The best practice is to add closed captions or subtitles to your presentation. By enabling this feature, you are making your content more accessible to a larger audience, including people with hearing disabilities, different learning cognitive abilities, and those who speak languages.  There is also the added feature of Live Presentations in PowerPoint; audience members can see a presentation on their devices and read live subtitles in their preferred language while they speak. They can use "pinch to zoom" to see the slides more clearly on mobile devices, give feedback, send live reactions to the presenter, and navigate back to review previous slides.