title: Filter folders that do not contain any audio files with bash
body: <p>Given a root folder, how do I filter down subfolders that do <strong>not</strong> contain any audio files (mp3, wav and flac)? Do I need to set a variable like</p>
  <pre><code>folders = find /parentfolder/ -type d
  </code></pre>
  <p>and then pass some expression on <code>${folders}</code> or is there a one-liner for this?</p>