Timepilot2084

Forgive me if I'm posting in the wrong area, I didn't see a Commodore 64 specific thread, but I'm using a stupid tablet and it's possible I overlooked it. I have a question regarding the use of digitized sound effect and speech on the C64. I'm pretty familiar with programming, and have even made several games using BASIC with ML subs, but I can't figure this one out. Why is it that some games can play digitized audio over two voice music without stopping all the on-screen action, but some stop all sprite movement and audio before playing the sample? For instance, Way of the Exploding Fist has no trouble playing the digitized samples during the action. Thanks for reading!