Download the
Walls of Bratock Sound Blaster Audio Pack [ZIP|362KB] and the here attached SBFMDRV.COM and CT-VOICE.DRV, unpack all archives to your game folder, run setup (if not done already), run SBFMDRV.COM (every time you play WOB in a new DOSBox session*), start the game, and be happy.
*Of course you can add it to the [autoexec] of the DOSBox.conf if you want, but in case of autoexec I would recommend to write a BAT to have it personalised (gamealised?) for WOB.