Once you add an audio/sound track to your PowerPoint presentation, you can let the inserted audio span across all your slides from the first one to the last by selecting the Play across slides option. That’s great if you need the same music playing on all your slides. But what if you want the music to play only across some successive slides? What if you want the music to play from slide 1 to 12, and let all slides thereafter play without any music? Or you may want to add another audio clip for the next set of slides? Either way, it is possible to limit the number of slides that your music will play across.
Loop audio clips to play across specific slides in PowerPoint 2013 for Windows.

