I bet it is weird! The whistle starts as soon as the "Powered by Unity" screen disappears (after I first click "Play!").

There are several kinds of
constant whistle :
- one for the selection screen,
- another one (A) with Left Brain when I have
not clicked on "Start Server", or if I have clicked on "Disconnect",
- another one (B) with Left Brain when I have clicked on "Start Server" but
not on "Disconnect".
I can switch from (A) to (B) at will when I click "Disconnect" or "Start Server".
Moreover, when playing Right Brain, the whistle
varies, as I mentioned before, and it seems to be correlated with the current point of view of the player.
What is even weirder is the sound can be heard without the speakers on. It seems to come from the PC. Could it be the CPU or the GPU card?