If you mean the RISC OS 'beep' then this can be altered (within limited parameters) from the command line. It's so long since I have played with the RISC OS sound system that I have forgotten the commands.
I have had a few users report a problem when VirtualRPC starts up. The machine emits one or two blasts of white noise. This appers to be a bug in MacOS X. I asked several users to see of other apps caused the same problem. I have now had reports of white noise blasts from iTunes. Hopefully apple with fix this asap if it's reported to them.
This article:
http://www.virtualacorn.co.uk/support/a ... /index.htmcovers the va.cfg file.