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Heard a strange sound a couple of times last week while web browsing. It sounded very much like I was listening to someone's microphone (e.g. the sound was static-y, it sounded like papers were rustling and then music was playing, etc.) but the sound ended abruptly, without me touching anything. I couldn't investigate it before it ended, and I couldn't see anything in any of my tabs that indicated something had played. It also definitely did not sound like an ad....

Researching the problem a bit, I've seen something similar reported relatively frequently, with the explanation being that the person's speakers or headphones had picked up some AM radio signals, a baby monitor, etc. The small catch is that I only ever saw external speakers or headphones being discussed, rather than laptop speakers. My question, then, is whether the speakers being a laptop's internal speakers would make a significant difference, e.g. due to being more "insulated".

I'd very much like to chalk up what I experienced to an explainable physical phenomenon rather than, for example, a trojan that has evaded all of my anti-malware scans somehow. Figured that here seemed like an appropriate place to ask, though if I've misjudged this and another place would be better, I'd be happy for suggestions.

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  • $\begingroup$ Has happened to me. I had an external monitor that had built-in speakers. Needless to say, I no longer own this monitor. $\endgroup$ – GisMofx Feb 23 at 11:44
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For people who live near an AM radio transmitter, getting demodulated AM audio bleeding into another circuit is a common experience. The most common cause is poor grounding of the equipment that is picking up the radio signals. The easiest way to defeat it is by making certain that the chassis ground of the equipment is well-connected to the ground terminal of the AC mains supply plug, and that the ground terminal of the AC wall outlet is, in fact, tied to the main ground (a copper-clad rod pounded into the ground near the master circuit breaker box for the house).

Poor or zero electrical contact with the ground rod will turn the house wiring into an antenna, and havoc will thereby be wreaked. This is especially true for clamped (and loose or corroded) ground connections, because then the bad contact point can behave like a lossy diode, and demodulate the AM signal.

Missing or miswired ground lines are common in older houses that date back before around 1970 and are distressingly common in houses from the 1940's and 1950's.

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  • $\begingroup$ Thanks for the response! I don't think it would be the house, though. The house was built sometime in the 90s, and this is the only time it has been a problem, and even then it was only briefly so. I guess it's feasible that it could be the laptop not being grounded, though, since I definitely don't have it set up in any way to explicitly ground it (just using it normally, plugged into my desk and charging). $\endgroup$ – FilmCoder May 29 '20 at 21:16

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