Play audio through a PowerPoint presetation

Set the music to play through the presentation
A .Right-click the sound's icon
B. Pick Custom Animation from the popup menu
The Custom Animation pane will open and your sound file should be listed.
C. Click the arrow directly to the right of the sound icon to pull down the various options.
D. Select Effect Options
E. Locate the Effects tab and Click the radio button beside Stop Playing after *** slides
Put 999 in the box so the track will play throughout all your slides, even if you go back and forth among slides.
PPT considers each transition a "slide," so you should put a large number in there.
F. Check the settings in the Timing tab. To play automatically, the timing should be set to Start. After Previous with a 0-second delay. Click OK to close the dialog box