The power of Repetitiveness

Talk about what you've discovered by using ETC-- and post your high ranks!
paulriley
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Postby paulriley » Tue Mar 25, 2008 3:45 pm

when you say average frequency, is that the actual frequency that is being produced out of the speaker? what happens when two live instruments are playing?

aruffo
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Postby aruffo » Tue Mar 25, 2008 4:08 pm

I was curious so I took C4 and C5 and combined em, then compared the resultant wave to a G4 (making sure they all had the same phase). Here's the result.

Image

djf
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Postby djf » Tue Mar 25, 2008 4:35 pm

That's exactly what I would expect. The 2:3 ratio is the same ratio as C4:G4, and the C5 waveform sort of gets "embedded" in the C4 waveform because that's a simple 2:1 ratio. The thing is, there's nothing about that waveform that suggests that the two tones shown are in any way "the same". The combination tone has an overall period that's the same as that of C4 because it's essentially a difference tone: C5 - C4 = C4 (using crazy music math).

gavriel
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Postby gavriel » Tue Mar 25, 2008 4:49 pm

Niccceee.
There you have it.
The distances between the vertical red lines (between the "zeros") is the frequency. It is objectively the same.
The distances between the tops of each wave is the chroma. These are different.
On the upper sound you have the upper tops, the distance of which is the frequency of C4 and then the "mini tops" which add another mini top in between every two upper tops and thereby double the frequency (this is the C5).
The distances between the tops are greater on the upper sound than on the lower one. They are standing in a ratio of 2:3 (C4:G4) and 3:4 (G4:C5). Which makes perfect sense since:

C4 = 261.63Hz
and 261.63*3/2 ≈ 392 (which is a G4)

G4 = 392Hz
and 392*4/3 ≈ 523.25Hz (which is a C5)

So there you have it an objective representation of a sound with the chroma (top to top distances) of C notes (≈262Hz and 523Hz), but at the same time a distance of 392Hz from one zero level to the other (height of a primary G note).

These zero levels start a new major wave in the upper sound in sync with a major wave start in the lower sound once per three waves. That explains what I was writing before about "timbre and fractional height takes time" to be perceived. ...
More time than simple height and chroma.

First we perceive simple height/chroma (in that case we hear a compound C or a G)
Then we perceive fractional height (in that case we start hearing a sameness between the C and G)
and lastly we perceive timbral character.

In that sense one could describe AP as more "Patient" listening and RP as an "impatient" listening. Fractional height cannot be perceived right away, you need to allow many tops go by before you can recognize the fractional ratio between these tops and see if it repeats over at least three cycles before you can recognize fractionaly.


Edit: sorry corrected some mistakes above...
Last edited by gavriel on Tue Mar 25, 2008 5:51 pm, edited 1 time in total.

djf
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Postby djf » Tue Mar 25, 2008 5:22 pm


aruffo
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Postby aruffo » Tue Mar 25, 2008 9:39 pm


djf
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Postby djf » Tue Mar 25, 2008 10:22 pm


TS
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Postby TS » Wed Mar 26, 2008 8:45 am


paulriley
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Postby paulriley » Wed Mar 26, 2008 2:22 pm


djf
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Postby djf » Wed Mar 26, 2008 3:04 pm


paulriley
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Postby paulriley » Thu Mar 27, 2008 8:16 am


gavriel
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Postby gavriel » Sat Mar 29, 2008 6:56 pm

Hi all,

Here is an image explaining part of what I meant:

Image

Every two cycles of C4 (green)
Every four cycles if C5 (red)
and every three cycles of G4 (yellow)
Equal one compound cycle of C4+C5 (or of G4 with a C chroma)

At the beginning of every compound cycle the air pressure will be the biggest, since that is when all cycles have a "top" at the same time.
This compound top is what gives the sensation of fractional height.
At all other instances only one of the cycles experiences a top.

Study this chart carefully and you will see that the upper sound can only be a result of a compound C chromas with the height of a G. Objectively.
I am using the middle levels instead of the tops or bottoms because it is easier to draw the lines that way.

I have much more to say about this! but cannot type much right now since I am on tour... and have to work (on stage).
Will post more later.

TS
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Postby TS » Sun Mar 30, 2008 2:40 am


paulriley
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Postby paulriley » Sun Mar 30, 2008 7:01 am


djf
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Postby djf » Sun Mar 30, 2008 10:58 am



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