Whatever happened to those weird noises affecting nearby speakers when we received a call on a cell phone back in the days, as illustrated in the link?



I was appreciating the nice little attention to that detail in gta4, but it got me wondering how come it’s gone nowadays.

In: Engineering

Only 00’s bois will remember, or however kids are talking these days.

The cell phone transmits quite a bit of RF energy when it is talking to the tower. That energy can leak into the amplifiers in a stereo system and disturb their operation, creating the sound you hear.

I don’t know exactly what happened, but I would guess they fixed this issue by:

– shielding the stereo amplifiers better (metal box)

– adding RF filters to the amplifier inputs

– making opamps with better RF rejection (basically built-in filters)

Something like the above. I would also hazard a guess that there are probably a lot of stereos floating around where this still isn’t fixed.

The band of the radio spectrum in use might have changed as we switched from GPRS / 2G to 3G and onwards. Higher frequencies being needed to transmit more packets of information at a faster rate.

Commenting to follow, I have a Yamaha music keyboard that’s 9 years old that makes sounds if I get a call when it’s close. The speaker makes the sound before the ringtone even starts

Microphones do this that are not connected to speakers (monitored with headphones). Leads me to believe it’s the input device catching signals, not the output.

Source: I own a recording studio.