[KevinH]

Some recommendations:

- make sure you are creating an epub3 not an epub2 as javascript can only work in epub3

- make sure javascript is enabled in Sigil Preferences.

- put all javascript into its own file to prevent issues with xml escapes with less than and greater than inline in an xhtml file

- create a link to your javascript file in head (or tell Sigil to link it)

- use Sigil's Add Existing... menu to add the audio and vtt files to your epub so they are properly included in the opf manifest. Use short simple file names.

Try to get it working in Sigil's Preview and use Sigil Preview's Inspector javascript console to debug any javascript issues.

If you run into trouble, create a sample epub3 with your javascript and the the worlds shortest transcript and mp3 and post it here and I will try to help get your short sample working for you.