I knocked on the door to ask them if they've been hearing the low frequency motor/fan/machine vibration noise and/or if they installed anything the past weekend. An old lady opened the door and just kept saying no, before shutting the door really quickly. =.=
I think she thought I was selling something. Definitely doesn't speak english.
Blargh. Fired off an email to our HOA management folks, maybe they can help.
The noise is irritating and makes me frustrated.