+++ This bug was initially created as a clone of Bug #20890 +++
As the track element may be used inside an audio element and as the track element can be used to provide subtitles, it would be great to have a poster attribute in the audio element, so, the image linked in the poster attribute would be display as background image in the "screen" (box) where the subtitles are displayed.
Thanks for your interest on that topic.
<video> already supports this, no?
Agree - I closed the bug for public-html and the person who registered it seemed to be ok with the existing solution through <video>.