I believe there is also the danger of exasperating scruples by saying one should always go to confession if there is a distant and remote chance of mortal sin (there is always a possibility, but they often border on the insane), but from the sounds of this you might be a bit of a novice to the formation of your conscience. I think the best guide to this is to go to confession and work out either laxity or scruples over time until you do not have to ask questions like this here, but from the facts you state I would say at worst there is venial sin (or likely less) unless there are more facts such as knowingly and deliberately listening to the noises for sexual gratification, etc.
I think having scruples is a much lesser evil than laxity (though maybe having a very minor and slight laxity is better than a horribly severe case of scruples). Both states are sinful and prevent God’s grace from best flowing through you. If you are obsessed with trying to control every last detail about your life, the devil will make you obsess over the morality of little details and fill you with anxieties. If instead you like to take thing easy and not stress, he will do otherwise. You need to seek that middle ground.
Anyhow, I would repent of anything you are aware was wrong, confess, mention your uncertainty, and try to keep the same confessor. I find it beneficial if the confessor knows your identity so he can help judge your laxity or scrupulosity, but that’s up to you. Also read up on the Church’s doctrine of mortal sin (read it honestly not interpreting it too strictly or too leniently).
