Plugin concerned: WordPress Audio Player
Google was indexing my music posts with the ugly default description to get the Adobe player. Maybe the description is useful, but not for me.

When sharing on facebook, the same:

Quick Solution:
You can simply edit this in wp-content/plugins/audio-player/audio-player.php
Open the php file with your favorite text editor (advanced: line 1089) and search for this line:
You also need to have JavaScript enabled in your browser
Then replace the default text above the line to whatever you like. Like I did here:

Add keywords if you want. Anything is better for SEO than the adobe one. You may also leave a short “get adobe here” and “javascript required” just in case; for newbies.
Result: (same for google)