Noise, let me see now, after having been there twice and another trip a long 121 days away, I will try to give you my best impressions of what noise I heard.
An occasional snore, water lapping at the beach front, waves crashing onto the beach, the breeze gently rattling the palm fronds, some laughter from the pool area or just about any area, once in a while a cheer from the volleyball or other games taking place, a snore which invokes laughter, quite conversations, pages turning on books, birds singing, the singsong chant of the few vendors who get to walk up and down the beach, the melodies being played by some of those vendors who entertain for a tip (not bad), the red flag girl asking what it was I wanted to drink, my wife telling me to make certain I have suntan lotion on, occasional airplane flying into or out of the little airport across the road, some boat noise, some jet ski noise, people having a good time at the beach bar, the whirl of the cocktail mixer, and the sound of the hammock swaying gently back and forth. If that is noisy, then yes it is a noisy place, but in a tropical relaxed paradise.
Just back from CN last Tuesday. No kids at all at the side resorts. Vendors, very few and they are at the waterline (Cigars, Cigarettes and another one with dresses are all I remember). Strolling musician every now and then. However, there were WAVES. Water was a bit murky due to the storms that happened earlier in the month (Hurricane Nicole) but still beautiful and warm. At one point, a wave was so huge, it knocked me off my float and I lost my sunglasses . As the week went on, I noticed that the water was getting clearer and the waves were minimal. Wish it were earlier in the week when I lost my sunglasses, I could have probably found them! As a matter of fact, we cancelled the Catamaran cruise because a few of us get seasick and we were afraid that the waves would make us sick. I do have to tell you we love it all and will be back! As far as the rest of the noise, we were probably the ones making it - laughing and have a great time!
Speaking in relative terms... of course the cliffs are going to be more quiet and have less vendors than Bloody Bay. There is no beach on the cliffs and therefore no vendors walking along the edge of the properties.
That being said, again in relative terms, CN's beach (Bloody Bay) has less activity than CSA's beach (Long Bay), but neither are too noisy in my opinion.
One other thing that you don't have at the Cliffs...a Couples Resort and a Couples experience.
Go and enjoy. Couples and the Negril beach will give you a vacation to remember. (And a relatively quit one at that.