Tried playing Overseer but when I try to look at items, the subtitles flash for only a split second and Tex doesn't say anything. I can only examine items that can be picked up in the inventory. Being a veteran of Tex Murphy games, I know that you are supposed to be able to examine things when the mag glass appears. Does anyone have a tweek to fix this problem?

i had the same issue, sound in movies work, but no speech in game..
i tried it on a VM with XP and had the same problem.

i did however find out how to fix it.
you'll need to install Intel RSX 3D Audio. it is found on the original discs, but the only problem is that GOG does not include this in their installation at all, and the program is so old, you'll have to spend hours trying to locate a copy you can actually download, and even then it needs some coercing to get working.

after installing RSX 3D audio, you'll need to register the "RSX.dll" and "aaduio.dll" files with regsvr32 before the game starts working with speech..

So today is your lucky day, i have found a copy of RSX and made a quick batch file for DLL registration.
This has been tested and woking on winXP and win8 x64.
download the zip, run RSX setup and the fix. you may need to add the sharedll reg key if you have problems.
and check system32 and syswow64 (if x64) that rsx.dll and aaudio.dll are present before running the fix.

Download it here

edit 14/03/14: fixed broken link