I've had similar problems, but in 1.96. The sound scripting was ok, it was possible to access the sound by using a trigger, and the .lip-files moved the units lips as they should when they get the say-command... But no sound.
Not until I raised the volume of the sound to extremely high levels in the description.ext could I hear it.
nothing happened at db +18...
... nothing at +36...
... +72...
... etc...
Somewhere around db +150 OFP reacted. Then the sound came roaring out of the speakers at full power. It seemed as if OFP gave me all or nothing, and my theory is that OFP simply cannot handle a sound if the volume is too low. Am I right or wrong? I don't know, but after that i started recording my sound files with higher mic input, and since then I've never faced the problem again. (I use a good sound card and have the latest drivers btw.)