Text-to-speech and voice for Indian languages
Making a computer speak an Indian language naturally is about more than sound quality. Names, numbers, consent for voices and misuse of voice clones all matter.
In 60 seconds
Text-to-speech and voice for Indian languages
Making a computer speak an Indian language naturally is about more than sound quality. Names, numbers, consent for voices and misuse of voice clones all matter.
What makes a voice good
| Quality | What it means | An example to test |
|---|---|---|
| Intelligibility | People can understand every word | Play it to listeners and ask them to write what they heard |
| Naturalness | It sounds like a person, with natural rhythm and stress | Does a question sound like a question? |
| Pronunciation | Words, names and borrowed English words are said correctly | Names of districts, rivers, people and schemes |
| Text normalisation | Numbers, dates, money and short forms are read the right way | "₹1,250", "12/08", "Dr.", a train number, a PIN code |
| Right register | The voice fits the setting: warm for a helpline, clear for an announcement | The same sentence in formal and friendly style |
Numbers and names are the hardest part
- Build a pronunciation list (a lexicon) for names that matter to your users: places, crops, medicines, schemes, people.
- Test code-mixed sentences. Does the voice say English words naturally inside an Indian-language sentence?
- Test scripts. Can it read the language when written in its own script, and does it do something sensible with Roman letters?
Judging a voice with people
- 1
Pick sentences
Real sentences from your app, including names, numbers and mixed language. - 2
Choose listeners
Native speakers from the regions and age groups you serve. - 3
Ask simple questions
"Write what you heard", and "How natural was it, 1 to 5?" (a mean opinion score). - 4
Collect problems
List every mispronounced word and wrong number reading. - 5
Fix and retest
Update the lexicon and rules, then test again with new listeners.
Voices belong to people
- Anyone can upload any recording and clone the voice
- Voice actors sign a vague form once, forever
- No way to tell the audio is synthetic
- Clear, recorded consent from the voice owner, checked before cloning
- Contracts that say where, how long and for what the voice is used, with fair pay
- Disclosure that the voice is AI-made, and content credentials or watermarking where possible
Watch and read more
Lab
A 20-sentence TTS test sheet for one language, with a listening plan.
The problem
Pick one Indian language you know well.
- Write 20 test sentences: 5 with numbers (money in lakh or crore, dates, phone numbers, PIN codes), 5 with names of places or people, 5 code-mixed sentences, and 5 everyday sentences in natural style.
- For each, write how it should be spoken, in words.
- If you can, try a free TTS tool on 5 of them. Do not upload anyone else's voice. Note any errors.
- Write a short plan: who will listen, how many listeners, and the two questions you will ask them.
You are done when
Hard questions
Try to answer before you reveal. If you can answer these, you understood the lesson.
Q1A voice sounds very natural but often says place names wrongly. Is it ready to ship for a railway app?Reveal
Probably not. In that app, place names carry the key information. A natural voice that says the wrong station is worse than a plain one that is correct. Quality must be judged on the words that matter for the task, not only on general naturalness.
Q2A user says they want to clone their late grandfather's voice from old family videos. What should a responsible product do?Reveal
This is a sensitive case. The grandfather cannot consent, and other family members may disagree. A careful product would have a clear policy, require proof of the right to use the recordings and agreement from the family members who hold those rights, keep the result private, mark it as synthetic, and allow it to be deleted. Many teams choose not to offer this at all. Where laws apply, take legal advice.
Questions people ask
What is a mean opinion score (MOS)?
Listeners rate audio, usually from 1 (bad) to 5 (excellent), and you average the ratings. It is simple and widely used, but it depends on who listens and what they compare against. Use native speakers and report how many listened.
Should an AI voice say it is an AI?
Yes, people should not be tricked into thinking they are talking to a human. A short disclosure at the start of a call or on the screen is a good habit, and rules in some places may require it.
Can I use a film actor's voice from YouTube to train a voice?
No. The voice belongs to the person, and the recording is usually copyrighted too. Use your own voice, a voice actor who has signed a clear paid agreement, or an openly licensed voice dataset that allows your use.
How do I stop my voice product from being misused?
Check consent before creating any cloned voice, limit who can create voices, log what is made, add disclosure and watermarks where possible, block known misuse, and give people a way to report abuse. No single step is enough on its own.
Lesson test
5 questions. Get 3 right (60%) to pass and complete this lesson.