If your zone is defined by a collider it will work. Otherwise how exactly are you defining the zone? If it's something built into core Unity (reverb zone, etc), then it will work, otherwise probably not. As I said once you are outside the range of the Audio Source (based on its max distance), it will not be playing or audible. But it doesn't check for anything else like walls. However you could make it barely heard by also using our audio occlusion settings as well, or by "stopping all of that SFX" with a Trigger Enter elsewhere (with the Event Sounds script). Time scale does not affect our audio, but you have many ways to pause it in the API and our scripts.