For me, not loud but many times very intense, with headshaking, body shaking, etc. to the point where many times I am asked afterwards, "Are you OK?". Well, yes, but just give me a couple of minutes.
I have been with a lot of guys in the last 35 years, but three stand out in my memory.
In my late college days, one guy told me when we got to my apartment that he was very loud and to just put a pillow over his mouth if he got too loud. Sure enough as I was topping him, he started screaming.... and I did put a pillow over his mouth so as not to disturb my neighbors. I was convinced I was just that good, and he was in ecstasy because of my sexual prowess.
Or maybe he did that with all the guys. We tried it a number of times with just the same result.
Another guy had such intense orgasms when standing, in addition to the heavy breathing, he would actually get weak in the knees when he came. I had to hold him up or gently let him slump to the floor for a few moments until he recovered.
And the most unusual of all for me, for all the many guys I have been with, was a guy I dated a few years ago. Tall, masculine, subdued, very deep voice, sang bass in the choir, big dick. When he was approaching orgasm, he would emit a high pitched squeal, continuous until after he came. The first time it happened I was just shocked. I had never run into that before or have never since. It was hard to believe that his voice would be able to emit such a high pitched, piercing, continuous squeal. I must say it was very off putting and distracting. I would have laughed, except I had great respect for him and did not want to cause him any embarrassment. We never discussed it and subsequently stopped dating for other reasons, but it happened every time we had sex.
Just goes to show, what variety there is in the human being and our experiences.