the only sound I hear is a slight hmmmmm. from 2 powerheads.. I dont like water splashing sounds.. but you can get rid of all of them.. 2 ways.
1. minimal water drop... ie. from overflow to sump drain less than 1".
2. air. keep everything under syphon. water wont make noise. but air bubbles in water makes lats of noise.
once you get your tank setup put another post about the noises you found and I can help you get rid of them.. no need to preplan for noises they can be rid of easily.