Reading order is essential for people with no movement or limited movements in their hands or who use wands, switches, or sticks to access their computer-and screen reader users. When you create slides, putting the objects in a logical reading order is crucial for screen-reader users to understand the slide. This will ensure users can scan or tab through all the slide elements in the order you intended.
From the Home Ribbon select "Arrange."
Hit the "Selection Pane..." from the Drop-Down Menu.
Order the reading selection by dragging.
For the screen reader to properly speak the slide to the user, the options must go from top to bottom. Then press the “Selection Pane." This differs from how a visual user would hear or see the slide's layout. However, you can give all the users the same experience right from the "Selection Pane; you can drag and drop items to the new location (remember it reads from the bottom up). You want to click and drag the title to the bottom of the "Selection Pane" (it reads from the bottom up). Another way to do this is by using the backward arrow on the actions pane menu bar. It will stay open as you navigate from slide to slide as you make your corrections. Manually checking the reading order of your slides can be your last step before publishing your slides.
The highlighted objects is what the screen reader will read aloud.
In this example the Southern New Hampshire University logo would be "Picture 13" and would be read last.
Images and icons will need to have alternative text (alt. text) for the image/icon to be read to screen readers users. You can find how to add alt. text from How to Add Alternative Text (Alt. Text) to PowerPoint (Desktop Mac)