This is probably the easiest way. You can add the wav files (or whatever
format) as a slide transition sound. This will cause it to play at the
beginning of each slide.
Of course you could also add it to the animation timeline, but this is a tad
more difficult to understand. You will need to add error handling and such.
----Start Code-------
Sub Tommy()
'Assuming that all the sounds are ##.wav format
' starting at 1.wav and running thru 32.wav
Const SoundFileLimit = 32
'Assuming they are all in the same directory
Const SoundPath = "c:\sounds\"
Dim oSld As Slide
For Each oSld In ActivePresentation.Slides
oSld.SlideShowTransition.SoundEffect.ImportFromFile _
SoundPath & CStr(Int(Rnd() * SoundFileLimit ) + 1) & ".wav"
Next oSld
End Sub
----End Code-------
How to open the VBE window (using code in PowerPoint)
http://billdilworth.mvps.org/opening_the_vbe.htm