Earhiss?

[LadySegesta]

What is this earhiss sound you're supposed to listen to after vibrations? I've seen it mentioned around the forums a few times, but I myself have not heard this 'earhiss'. Is it supposed to sound similar to your ears popping or something? =/

[CFTraveler]

When you're in complete silence,  you can hear the high pitched sound from your ears.  This is only audible usually late at night when there isn't any ambient sound, but once you become aware of it you can hear it at other times.
That's the earhiss I tell people to listen to when they are doing some 'noticing', and the same Birm referred to in his 'triangle method'.