My labor with DS2 began gradually and built slowly. I was well rested, and felt strong and controlled throughout. Once my contractions began to require more focus, I began to hum through them, letting the sound really resonate in my skull. DS2 is a hummer and seems to do it to calm himself and when he is deeply engrossed in an activity.
My most recent birth was five months ago. Labor was quick and intense, coming on hard and lasting a quick 2.5 hours from start to finish. Feeling like I was ahead of the contractions just wasn't a priority for me and I let myself scream to the heavens as much as I wanted to. DD is sweet as can be but she is a screamer! She has these explosive squawks she uses when she's extremely happy, for EC and also when she's uncomfortable.
I ran the theory by DH yesterday as DD was happily squawking. I expected that he'd just humor me but he's on board. He said 'Yes! She does sound like you. Three of screeches like that and she was born!'