Sounds are stored in groups inside DAT files. There are four of them (additional are in American Revolt):
SOUND-0.DAT SOUND-1.DAT ISNDS-0.DAT ISNDS-1.DAT
Those are packs of VOC files. You can extract single VOC files with any
ripper tool (ripper5, mrip, ...) or specific extractor for Bullfrog games,
available here (this package includes source to compile with GCC):
Download Bullfrog games WAVE/VOC Sound extractors
All extracted VOC files, converted to WAVE are available in "Sound gallery" section.
The game also contains MIDI file with in-game music, but because it uses strange sound bank, it is hard to play this file (I mean it sound strange). That's why "Sound gallery" section contains music extracted to WAVE.
On Mac version, all music themes (MIDIs) are stored in separate files, so it should be easier to play them. Mac version also includes a file that seems to be a sound bank for those MIDIs (PC version uses probably a internal bank).
VOC files in best quality can be found in special version of Syndicate for SB16, which is included on Syndicate Plus CDROM.