Control of Audio Playback in Presenter View in Keynote?
To get full playback controls in Presentation mode in Keynote, all you
  need to do is make the placed audio icon larger, then move your mouse
  into that larger region while in presentation playback mode. 



The controller is not visible while editing your presentation, so yust make it large square and then check in presentation view.


  As the size of the audio icon increases, you’ll see more and more
  control options when you hover over the region in presentation mode.
  Once you reach 400 pixels in size, you’ll see all the same controller
  features you get with a QuickTime movie.
  
  Note that when you’re in edit mode, you’ll see an increasingly-large
  version of the Sound icon as you increase its size. As with the
  standard-sized icon, though, this icon will not appear in presentation
  mode. To access the audio playback controls while in presentation
  mode, just move your mouse into the region of the large icon, and the
  controller will appear.
  
  Source: http://www.macworld.com/article/1142542/keynoteaudio.html