i had a similar instance. when i was younger ~10 i remember waking up scared by a nightmare around midnight. i decided i’d go to my sisters room because she was likely still up and i didn’t want to wake my parents.
her room was on the second floor so i had to quietly run in the dark and up the stairs as to not disturb my parents.
when i got to the steps i began hearing a crowd of people and with each step up the stairs it got louder and louder. i recall it being one of the loudest things i’ve ever heard. at the landing of the stairs it was so loud i collapsed onto the door handle and swing it open. then just like that the noise stopped and it was silent.
my sister was up watching a movie and looked over curious to why i made such a dramatic entrance. i don’t recall ever saying anything i just curled up on her floor watching a movie until i fell asleep.
i’m in my 30s and i still think about that event at least once a year and it still gets my heart pumping! thankfully it has never happened since.
certainly sounds like a fair explanation! don’t you just love how our brain works?