We may all flunk this since there seems to be a consensus, lol. there's an interesting Youtube video that someone posted the link to recently, don't recall which site. It seemed to dispel the widely held belief that 3U is louder than split and it'd be hard to dispute his results. He recorded both with the same arrow out of a recurve and overlaid the graphs of the decibel meter. The spikes were almost identical although one (I forget which) may have been slightly longer in duration. His conclusion, they're different sounds, but one's technically not necessarily louder than the other.