I have one as well, and I've noticed that area proximity detectors (in hallways used to detect presence/motion) do get picked up and come through as loud pops.
How loud? These are audible to me without an implant (unless some are audible and some are inaudible)
You might be hearing a relay, which is itself switched by the proximity sensor.
There are also electricity poles with a strong EM field that cause a humming sound.