Waiting Room - Playing Audio Files

There is no way to just play audio, but you can now show a video with audio to those in the waiting room. You can find out more in the How to customize the Waiting Room section of this article: https://support.zoom.us/hc/en-us/articles/115000332726-Waiting-Room

Hope that helps and please make sure to mark the solution as accepted if this information is what you needed.

As far as we have found out, someone in the waiting needs to activate sound. So it may be worthwhile to mention that, even if it were a static view iso a video.