Exactly this! I made a lot of noise through my labour with DD. At first it was low pitched, and into transition it became louder and a little bit more scream-like, but it wasn't about the pain - it was my way of coping, of trying to be 'bigger' than the pain of the contraction if that makes sense. As noisy as I was through the contractions, once it was over I was very quiet - barely spoke a word in fact. We all cope in different ways.
Makes so much sense! I mentally refer to it as yelling over the top of the pain so I couldn't "hear" it.