Did you just get the "Playback permissions" error dialog while using Spark Video editor in Safari? Here's the error dialog that you'd have encountered:
And here's what you can do to fix it:
- Go to Safari -> Preferences -> Websites -> Auto-Play
- Under "Allow websites below to automatically play media", for spark.adobe.com - choose "Allow All Auto-Play"
- Exit Preferences
- And now audio should work just fine!