Since you say nozzle (and you're from the UK), I assume this is a canister filter. When you say there are no bubbles coming out, I assume there is water coming out. As long as there's water flowing, you are fine. If there isn't any water moving, have you primed the pump? You will have to do that on most if not all canister filters. The filter will push water out once it is to the pump but it can't suck it in. It should have a primer handle where you pump it to pull water through.
Complete silence is fine. That's what I love about my Fluval filters. If it weren't for the plants moving, you'd never know the filters were on.