An alternate suggestion would be to provide some kind of a warning that there is audio that will open automatically as a courtesy to those who might click onto the post. This could be done in several ways, the easiest being an icon that indicates that the post has audio that will open automatically upon clicking onto the post. This could be set up so the icon would go to the table of contents page regardless of where the audio is located on the thread. Or, there could be a color code so that the page number with the audio would be a different color (if it is just one page, it would also be color coded).
Doing that would give people fair warning that, if they click onto the page, it will start playing something with audio. This will give people a chance to lower the volume or mute it, or not click on the page. It would also preserve the right for people to include such material (so long as the audio and/or video do not contain objectionable material) that is pertinent to the post topic.