[Red Badger]

Mine is constant, 24-7-365, noises like a thousand crickets in the room at all times............

[CivilWarBrewing]

You can test with frequencies to see if yours can be changed. I try frequencies such as this: http://www.youtube.com/watch?v=rWE_gqWG7xE CAREFUL WITH THE VOLUME ON THIS ONE!

[silverleaf]

mine got better with lipoflavinoids (various spellings)

easy enough to try

[peteyd]

I guess crickets is a good description.
I tell people it sounds like bacon and eggs sizzling away.
Always with a food analogy.