Audio being cut off - HTML5 in mobile Safari

We have a course recently produced with a few full-screen graphics on each page and audio to match. However on mobile Safari, users are reporting that occasionally when navigating to a new page, the audio from the beginning of the page is being cut off. We've moved the audio on the timeline to start after a half second or second to help negate this issue, but users are still reporting that the beginning of audio (first couple words) is cut off sometimes.

Is this a matter of some mobile devices not necessarily having the memory needed to run HTML5 content smoothly? I have run into the same issue the odd time running in Google Chrome on my PC, but for the most part I can't seem to replicate this issue locally. Is it possible higher compression on videos and lower quality images would help? Right now both are set to maximum quality.

Thanks.