I was quiet most of the time during all three of my labours, but not because I am stoical in any way, but just because I found that the pain drove me into my head. It definitely wasn't a conscious decision and I don't think I was being brave in any way.
I was quite vocal during second stage with ds1 (which lasted 1.5 hours) and got told by the senior midwife, "If we were putting half the effort into pushing that we are putting into making that noise, we could push this baby out right now!!" That helped (not!).
AuntiePickleBottom - it seems ridiculous to me that you seem a) to be expecting everyone to be able to labour the same way as you did, and b) want to assume that most women make lots of noise in labour, based solely on the evidence of a handful of filmed births.
Everyone is different, and everyone copes differently with labour - and your OP is a deliberate attempt to wind up and offend people. If you had asked, "Does it help the pain of labour to make lots of noise?", I suspect you would not have been called a troll.