I'm just trying to build a KF8 mobi file with embedded audio but get the message
"Audio Object is not supported on KF8".
I read that Kindle don't allow embedded audio through their Kindle Direct Publishing website but allow larger customers (Publishers) to directly bypass that restriction.
It seems a pity as it's such a big market.
I also read this:
which seems to indicate that it might be possible but it might use the Whisper Sync feature and then the audio is not embedded.
I just found another link
that says this:
Mobi – Amazon’s standard format for Kindle books does support audio and video content although the Kindle Direct Publishing (KDP) system will not accept Mobi files with audio or video. To upload your enhanced Mobi files to Amazon you will need to access a wholesaler account, which is usually restricted to larger publishers (we do not offer this service).