How to properly serve a file via a wrapper.

Please help. I thought I had this squared away, but apparently not. I need to be able to use a php wrapper to serve a file stored outside the web root. Works great for downloads / images - but my wrapper seems broken for media files to be played. My wrapper: http://www.shastaherps.org/bugs/rdb_audio.phps Demonstration of issue: http://www.shastaherps.org/bugs/wrapperBug.html What am I missing??