3rd, 5ths, perfect 4ths?!?


New member
Well, thirds are what western music is built on.
This is where our ears have been trained over all.
Then the basis of western music is then based
on the I, IV, V progression, or a slight variation.

The Numerical meaning of thirds, fourth's, fifths
is the scale degrees of the key your in.
So this is the numbers of any scale we are in.
1, 2, 3, 4, 5, 6, 7, 8.
8 is the same as 1, known as the octave.

Stacking thirds, is called triadic harmony.
This is the building blocks of western music.
And also where are ears gravitate to when
we are building a slue of notes, or writing.

The I, IV, V chords are built on stacked thirds.
And cover the complete scale or key we are in.
This is the I, IV, V built on the numbers of the scale.

I = 1, 3, 5
4 = 4, 6, 8(1)
5 = 5, 7, 9(2)

Or like this too.

Going bottom to top
from 1, 4, 5 on the very bottom row up.
5 - - - - 8 -2
3 - - - - 6 -7
1, 2, 3, 4, 5, 6, 7, 8
(this is not formatting correctly
The BB Code is removing the
second space I am trying to use.
This is more the parser for PHP
and the BB Code. The parser
is what writes out the code after
we type something out.
The Parser is hard coded to see
only one space.)

As you can easily see these
are in fact stacked thirds.

and when we see the notes on the music
staff this is how the notes are written, stacked.

As a lot of music today like,
rock and metal use only the
1 and 5th scale degrees
when playing the I, IV, V progression.

This leaves all kinds of space for wild
sounds, keyboards, singing, cranked up amps
fill this sound very fast as dose effects and layering
tracks etc, or even leaving this musical space for the
bass player, and even the singer if the music is written good.

Jazz uses a bit more "stacking" of thirds, forths, fifths
and the numbering for them can be seen as basic addition
on top of what we have seen above on "Going bottom to top" I wrote out.

The numbering system for jazz type of chordal stacking is then
based on the same 1 - 8 system? but after 7 we have then
the numbering system like this, the bottom row is the complete scale, and key.
and the top row is the scale degrees after 7. still the same scale degrees, but
now they are written one octave above the normal 1 to 8 scale degrees.
Mathematically an octave is twice the amount above the underlying scale degree
But here we are looking at the stacked notes of the key above the scale we are in.

8, - 9,- 10, - 11, - 12, - 13 - 14, - 15
1, - 2, - 3, -- 4, --- 5, --- 6, - 7, -- 8
(this is not formatting correctly)

So at this point? we have every scale degree covered
and then we also have the octave above this scale as well.
Stacking notes is all harmonic related, chords, etc.

I will add some more to this as I get it formatted right.
It's hard to format this here as the alignment gets messed
up from using the non standardized BB Code.

But this a great start and I might even add even more
as to see how everything related to a well known written song
on the musical staff as to aid in ear training and sight reading.

The resolution of these scale notes as they move about
in a song is where I am heading, but this should prove
rather hard on me as the BB code is hard to work with.

Updated Aug 30th, 8:45 PM
I will being adding more as I write everything out above
in Ardour DAW so we can see it and hear it. I will make
a video of the above content and then see how that goes.

We have no formal means of writing music in the digital
world, not like we do for say screen writing? Or TV over all.

So using a tool like Ardour may help some.
I am currently using Ubuntu Studio 20 LTS.


New member
Bronco":252iiwvr said:
crankyrayhanky":252iiwvr said:
Yes, that is it!
Aren't 2nds refered to as "9ths" though? :confused:
It depends on which octave they are placed. They sound different and that's what the 9th is trying to capture. Don't confuse music theory with music, music theory is trying to understand and explain why things sound good according to western music, but music can be made without adhering to those rules. It's an explanatory tool, not necessarily a prescriptive set of rules.


New member
Just adding to this, the "perfect" label is referring to how consonant an interval is, and so perfect intervals are considered to be the most consonant intervals. In fact, octaves and unisons are considered perfect intervals too. Something else interesting is that there's a very old debate as to whether or not the 4th is really a perfect interval.
I'm just going to mention this is the only post on this thread that is correct.

The label "perfect" has to do with the harmonic series and temperament. If you play a note at 440 hz, the harmonics are 880 hz (440*2), 1320 hz (440*3), ... If you expand the first few harmonics, they are root, 5th, root, major 3rd, 5th, root, ...

So why is the major 3rd not a perfect interval? The reason is how it relates to temperament. In western music, we use the exponential intervals. In other words, 2^(i/12). For a perfect 5th, if you plug in 440 hz *2*2^(7/12) you get 1318.5 hz, which is very close to the harmonic at 1320 hz. This makes it consonant. If you do the same thing for a major 3rd you get 2217.5 hz, which is further from the harmonic at 2200 hz. It isn't as far as a dissonant interval, but it isn't close enough to be perfect.

The other part here, theory does not agree on whether or not a 4th is perfect. It is consonant, but it is not a harmonic. The only reason it is consonant is because it is the inverse of the perfect 5th.

You can follow the circle of fifths and harmonics of harmonics to explain why other intervals that are not an octave or 5th are not perfect.
Last edited: