OD: Difference between revisions

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An '''OD''', or '''otonal division''', is a kind of [[Arithmetic tunings|arithmetic]] and [[Monotonic tunings|monotonic]] tuning.
An '''OD''', or '''otonal division''', is a kind of [[Arithmetic tunings|arithmetic]] and [[Monotonic tunings|monotonic]] tuning.


Its full specification is n-ODp: n otonal divisions of interval p.  
Its full specification is n-ODp: n otonal divisions of rational interval p
 
The only difference between n-ODp and n-EFDp is that the p for an [[EFD]] is irrational.  


The nth [[Overtone scale|overtone mode, or over-n scale]] is equivalent to n-ODO. So is n-[[ADO]].
The nth [[Overtone scale|overtone mode, or over-n scale]] is equivalent to n-ODO. So is n-[[ADO]].


An OD is a specific (rational) type of [[EFD|EFD, or equal frequency division]].
If you want to describe overtones 1-9 with OD you would need to use 8-OD9, because there are only 8 steps from 1 to 9. You could think of it like 9 is the 8th overtone, so you're really dividing 8 by 8. You're dividing the number of overtones. Alternatively, you could describe his as an [[OS|OS, or overtone sequence]], by simply saying 8-OS.
 
note there's a kinda tricky aspect which is that if you just want overtones 1-9 you need 8-OD9 because there are only 8 steps from 1 to 9. You could think of it like 9 is the 8th overtone, so you're really dividing 8 by 8. You're dividing the number of overtones.


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Revision as of 22:12, 22 March 2021

An OD, or otonal division, is a kind of arithmetic and monotonic tuning.

Its full specification is n-ODp: n otonal divisions of rational interval p.

The only difference between n-ODp and n-EFDp is that the p for an EFD is irrational.

The nth overtone mode, or over-n scale is equivalent to n-ODO. So is n-ADO.

If you want to describe overtones 1-9 with OD you would need to use 8-OD9, because there are only 8 steps from 1 to 9. You could think of it like 9 is the 8th overtone, so you're really dividing 8 by 8. You're dividing the number of overtones. Alternatively, you could describe his as an OS, or overtone sequence, by simply saying 8-OS.

example: 4-ODO
quantity (0) 1 2 3 4
frequency (f) (4/4) 5/4 6/4 7/4 8/4
pitch (log₂f) (0) 0.32 0.58 0.81 1
length (1/f) (4/4) 4/5 4/6 4/7 4/8