Why some notes are better than others

uncloned · January 14, 2010, 01:15:25

I have to post a link because the picture in huge for a forum.

http://upload.wikimedia.org/wikipedia/commons/f/f9/Dissonance-a220-a440-notated.jpg

which comes from this article

http://en.wikipedia.org/wiki/Consonance_and_dissonance

Experiment

Take two sine-like sounds - start them both at 220 hertz (A3) equal volume and move one up by an octave to 440 Hz (A4) in 30 seconds.

Important point - the places in the graph where "resonance" occurs seem to be (more or less) where we have the notes of the piano. These places are also related to the harmonic series which explains why there are more than one type of minor third or other intervals.

Guide

interval, name, example notes
M2 major 2nd A - B
m3 minor third A - C
M3 major third A - C#
P4 perfect 4th A - D
A 4 augmented 4th (tritone) A - D#
P5 perfect fifth A - E
m6 minor 6th A - F
M 6 major 6th A - F#
m 7 minor 7th A - G
M7 major 7th A - G#

Sam_Zen · January 15, 2010, 00:55:50

Thanks, Clones, very interesting !
Not that much looking to compare it with a well-tempered scale, but noticing these relations like 9:8 or 17:9.

uncloned · January 15, 2010, 01:32:53

music that uses those pure ratios as its tuning is called "Just Intonation"
It goes back to before Pythagoras.

http://en.wikipedia.org/wiki/Just_intonation

Sam_Zen · January 16, 2010, 00:44:37

It gets more interesting.
I'm going to investigate the behaviour of my analog synth when using oscillator synchronisation.
Maybe the same ratios are occuring there.

uncloned · January 16, 2010, 00:56:41

it is very likely it does - in fact no reason I can think for it not to occur.

Sam_Zen · January 16, 2010, 01:57:05

I recorded a quick test, manually moving the joystick to change the pitch of the 'slave' oscillator :

http://www.louigiverona.com/webarchive/samzen/synth/audio/syncjoy.ogg

And a screenshot shows the transition from one sync-relation to another (top = base freq.), from 5 to 4 :

uncloned · January 16, 2010, 02:07:03

some interesting sounds here - especially about midway and on

Sam_Zen · January 16, 2010, 06:42:08

To me, the next interesting step is to survey the sub-frequency area, like the low pulse, the track starts with.
Thus, lowering the 'master' oscillator to this LFO region, and see, if the pulses have the same kind of divisions.

uncloned · January 16, 2010, 17:27:33

can you use your pulses to trigger something?

Sam_Zen · January 17, 2010, 01:09:33

Anything (almost)

uncloned · January 17, 2010, 14:32:26

this could be interesting!

I can see where having it drive percussion could work really well.

Have you tried multi-track recording in cool edit (or anything else) yet?

Sam_Zen · January 18, 2010, 03:24:56

When pulses are involved, percussion triggering is an obvious way to examine things.
The example was recorded with CEP, being the source of the screenshot.
(I like to refer to my MUX statement, about the sub-sonic area (< 16 Hz) being also part of the harmonic rules.)

As an example, I used the Casio SK1 sample kb with a sampled percussion sound set in a loop.
Meaning, if I press a key, the sound will be repeated at a certain speed, depending on the length of the sample.
Thus, if I press a key, an octave higher, the repetition will be twice as fast.

As an illustration, I've recorded the playing first with a brass sound, then the same sequence with the perc sample.
So I played the base note, then adding the octave, then adding the 5th in between, then replaced by the 4th.
Concerning the rhythm, the 5th has a ratio of 3:2, the quart is doing 4:3.
http://www.louigiverona.com/webarchive/samzen/download/oggs/sub_chords.ogg