Are you referring to white or pink noise (they are different) ?

kind of sounds like "Sshshshshshshshshsheeeeeeeeeeeeeee" Like a TV not tuned a channel.

Unless you have pressed a button that is labeled "pink noise" or "White noise" it usually means the thing in question is either

1) not tuned / calibrated (needs fixing)

or

2) broken (need fixing)

Pink noise it used for calibrating EQ and speaker system set ups.

I have never seen a pink noise generator intentionally incorporated into a guitar amp.