paulriley wrote:gavriel, surely you could draw the same lines when comparing c4 with g4. They would still share the same high and low point wouldn't they? because the c5 doesn't "change" the c4.
But of course it does!
If we would have only a C4 (without a C5 compounded into it), it would look like a simple symmetric sinus wave. Primitively speaking, within one C4 cycle as marked with green on the picture the wave line would go upwards for a quarter of the cycle, then downward for another quarter reaching the starting level, the downwards for another quarter period and up again to the starting level.
However, in the compound wave form we have a line which goes up for a SIXTH of the (C4) cycle period reaching the same hight a regular C4 would reach after one FOURTH of a cycle, then (in the second sixth cycle) it goes downwards reaching the starting level, then (in the third sixth cycle) UP AND DOWN reaching the starting point AGAIN, then UPWARD AND DOWNWARD reaching the starting level AGAIN and finally deep downwards and then upwards to the starting level.
Thus in the compound waveform we have also one big top and one big bottom but the top is "earlier" (at the end of the first sixth rather than at the end of the first quarter) and the bottom is later (at the end of the fifth sixth).
Also in a non-compound sounds of a C4 and C5 the second tops of C5 would be as high as the first ones.
No other sound than C4+C5 will give exactly such a picture.
The compounding created the little bumps in such a way as to give the common denominator 12 within one big "C3" cycle. Buttt the C3 is not there and the G4 is not there either (there is no big huge top in the middle of the C3 period and the C3 period is not divided into three as it does in the natural G4 wave).
Figuratively speaking, the compound line is making minor snake-like movements to meat the ratios of a G4 without actually creating a G4 and this forces us to listen to periods of a C3 cycles to get repetitive scenarios BUT the C3 is not there either!