Dolby last posted in this thread like a year ago, and saying all the sounds in the game suck isn't a great way to make friends and influence people.
Also, Tribes 2 was a commercial game, part of a family of sequels, and thus, well-funded and practically co-developed by a paying and involved community. It better have had good voice work, otherwise it would not have stood any chance against the Unreal or Quake dynasties (its real competition in the online team scifi shooter semi-tactical multimode circa 2000 game market).
Tremulous is a free, open source game. Please don't confuse yourself that there are anywhere near the same resources brought to bear on the respective projects.