low audio for HTML5 output in Internet Explorer

I'm attempting to troubleshoot a problem for one of my trainees when they view my HTML5 output in Internet Explorer. This information is coming from them and since they're in another city, I can't personally verify any of it nor get my hands on their notebook to check it out.

They're saying that when viewing a published HTML5 file, the audio in Internet Explorer so low that it's difficult to hear what's being played. If they view the file in Chrome or Firefox then the audio plays at the correct level. My first thought is that they possibly have the audio slider for IE turned down, but they're saying that audio for anything else in IE, such as YouTube, plays at the correct level.

Does anyone have any ideas about what could possibly be causing the problem?