Noise

Could you tell if maybe you've been coming out of trance abruptly during these meditations? Sometimes if you're so focused on completing them, it could be the case that you don't give yourself enough time to return to your normal state.

I'd suggest spending a few extra minutes grounding yourself afterwards and seeing whether that helps.

Still, if loud noises are causing you actual pain several hours later, I'd recommend getting your hearing checked as well, by a doctor. We shouldn't assume it's necessarily related to something of a spiritual nature.

If you enter in the trance you must come out from it after the meditation session and also ground yourself.

Hello. What do you mean exactly by October rituals and how would you describe the loud noises? Where do they seem to come from and what do they sound like? This information is helpful in order to try to find out what could it be.