This thing is really annoying and I cannot believe that there hasn't yet been an option to turn it off. I hate the "chhh" sound everytime something appears on the screen. Also, there should be an option to turn off the pop sound that comes on when someone enters/leaves the pits or joins the server. Please include this in the next patch.

Quote from Scawen :

Quote from Becky Rose :

@Scawen, when you do rewrite the audio can you make the message beep configurable please - and by configurable, I meen let me turn it off

I think you can safely rename the sound files in data\snd folder.

Message.raw
SysMessage.raw
InvalidKey.raw

etc...

This workaround should suffice for now.