Originally Posted by: WilldridgeI'm a bit rusty in my theory, so I'll gladly retract this if someone can tell me otherwise, but...

If I recall correctly, an Altered chord is simply a generic name for chords that go beyond "Extended" chords - they have their own specific name which is often forgotten because of the theory involved behind them. Alt isn't necessarily the name of the chord, just an indication that it is non-standard (root, 3rd, 5th), or extended (root, 3rd, 5th, 9th, for example)

I believe Dominant and Diminished chords are classed as Altered chords, where as Dsus4 is classed as an extended chord. That would explain why you can have the same chord "name", even though the theoretical structure is different.

There's more theory behind all this which I can go into if you'd like, but I'm hoping that should be succifient to answer your question

I'm 99% sure that's right - would anyone care to prove or disprove the remaining percent?

Hope that's of some use...

Hey.
I really apreciate you taking the time to answer this question.
But unfortunatily your theory fails in the fallowing:

1._You said that an Alt chord is a chord that goes beyond extended chords.
Well, many chords go beyond extended, and are not consider Alt, for
example:
13#11=[1,3,5,7b,9,11#,13]
-13#11=[1,3b,5,7b,9,11#,13]. etc
2._You also said that Dominat and Diminished chords are classed as Alt.
Not true. We have a group of chords that belong to the Dominant type.
But each chord has an specific name, for example:
7
-7
7sus2
7sus
7b5, etc
And for the Diminished group:
o
o7
1/2 dim, etc
Do you see how each chord has its own name?

3._ You said that a Sus4 is classed as an extended chord, and that is not
true eather.
A chord of the sus4 type; uses three notes of the scale:
Sus4=[1,4,5]
it belongs to the "Suspended Chords" group and each chord has an
specific name:
Sus
Sus2, etc.
Again. Do you see how each chord has a name?


So here we go back to the original question. Why those four chords, which are different in structure and quality have the same name?