How to Make a Generated Voiceover Sound Less Robotic

People often blame the voice when generated narration sounds robotic and switch from one to another looking for a better one. Sometimes a different voice does help. More often, the cause is in the text, and the same script in a better voice still sounds flat. Fixing the script is quicker, cheaper and more effective than hunting for the perfect voice.

This is a checklist of the changes that make the biggest difference, roughly in order of how much they matter. Work down it and re-listen after each one.

1. Break up long sentences

A voice has no breath to run out of, so it reads a long sentence at a steady pace to the end, which no person would. That relentless evenness is the strongest cue that a voice is synthetic. Cut long sentences in two or three, and the voice will pause, fall and restart as a person would.

2. Vary the sentence length

A run of sentences of the same length produces a drone. Mix them: a long one, a short one, a medium one. A very short sentence, such as that is the point, creates emphasis on its own. You are writing the rhythm into the script, and it is the one thing the voice reliably follows.

3. Write contractions

Formal written English avoids contractions, and spoken English is full of them. A script that says it is not, you will and do not sounds stiff, while it is not, you will and do not sounds natural once written as isn't, you'll and don't. Use the forms you would say aloud, unless the register of the video is deliberately formal.

4. Use punctuation deliberately

5. Fix the words it gets wrong

A single mispronounced word is enough to break the illusion. Listen for names, numbers, acronyms and any unusual term, and respell them phonetically in the script until they sound right. Nothing makes a voice sound more mechanical than a name said wrongly, and nothing makes it sound more human than a difficult word said well.

6. Pick the voice for the content

Voices differ in character, and a voice that suits one script is wrong for another. A warm, unhurried voice suits a story, a crisp neutral one suits a tutorial and a brighter one suits a quick explainer. Test your own script, not the sample sentence, with two or three candidates, and choose the one that sounds like a person who knows what they are talking about.

7. Adjust the speed slightly, if at all

The default pace is usually well chosen. A small adjustment, a few percent either way, can suit a particular script. Large changes sound unnatural quickly, especially speeding up. If the script is too long, cut it. If it feels rushed, simplify it. Reserve the speed control for fine tuning.

8. Finish in the edit

• Add a short pause, by hand, before a key point or a section change.
• Add a very quiet room tone under the voice, so silences are not dead.
• Place music beneath, at a low level, to give the voice a bed.
• Apply a light reduction of any harsh high frequencies, if the voice has them.
• Match the level to the rest of your audio.

Silence is the giveaway. A recorded voice is never perfectly silent between words, because there is always room sound. A little room tone underneath generated narration makes the pauses feel natural and removes the sense of a voice in a vacuum.

9. Listen like a stranger

The last test is to listen to the finished narration as though you had never seen the script, ideally a day later, on a phone speaker. Anywhere you notice the voice, rather than what it is saying, is a place worth another look. The goal is not to fool anybody. It is that the listener stops thinking about the voice and follows the content, which is what narration is for.