We use CoPilot to navigate to campsites, many of which are on restricted or private roads. I've found the warning sounds very irritating when the route planner comes across these.

There is a simple way of suppressing them. If you look in the com.alk.copilot.euromarket.premiumeuwest/audio subdirectory, you will find a number of .wav files. One is called restricted.wav; another is silence.wav. If you rename restricted. wav to something else (eg xrestricted.wav), then make a copy of silence.wav and rename that to restricted.wav, the warning sounds will disappear.....

I suppose the same trick could be used for other irritating sounds......