You can put it below or above.
It's quieter if you put it below, but you have to have a hole or a durso type setup to allow air to escape.
Another thing to make it quieter is to use a filter sock. That'll get rid of all the splashing sounds. Many people have the drain line above the water line in the sump and use the filter sock to muffle the splashing.
Personally I use the filter sock and have the drain line submerged and use a durso to allow the air to escape. It's basically inaudible. The bad part though is that half of your filter sock will be half submerged and as such you'll have to swap them out every 3-4 days.