hmm guud stuff

Bad idea, that'll greatly bloat the file size of the mod for no real benefit.
You need to add in loop cue flags to the sound. Free software I know of that are able to do that are GoldWave and Wavosaur. There should be tutorials online for how to do this, for Wavosaur in particular I remember it being an absolute breeze, just a few clicks in the right spot.

I would suggest making the sound longer, three times should fix the issue. Four for good measure.