The tolerance is for the bearing angle. It gives a +/- angle compared to the bearing angle. For example, you want to trigger an alert if the driver comes from an angle og 120 degrees +/- 30 degrees. The tolerance will be 30.

Note: bearing angles are not implemented yet in any GPS...

EPE does not support audio alert yet, but I guess you will only have to specify a link to an MP3 or WAV file in the Link field.