Is it possible to include
itemprop="name" and itemprop="contentURL" in the same element?
as in the example bellow :
echo '<li itemscope itemtype="http://schema.org/AudioObject" >';
echo ' <a itemprop="name" itemprop="contentURL" href="http://wave.cat/music/'.$song['file'].'">'.$song['name'].', '.$song['artist'].'</a>';
echo '</li>';