[buildsjets]

When I was a kid, I could hear the sound the of the flyback transformer on the CRT TV from anywhere in the house. None of the adults could. 15.7 kHz. Now obsolete both due to the lack of CRTs, and degradation of my hearing from heavy metal concerts and jet engine exposure.

[brycewray]

Same here about the TV's flyback transformer. My parents always wondered how I could hear from down the hall (out of sight from the TV) when the horizontal hold or vertical hold went awry. :-)