Augmented 5th and minor sixth (8 semitone interval)

Folks, got this from the net when studying some chord theory:

The only other triad which appears to have full mutual consonance is the augmented triad (1 - 3 - sharp5). On a piano keyboard this triad appears to contain two major thirds and a minor sixth - all of which are consonant, but in actuality the interval between the top and bottom tones is not the consonant minor sixth but the dissonant augmented fifth.

The augmented fifth and the minor sixth may be represented by the same number of semitones in 12-tone equal temperament, but this does not mean that the aural effect of these two intervals is the same.

This may seem paradoxical and somewhat pedantic, but it is not - neither in a theoretical nor an empirical sense. The augmented fifth is a disturbing interval, even when expressed in equal temperament.

Can the experts explain how can the same 8 semitone interval be consonant and dissonant at the same time :shock:

 

Minor sixth is not really consonant interval(atleast aurally, it sounds terrible).
They classified minor sixth to be consonant only in some concept called 'just intonation' (where frequencies of notes are related to a whole number, and just google it u will get the theory).

And you asked how the same 8 semitone interval can be consonant and dissonant at same time.
Answer is inversion.

go with an example C augmented - C + E + G#
C to G# is a minor sixth interval, dissonant.
Invert them, check the interval between G# to C, it'sa major third and consonant.

 

whts a consonant & dissonant???

 

Eh! I find the whole augmented scale dissonant.

 

OK, so with equal temparament both are dissonant. Good.

@Johny, consonant intervals sound pleasing while dissonant intervals suck.

 

^^ Really? I mean, no jokes right?

 

^ HEHE
Man its all according to classical theory.

When they thought that flat5th note and interval is evil sounding and invokes spirits from the hades.

Infact if you observe, Toni Iommi has used the b5th pretty often in his leads/licks/riffs just to make his music more evil and menacing.

Sounds stupid but true. Check out the intro riff (the extreme slow one) of Black Sabbath (the song)


Just for info, the use of b5th was banned by church in the medieval ages. :RollLol:


Ofcourse now everyone seems gung-ho about using it.

 

And check out the intro to Purple Haze by Hendrix. The Guitar and Bass harmonizes at b5 interval. The Guitar plays Bb Root and Octave and the Bass plays E Root and Octave...Genius :nw: :nw: :nw:

 

^ Yeah but that sounds dissonant hbbt:

 

yes but when u invert u r no longer talking abt the same interval

 

no with equal temperament both r 'softly consonant'

 

What is softly consonant?

 

yes you are right

 

this frm an earlier post
https://indianguitartabs.com/showthread.php?t=19899

Code:

1-1 open consonance 	unison
1-2 sharp dissonance 	minor second 
1-3 mild dissonance 	major second
1-4 soft consonance 	minor third
1-5 soft consonance 	major third
1-6 consonance/dissonance perfect fourth
1-7 neutral/restless 	augmented fourth/ diminished fifth
1-8 open consonance 	perfect fifth
1-9 soft consonance 	augmented fifth/ minor sixth
1-10 soft consonance 	major sixth/diminished seventh
1-11 mild dissonance 	minor seventh
1-12 sharp dissonance 	major seventh
1-13 open consonance 	octave  

 

Good to know that. What was your source of this information @zing because I never came across this earlier.

 

^ LOL, I didnt know: sometimes even you can be sarcastic.

 

theres a gr8 book called 'playing guitar' if u get it buy it

 

finally u realized ther r sum things u dont know

 

Intervallic harmony is always contextual. The use of a augmented fifth or a minor 6th is different because they will be use differently in a scale. For instance, if you are using the augmented fifth, then you will have a sharpened fifth note and then a natural 6th a semitone up. If you use the same note as a minor 6th, you will have a natural 5th and then a minor 6th a semitone up.
@alpha1: Augmented interval is different from augmented scale. The former can be used even without needing to use the scale, in the same way you use a B diminished chord in the C major scale.

 

Correct, but the tonal mood is same.
Minor scale differs from Major scale in a similar way as minor 3rd interval differs from major 3rd.
Ofcourse, it houses other intervallic differences too, giving the scales more flavour than just minor3rd or major3rd.