way of explaining why some intervals are named perfect and other major/minor.
Diminished and augmented are modifiers added to the interval names when you shrink or enlarge them by a half step.
You can add double, triple, etc to diminished/augmented to make unusual intervals like a double diminished third. But that brings up enharmonic interval naming and you can skip that for now.
...Diminishing means make the perfect or the major intervals smaller by half step as well.
Correction: make smaller a perfect or minor interval.
...The minor is decreasing Major intervals
It may be helpful to think of perfect, major, and minor as qualifiers added to generic intervals. A third is generic. A minor third is qualified. Those qualities are set by the key signature. Perfect, major, and minor are adjective.
Diminish and augment are verbs. They modify. (The exception is the tritone,
C major, but let's skip that complication for now.)
The adjective/verb distinction is not perfect, but it might help you get a handle on the concepts. Minor and diminish don't really have the same meaning of making something smaller.
You don't minor a third. The minor quality is basically set by the key signature or accidentals that change mode/key.
You can diminish a minor third. For example in
C minor you can change the minor third
F Ab to a diminished third
F# Ab (leading to a unison on
So, let's say the situation is
C major and you change the major third
C E to a minor third
C Eb, what is the modification to speak of? We aren't minoring the third, and we aren't diminishing the third. Probably it's best to speak of lowering the third to change it to minor. That describes the operation and the result is a shift to the minor mode.
"Diminishing means made the perfect or the major intervals smaller by half step..."
Well, sort of. Using 'diminish' with its everyday meaning of 'make smaller' you're quite correct. But there's a special musical meaning of 'diminished' when naming intervals. Start with a major interval. 'Diminish' it by a half step, it becomes a minor interval. 'Diminish' by another half-step, we call it 'diminished'.
Now, Perfect intervals are different. Contract it (enough with the confusing word 'diminish'!) by a half step, it becomes 'diminished'. It doesn't go to 'minor' first.
(Make either a major or perfect interval BIGGER by a half step, it's called 'Augmented'. No special treatment for perfect intervals here.)
OK that's what happens. 'Why?' you ask. And that's a harder question. I can tell you another characteristic of Perfect intervals - when you invert one - put the bottom note on top - it remains Perfect. Whereas inverting a major interval results in a minor one and vice versa. But that's just another characteristic of Perfect intervals, it doesn't really deal with the 'why' of them. Enjoy your research, if you're interested, though I suspect the topic's a bit above your current level of study. Maybe just stick to learning how intervals behave for now. Leave the 'why' for later.
All the answers shared above are good. I’ll just like to add a bit of help to make it easier for you to remember.
Think of all intervals within a major scale from the root. (Think C D E F G A B C) Categorize them into 2 groups:
Group A: PERFECT (Members: 1st, 4th, 5th, 8ve)
diminished <— Perfect —> Augmented
Group B: IMPERFECT (Members: 2nd, 3rd, 6th, 7th)
diminished <— minor <— Major —> Augmented
(Actually I like to think of the second group as Major, but the correct term would be imperfect).
Hope it helps you visualize and remember better. :)
Augmented means one half step more than major or perfect, while diminished means one half step less than minor or perfect. So, a "tritone" such as C-F# is an augmented fourth, while the same thing written C-Gb is a diminished fifth.
In practical terms, you'll see a diminished fifth in a dominant seventh chord, for example C-E-G-Bb has a diminished fifth between E and Bb. Also, you will see an augmented second in a harmonic minor scale, for example A harmonic minor is A-B-C-D-E-F-G#-A. The augmented second is between F and G#.
Of course, an augmented second is the same notes as a minor third, and can be written as such: A-B-C-D-E-F-Ab-An is the same notes as the A harmonic minor scale; F to Ab is a minor third. It isn't written this way because it's clearer to have each note of the scale on a separate letter ("scale degree") rather than two notes on the same scale degree differentiated with accidentals. So, the augmented and diminished intervals are usually used because they are a clearer alternative to some other way of writing the same notes.