I haven't encountered this in Nehrim or, IIRC, Oblivion, but that sounds like something I've encountered before in a few other games - from more than one developer - when they tried to access sound files that were corrupt or which they couldn't find (not sure which). It's very jarring and loud and sounds like heavy radio fuzz (KZZHHT!). It's hard to say for sure, though, as I understand it to be the case that Oblivion can be very finnicky when it comes to how sounds are played.
If it is a problem with the sound files themselves, a few questions that could help narrow down which ones: Does the sound play constantly or are there breaks in it? Does it occur anytime kobolds are nearby or only when they see you/attack you/are hit? Finally, do you know if the scamps in Oblivion have exhibited the same problem since your most recent installation of the game?