>>37264
There are annoying frequencies.
Like on CRT monitors and TVs which produce 15kHz.
Some pop songs use this too. They seem to add this high frequency (~16kHz) before the chorus/climax of a song.
Another is your screen monitors can literally read your mind. They detect frequencies of your brain. Say you're tired and sleepy, your monitor will surely sleep on you (during idle) but if you're not then the monitor won't accidentally sleep while you're awake and looking at it.