Animation effects come up later than the synced-audio

Hello,

I'm creating some e-Learning of Asian languages.
When viewing LMS in my iPad Air, slide contents (e.g. Graphics, Textbox which are sync-animated with the audio) show up and fade out with no delay, however, they become delayed in my iPad2.

Even after the audio playing ends, the animation effects sometimes does not start at all.

(None of the slide contents show up.)

This problem does not happen in English e-Learning.

I'd like to know the solution, and why the delay occurs only in Asian languages.

Machine environment

- Windows 7 64bit
- PowerPoint 2007
- Articulate13 Update2 1402.2817

Regards
Hiroki