maybe a stupid question- theory- diminished intervals

[Glissando]

Okay, so I'm trying to learn all this theory stuff that I haven't been taught before, and came to diminished intervals. No problem- you take a major interval and lower it by half a step, and its called a diminished chord. To lower a flat, you would write bb.
Okay, fine- but...
Then they show all these diminished major intervals, and some of them have a b and some have a bb.
Okay, why do some have a bb and others don't?
Would it be because the key its written in is a major key with flats, and that's why it some of the notes have bb?
I have a horrible feeling that the reason, whatever else it is, is obvious, and I'm disgracing myself forever by asking.

[dmk]

Hey Gliss,

I think your a little confused so here is my best explanation:

Take a major 3rd for example (for ease C-E).  If you lower this a semitone (half step) you get a minor 3rd C-Eb (if you want to check this out play your minor scale).  If you lower it another semitone you get a diminished third (C-Ebb).  So a diminished interval is a tone (whole step) lower than a major interval.  (IE AMINOR INTERVAL IS A SEMITONE LOWER THAN A MAJOR INTERVAL)

If you have a perfect interval (lets say a perfect fourth C-F) and you lower it a semitone (half step) C-Fb it is a diminished 4th.

As to flats and double flats this will depend on your key signature.  The easiest and most fool proof way to work out intervals is to always work them from the major scale and remember that:
 - a minor interval is a semitone lower than a major
 - a diminished interval is a semitone lower than a perfect and a semitone lower than a minor (or a tone lower than a major).  The opposite is true for augmented intervals

Good luck!!!!

dmk

I hope this helps you, a question asked is never a stupid question.

[Glissando]

Thank you so much dmk!
It makes sense now. I was awfully confused- maybe teaching yourself theory isn't such a great idea after all.

[rhapsody in orange]

Hello gliss.
Well teaching yourself theory can be quite fruitful too! That's what I'm doing now since my teacher's been busy and I'm preparing for an examination. It would be very helpful if you have friends who are already proficient in this field (I'm very thankful for them). Otherwise, I'm pretty sure people in this forum would be glad to help if you have any problems. Have fun learning theory! A pretty interesting thing to know about =)

[bernhard]

To add to what dmk said, in the matter of intervals you must always think ASK (Alphabet – Score – Keyboard).

Take the major third C-E. Why is it a third?

1.   Because it involves three letters (Alphabet): C-D-E.

2.   Because on the Score they are written on two consecutive lines (thirds will always be on either tow consecutive lines or two consecutive spaces).

3.   And because it involves three keys (Keyboard) on the scale of C major: C-D-E (Db and Eb the two black keys are not part of the C major scale).

Why is it major? Because a major third interval covers 4 semitones, which is the case here.

Now take the minor 3rd C-Eb. Why is it a third?

1.   Because it involves three letters (Alphabet): C-D-E(b).

2.   Because on the Score they are on two consecutive lines (thirds will always be on either two consecutive lines or two consecutive spaces).

3.   And because it involves three keys (Keyboard) on the scale of C minor: C-D-Eb (Db is not part of the C minor scale).

Why is it minor? Because a minor third cover 3 semitones, which is the case here.

Finally take the diminished third C-Ebb. Why is it a third?


1.   Because it involves three letters (Alphabet): C-D-E(bb).

2.   Because on the Score they are on two consecutive lines (thirds will always be on either two consecutive lines or two consecutive spaces).

3.   And because it involves three keys (Keyboard) on the scale of Db minor: C-Db-Ebb.

Why is it diminished? Because a diminished third cover 2 semitones, which is the case here.

Now on the Keyboard, Ebb and D are the same note (= enharmonic). So if I play C-D it is a second (two letters on the Alphabet; placed on contiguous line and space on the Score), but if I play C-Ebb this is a diminished 3rd. The point here is simple: C-D and C-Ebb are the same only in regards to the keys (Keyboard). They are completely different as far as the Score is concerned, and as far as the Alphabet is concerned. (This hsould answer the question: "Why bother with Ebb if it is the same as D?" Well, as I said it is the same only as far as the keyboard is concerned. It isnot the same as far as the Score and the Alphabet are concerned).

In an equally tempered instrument like the piano, they will also sound the same, but in any other tuning C-D will actually sound different from C-Ebb. Finally, the scales generating C-D and C-Ebb will necessarily be different.

Finally so that you do not get totally confused, there is a relationship between intervals and scales, but it is not as clear cut as it may seem. For instance, the major 3rd C-E occurs in the C major scale, but also in the F major scale. In fact, any scale that has the notes C-E will have this particular major 3rd (C major, A minor F major, D minor, G major, E minor).

Likewise, the C minor interval can appear in any scale that has the notes C and Eb. Can you tell which scales have it?

All clear as mud?

Best wishes,
Bernhard.

[Glissando]

Wow.
Thanks for all the info, Bernhard! Very interesting and helpful. You are so informative!!!

Orange- no don't know anyone who knows any music theory, except my teacher, and for some reason which I don't know we haven't been working on it together (although she knows I want to). So you guys are going to have to help me with it.
Good luck on the exam!

[djbrak]

Here are some helpful websites:
https://www.musictheory.net/
https://www.teoria.com/
https://www.emusictheory.com/
-Ren