Please be aware that Safari on iOS 9 has a bug that leaves audio muted permanently, so you will not hear any audio in your games on iOS 9. This issue appears to have already been identified by Apple. Please help raise awareness of the issue by adding yourself to the CC list in this bug report:
(The webkit bug tracker does not have a voting system, so to prevent a flood of comments please just add yourself to the CC list which means you'll also get email notifications when the bug is updated.)
The good news is we have identified a workaround, and should have a beta release out shortly that includes this workaround. Note however that unless Apple fix this bug - and their track record with our previous reports is that they do not fix bugs until next year's release, so be prepared for this case - then you will need to republish all existing iOS content with the next beta release to ensure audio playback works.
We apologise for the inconvenience with this, but we must emphasise it is a bug in iOS 9, not Construct 2. I will update this thread as we have more news.