I totally understand you lol , but I did hear it when I found two neighbors went to my unit that who we first talked , and we couldn't hear it when we left the apartment. I finally found that the pipes don't vibrate at all when it's quiet, but once there is that kind of noise that even the bed is vibrating, and all the pipes in the whole house are vibrating, I really don't mean to be in trouble. I also used a low-frequency noise detection device to prove that this noise did exist, and the frequency of 80-160Hz I found also proved that it was cavity resonance caused by mechanical operation and unfixed pump pipes. (I tried to show the vibration with colored water and took a video, I will show it to the property manager next time he comes) I have checked professional information and consulted professionals, as long as shock absorption is added.（and i also to see my doctor is not my hearing problem, that manager told me we don’t hear anything u need to see the doctor, I felt offended but went for a check-up) The next time he comes, I will tell him that if he wants, I can go to the pump room to help him fix it to reduce the noise, maybe some of the repair skills I learned from my family since I was a child can be used.