Lecture and talk audio
Staff training, online courses and self-advancing slide decks all need a voice explaining them. Record it yourself and every fluff means recording again; with TTS you fix one line of the script and re-render just that part. This guide covers making slide narration efficiently.
1. One file per slide
Rather than one file for the whole lecture, one file per slide is far easier to work with. When the content changes you re-render only that slide, and adding audio slide by slide in your presentation software is simple.
Putting the slide number in the file name — "03_safety-rules" — keeps the downloads in order. Tick several in the results list and use "Download selected as zip" to get them in one go.
2. Judging how much script you need
Thirty seconds to a minute per slide is usually about right. At default speed Korean TTS reads roughly 250–300 characters per minute. It varies with the voice and the sentences, so make one slide first, look at the length shown in the results list, and size the rest of your script from that.
| Target length | Script size (approx.) |
|---|---|
| 30 seconds | 130–150 characters |
| 1 minute | 250–300 characters |
| 3 minutes | 750–900 characters |
3. Voices that suit teaching
- Explanatory lectures: InJoon (male) or SunHi (female) with the "News" tone. Trustworthy and clear.
- Beginners or children: SunHi with "Clear" or "Gentle". Soft and approachable.
- The difficult passages: the "Crisp" tone slows things down and makes them easier to take in.
Keep the same voice across one lecture. Changing it from slide to slide is distracting.
4. Technical terms go in Pronunciation fixes
Training material is full of abbreviations and jargon. Register them once on the main screen and they apply to every slide.
The subtitles keep the original spelling (UPS, KPI), so the screen can show the abbreviation while the audio says it correctly.
5. Adding audio in PowerPoint
- Select the slide the audio belongs to.
- Insert → Audio → Audio on My PC, and choose the mp3 you downloaded.
- Select the audio icon, then in the playback settings turn on Start automatically and Hide during show.
- In the transition settings, set "After" to match the audio length and the lecture advances by itself.
Menu names differ a little between versions. Most other presentation tools, Google Slides included, add audio in much the same way.
6. Subtitles for accessibility
The subtitle file (SRT) behind the CC button drops straight onto a lecture exported as video. It lets people in offices where sound is awkward, and learners with hearing difficulties, follow along — well worth including in staff training material.
7. Training that needs a role-play
For safety training or customer-service practice where you need a conversation, use Script mode. Manager and new hire, staff member and customer — each role is read in its own voice and merged into one file.
8. An example script for one slide
Reading out exactly what is written on the slide makes screen and sound identical, which is dull. Keep key words on screen and let the audio expand on them.
That much runs about thirty seconds. If a slide goes past a minute, splitting it into two is easier on the listener.
Start with the script for your first slide. Check the length, then size the rest to match.
Make lecture audio