Theory question: intervals

[lord667]

I've been studying (perhaps that's too strong a word) some theory, and I'm given to understand the following:

All unison, octave, perfect fifth, major/minor third and major/minor sixth intervals are "consonant".

All major/minor second, major/minor seventh, and any augmented or diminished intervals are "dissonant".

Perfect fourths are consonant in melody but dissonant in harmony.

However, I'm confused on one point. Augmented fifth = minor sixth, for all intents and purposes, right? But that means that a four-tone interval is both consonant AND dissonant. I'm assuming it depends on the context, but how you differentiate? Under what circumstances will a minor sixth be, in fact, dissonant?

 

[Pita Bread]

Depends on what the root of the chord is, and what key you are in. If memory serves me right, to augment, you raise a note by a half step, which could technically make it a 6th.

In C Major: let's say your root is C. A 6th would be C + A; an augmented 5th would be C + G#. In this case, the G# is not in the key of C Major, and if you play the augmented 5th chord, it is "off key" and dissonant. On the other hand, the major 6th sounds consonant.

However, in a minor: make your root A. A 6th would be A + F; but an augmented 5th would also be A + F, because a half step above E (the 5th) is also F.

I'm not sure if this helps or not, but hopefully it does; if need be, I'll dig through my theory books, 'cause I'm a bit rusty on theory as of right now.

 

[lord667]

I'm not sure about that. If 2nds, 9ths and 7ths are dissonant, then you can have dissonant chords that are still in key, right?

 

[Pita Bread]

Good point. Can you give me a definition of "consonant" and "dissonant"? I'm starting get confused about this matter too.

 

[lord667]

Good point. Can you give me a definition of "consonant" and "dissonant"? I'm starting get confused about this matter too.

Basically, I think dissonant intervals are those that (within a traditional Western context) sound jarring and seem to require resolution, consonant intervals are harmonious and do not. That's what confused me, because the aug5/m6 (and the dim4/maj3 too, I realised) can apparently fall under either category.

 

[bobvex]

Consonent = nice

dissonent = gross

and 6ths and 2nds and 7ths dont neccesarily sound dissonant, but they are a less used interval

and the augmented 5th = minor 6th thing - wrong. . it all depends on the key like. . .pita said but i shall clarify

In C Major: let's say your root is C. A 6th would be C + A; an augmented 5th would be C + G#. In this case, the G# is not in the key of C Major, and if you play the augmented 5th chord, it is "off key" and dissonant. On the other hand, the major 6th sounds consonant

major scale - c, d,e, f, g, a, b, c

in key of C - augmented 5th = g#, or an Ab depending on circle of fifths

LEARN THIS PICTURE the shapr notes are the flat in the key, if a note falls on that line, without a natural sign it will be either sharped or flatted, so lets say you are in the key of G, the sharp is a F# (i think. . this is from memory) so there cannot be such a things as a Gb becasue G is already taken up by the root note. . the thing with scales and shit, one note letter cannot be repeated

learn this shit. . it helps. . .a fucking lot. .
Correct
Major G Scale - G A B C D E F# G

Incorrect
G A B C E Gb G

 

[lord667]

Consonent = nice, etc.

Many thanks. This is the kind of thing I was looking for.

 

[Indiooo]

What is consonant to you may be dissonant to others. There is no definition, as far as I know. Jazz guys find tritones and major sevenths nice, so go figure... Some classical musicians find perfect fourths dissonant in certain contexts... It's all relative.

 

[Wound]

ignore the consant and not shit. You have 4 perfect intervals, unison, 4th, 5th, and octave (8th)

tritone is not a minor sixth, tritone is a tritone and only that.

it goes like this..

unison m2 M2 m3 M3 P4 P5 Tritone m6 M6 m7 M7 8

M7 is a leading tone, it makes your ear want to hear a cadence.

 

[lord667]

tritone is not a minor sixth, tritone is a tritone and only that.

Yes, I wasn't talking about the tritone (that's a dim5 or aug4), I was thinking that the aug5 and m6 are the same because they are both four tones. I needed to know the contexts under which a four-tone interval would be one or the other.

unison m2 M2 m3 M3 P4 P5 Tritone m6 M6 m7 M7 8

Actually, the tritone comes between P4 and P5 - I'm assuming you're listing them in order of semitones.

M7 is a leading tone, it makes your ear want to hear a cadence.

That's what I'm picking up on as part of the definition of "dissonant". I don't know if that's a universal usage or just a few people's opinion though, I need to read a little wider to find out.

 

[Wound]

yeah, tritone is between p4 and p5, i blew it

Dissonance is really an opinion. The most common dissonate intervals are m2 and the tritone.

try playing a root, m2, tritone chord on guitar.... evil!!

and don't ask what you would call a chord like that, because i have no idea. You have to kind of make it inverted though so it is tritone lowest, then root, then the m2.

 

[Wound]

Oh, aug5 and m6 *could* be considered the same note. But if the scale is a major scale, the 6 is a M6 so you would make the 5th augmented.. that's sort of my take on it. Theory is messy.. like sex!

 

[lord667]

try playing a root, m2, tritone chord on guitar.... evil!!

That does sound pretty cool.

and don't ask what you would call a chord like that, because i have no idea. You have to kind of make it inverted though so it is tritone lowest, then root, then the m2.

Hmm, a challenge! Well...if you put the m2 at the bottom of the stack, then the tritone, and then the root on top, you've got a P4 and a maj7...so...it's an inverted maj7add4, played without the fifth and third?

That sounds ridiculous. Someone give us the answer, please!

 

[Wound]