How to add a voiceover to a presentation or slide deck

Narrated slides — for a course, an async update, a sales deck sent instead of presented live — need a voice that's clear, consistently paced, and timed to fit. Text-to-speech is a natural fit because you can iterate on wording for free before generating anything.

Script per slide, or one continuous script

Either works: write one script per slide and export separate clips to time against your slide transitions, or write the whole narration as one script with pauses marking slide changes, then split the final audio in your video/deck tool. Insert pause at each transition point gives you a clean, exact marker either way.

Fit to time for exact slide durations

If a slide needs to land at exactly 30 seconds — matching an animation or a fixed transition — Fit to time stretches the render to your target duration without changing pitch, as long as the target is reasonably close to the natural read length. Useful for keeping narration in sync with a deck that has fixed timing.

Background music, used carefully

A subtle bed under presentation narration can make it feel more produced — pick something calm (not upbeat) and keep the volume low; with duck under voice on, it drops further whenever the narrator is speaking so it never competes with clarity. For information-dense slides, consider no music at all — clarity usually matters more than atmosphere.

One consistent voice throughout

Pick one voice and quality tier for the whole deck and keep it — consistency across slides matters more for presentations than for almost any other format, since the audience hears the same "presenter" for the whole runtime.