Yes, that would work, except that for the slide to transition automatically,
you must also specify a time (e.g., Automatically after: 3 seconds).  And
since each page is of different duration, times can range from 2 seconds to
20 seconds.  I could record the amount of time it takes for each page and
enter those times; however, I have over twenty books completed now which
would require days of timings.  I was hoping for a global solution (if one
exists).  Thanks for the quick input.

Ute,
 Kiosk mode was the key solution.  That prevented him from advancing slides
with mouse clicks before audio was finished.  One other problem however, is
that he has visual impairment, and cannot navigate a mouse to click on a
button for advancement.  To solve this problem, I created a large transparent
box (full screen) that appeared after the audio finished.  I have a button
box that can be assigned to any key (or mouse click) that he operates.  So
now, after the audio is finished, he simply pushes the button (activating a
mouse click) at his leisure, and the slide advances to the next.  Perfect!  
Vielen dank!
Bitterphile