I'm not entirely certain as to what you mean by this Ivar. Are you referring to Clairaudience, which refers to hearing spirits or astral beings...? If this is the case, I'd recommend exercising your chakra's and performing more meditation. Such simple things can go quite a long way when it comes to that sort of thing.
Something I would always do is just try to focus on my hearing and shut out my other senses when meditating. Focussing on your hearing and listening skills, picking up on tone inflections and the like will all give you a better experience and exercise what might be dormant clairaudient abilities.
For me personally, I've been a Clairaudient since I was a child but I had to keep exercisingit in order to be able to hear things, otherwise, I'd most likely lose the ability. I think of Psychic abilities like muscles, if you don't work on them and keep them strong then they'll fade into the backgroundand end up much weaker than they would have been. Granted, they'd still be with you as it is a skill, but they'd just be harder to use.
Also, there is no tricks or tips to master something quickly. Everything worth having takes hard work and perseverance. I suggest reading books on the topic or doing exercises for the ability specifically.