Infrasound. Proven Possible (>100dB is absolutely harmful though, lower levels are object of studies now and testing on humans yielded inconclusive results) negative impact on people’s health and general wellbeing, waves travel quite far and have high penetration, and data centers are absolutely the source of it with all the fans and pumps.
Not saying that there 1:1 causation here, but having a data center around will absolutely make you miserable, and dizzy too.


So, you may have noticed that 5 GHz Wi-Fi has smaller coverage area than 2.4 GHz.
It works that way all the way down to infrasound, which is <20 Hz, and natural examples would be whale communications (thousands of kilometers) or volcano eruptions (infrasound wave from Krakatoa eruption lapped around entire globe multiple times).
As for human factors - basically any big industrial tech object is gonna be the source of ultrasound. So it’s kind of safe to assume that infrasound from data centers may be “heard” from at least several kilometers away. Dunno how it compares to refineries and power substations - but they’re also source of that.