Hi there,
Avoid overlapping audio in the project. If at all you need overlapping audio, read the article Adobe Captivate audio for iPad.
If you use overlapping audio, then please check this article from the help file on 'best practices for creating projects for I-pads':
http://helpx.adobe.com/content/help/en/captivate/using/publish-project s-html5-files.html
Thanks.