:o Erm, actually, I haven't got to that bit in the ATPL notes yet ravenx! If I had, I'd probably be more certain than I am. But this stuff mostly comes from background reading. I always thought that v.p. props were all to do with maintaining engine power, the same as the gearbox in a car. Then someone told me that's not the case, although it's a common mis-conception. So I did some reading to find out the truth.
As for noise, lower engine speed (i.e. coarser pitch) will always generate less noise. This is due to a combination of both the engine and the prop being quieter at lower speeds.
(The extra engine noise due to the increase in throttle that you'd need to get the same thrust would be minimal. And that's if you increased the throttle at all - you might not want to because of the damage it would do to the engine using high throttle at lower speeds, you might just not bother because you've got enough power anyway, or you might be at full throttle and not have any extra to give!)
FFF
--------------