I have version 4.4.5, OS is Windows 8.1, trying to use Impress
Hello LibreNovice, to attach a music file to your LibreOffice Impress slide show, you could do the following:
1) Select the menu "Insert : Audio or Video..."
2) in the File Chooser dialog, select your music file
3) a small picture representing your music file will appear in your Slide
4) and if you select that picture, then the Toolbar "Media Playback" becomes visible at the bottom of the window. There are the buttons for Play, Pause, Stop, etc.