DOS software that use redbook audio soundtracks games require an audio cable be connected between the disc drive and the sound card, and as mentioned the physical CD needs to be inserted into the drive.
As of now there's no software solutions to mount a disc image in pure DOS and get CD audio like you can in Windows/DOSBox, there's only hardware solutions like PicoGUS and ZuluIDE.
98/DOS Rig: BabyAT AladdinV, K6-2+/550, V3 2000, 128MB PC100, 20GB HDD, 128GB SD2IDE, SB Live!, SB16-SCSI, PicoGUS, WP32 McCake, iNFRA CD, ZIP100
XP Rig: Lian Li PC-10 ATX, Gigabyte X38-DQ6, Core2Duo E6850, ATi HD5870, 2GB DDR2, 2TB HDD, X-Fi XtremeGamer