Rixasha: Good point. I haven't listened to them yet, and I certainly can't claim that I can hear the difference to high quality lossy compression, so I ran them though auCDtect 0.8.2 and here's what it thinks:

Eric Brosius - 01 - Irrational Games Logo
CDDA with probability 43%

Eric Brosius - 02 - Med Sci 1
CDDA with probability 100%

Eric Brosius - 03 - Med Sci 2
CDDA with probability 99%

Eric Brosius - 04 - Engineering
CDDA with probability 100%

Eric Brosius - 05 - Ops 1
CDDA with probability 100%

Eric Brosius - 06 - Hydro 1
CDDA with probability 100%

Eric Brosius - 07 - Hydro 2
CDDA with probability 100%

Eric Brosius - 08 - Ops 2
CDDA with probability 100%

Eric Brosius - 09 - Ops 3
CDDA with probability 100%

Eric Brosius - 10 - Command 1
CDDA with probability 87%

Eric Brosius - 11 - Command 2
CDDA with probability 100%

Eric Brosius - 12 - Command 3
CDDA with probability 100%

Eric Brosius - 13 - Rec
MPEG with probability 93%

Eric Brosius - 14 - Credits
CDDA with probability 100%

Eric Brosius - 15 - Intro Cutscene
CDDA with probability 100%

Eric Brosius - 16 - Cutscene 2
CDDA with probability 87%

Eric Brosius - 17 - End Cutscene
CDDA with probability 100%

So, with the unfortunate exception of track 13, it finds it likely that they are lossless in origin. It's significantly less confident with track 1, but that may be because it's so short.

GOG.com: Could you check if there has been a mistake with track 13?

EDIT: Out of interest I took a deeper look into track 13 and it looks strange. There's an end to the spectrum around 16kHz, which could well be why auCDtect thinks that something is missing, but surprisingly there is again significant amount of data above 20kHz. I'm not really familiar at all with this sort of thing and I guess it could be aliasing of some sort, but it could also be that auCDtect is wrong. A lot of the title contains speech from the game that sounds highly processed to begin with (perhaps even mp3 compressed?) and it could be throwing it off.