vocalisation is encouraged in calmbirthing. It is when you start to get that high pitched mouth breathing types of panicky screams that it means you are losing control. Low pitched moaning is often seen as a sign birth is eminent and can help the focus at that time. Calmbirthing is all about the breathing and the visualisation to maximise the release of endorphins, the body natural pain killers which are tens times as powerful as any opiates...if you wanna scream in amongst it all go for it!!