I've found with mine, it's the psu that makes most of the noise. The miner itself, is actually quieter, than my Avalon 841's.
Take a look at the thread below, for some sound control ideas, specifically for the M3. However, in your situation, being in
an apartment type area, ANY asic miner will be a noise problem. Goodluck!!!
Quote from Pangolinminer Thread:
https://bitcointalk.org/index.php?topic=2345436.msg32688389#msg32688389Actually I bought a PSU from amazon (I think it was Beleev.in) and my miner has been whisper quiet compared to the stock PSU, it's night and day difference. Can even keep it indoors without soundproofing. Also to the guy above, your freq might have to do with the PSU, i swapped mine out and its been working like a beast with best freq, could also be the amount of power the miner is getting, needs to be optimal.
Moderator's note: This post was edited by frodocooper to remove a nested quote and unnecessary whitespace.