Stabilize your LEDs or else....

Sounds unlikely, especially the USB case.

On a sunny day (Tue, 10 Aug 2021 08:19:32 -0700) it happened snipped-for-privacy@highlandsniptechnology.com wrote in snipped-for-privacy@4ax.com:

I have a set of PC speakers on a Sitecom USB hub, but the LED on that hub can only be seen from above, very small hole. Fluctuation due to the 3TB harddisk on the same hub is likely more.

Now managing to recover from the fluctuations of that LED the data the R/W head is reading from your disk *that* will be something :D :D.

I'd suspect that those people are really seeing vibration. That would be easy to test.

Easier to just observe a laser spot on any surface in the room, then listen to vibrations of the speckle as seen in a de-focused telescope. That was found by some guys trying to detect lab-rat heartbeats at cm range, and found they could use it to hear audio at km range.

A PMT, connected into the vertical input of an old analog oscilloscope, can trace the hillside-profile shapes of objects held in front of the screen. That's fun to play with.