Problem(s) involving timeline and audio echoes in Storyline 360 when using text-to-voice

Just thinking out loud here... assuming you've published your course (either to LMS or Web), you could try replacing the "damaged" audio file published with the course (again, assuming there's some distortion occurring at the time of publication) with the original audio file:

If you're unfamiliar with how to do this, there are some things to keep in mind:

- Since SL gives unique identifiers to each item, you may need to spend a bit of time opening and listening to individual audio files until you find the one you want to replace.  These should be located in the story_content folder.

- Once found, drag and drop the original audio file into the story_content folder.  Then, copy the unique file name given to the compressed audio file to the clipboard.  Once copied, delete the compressed audio file.  Rename the original audio file by applying the unique name you copied earlier.  Continue to do this for all audio files (a pain, I know, but it might just do the trick!)

I'd be curious to see if that helps.