A common export of PowerPoint decks that contain voice narration is to make the slideshow into a video. This way, the viewers do not need the PowerPoint program or a (free) app to view the slideshow. The resultant video format is well-supported that any computer can play them. This is how many tutorials are made for Youtube.
You would make the narration directly with PowerPoint with these sound clips embedded onto the slides. The duration of each narration would likely be different. Therefore, you have to tell PowerPoint how long it displays each slide to allow the entire audio clip to play before PowerPoint transitions to the next slide. If you don't set the individual timing of each slide, PowerPoint gives each slide 5 seconds regardless whether the audio has finished playing.
To set custom durations for slides, click on the Transition tab in PowerPoint.
On the overview column on the left, select any slides that you don't want this default 5 seconds.
Put the cursor over the embedded audio clip. When the playback bar appears, hover the cursor over the end of the clip to get a pop up showing the length the audio clip.
Go to the top to put in the elapsed time before PowerPoint automatically shows the next slide. In this example's case, this slide is set at 53 seconds because the audio clip is 52 seconds.
