Creative Labs released a new driver for the PCIe X-FI Titanium on March 7, 2014. There appears to be compatibility issue between this new driver and LotRO (at least there is on Windows 8.1 64-Bit, which is what I'm running); some of the sound effects stop working shortly after you enter Middle-earth, then may work sporadically for a bit, then will stop working altogether. Oddly enough, the music seems to continue to work okay.
The fix? Rollback to the previous driver, lol.
Hope this helps!