I think its our upstair neighbour that's been making this noise. Recently there's been a regular thumping noise with a low rumbling noise in between suggesting that its some sort of machinery. Its starting to get really annoying and is really affecting my mother who has trouble with sensitive ears towards low frequency sound. I'd like to complain but I wasn't sure how to do this. Is there any steps and measures I could take? Is it even possible to complain about it if they're working the machine during the day from 7-11pm? Also, I'm not exactly sure WHICH upstairs neighbour, but I'm guessing that its the one directly above us.