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Market analysis

Why do AI models underperform on Indian languages?

Updated 2026-08-01 · 4 min read

Studio-grade voice recording session for text-to-speech training data — illustration for: Why do AI models underperform on Indian languages?

Short answer

Indian-language models underperform mainly because of data, not architecture. Public corpora for most Indian languages are small, read-speech heavy, urban-skewed and rarely code-mixed, while real usage is conversational, dialectally varied and heavily mixed with English. Add script complexity, inconsistent transcription conventions across sources, and evaluation sets drawn from the same narrow distribution as training, and a model that looks strong on benchmarks fails on a call from a semi-urban user. The fix is targeted collection: spontaneous and conversational audio, dialect quotas that match your users, code-mixed material, and a held-out evaluation set recorded under deployment conditions.

Key takeaways

The argument at a glance1The gap is distributional: training data does not look like real usage.2Code-mixing and dialect variation are the two largest unmodelled factors.3Benchmarks drawn from the same narrow distribution hide the problem until launch.
  • The gap is distributional: training data does not look like real usage.
  • Code-mixing and dialect variation are the two largest unmodelled factors.
  • Benchmarks drawn from the same narrow distribution hide the problem until launch.

The public data problem

Most freely available Indian-language speech is read speech from a small speaker pool in a handful of cities. It is useful for bootstrapping and misleading as a proxy for deployment audio.

Coverage is also wildly uneven: the largest languages have order-of-magnitude more public data than languages with tens of millions of speakers, and dialect coverage inside each language is thinner still.

Code-mixing

Urban Indian speech mixes English continuously, and the switched tokens are usually the content words — amounts, product names, dates — that matter most to a product. Monolingual training data systematically fails on exactly these.

Two-speaker conversational recording session in a studio — market analysis context for Why do AI models underperform on Indian languages
Two-speaker conversational recording session in a studio

Evaluation that flatters

When the evaluation set is carved from the same recording sessions as training data, it shares speakers, rooms and devices. The score is real; the generalisation it implies is not. A separate deployment-condition evaluation set usually reveals a gap of several points.

What actually fixes it

Collect spontaneous and conversational audio in the dialects your users speak, include code-mixed material at realistic density, record over the channel you deploy on, and build a frozen held-out evaluation set with per-slice reporting. In our experience this sequence moves applied metrics faster than any additional volume of read speech.

Frequently asked questions

Why do AI models underperform on Indian languages?

Indian-language models underperform mainly because of data, not architecture. Public corpora for most Indian languages are small, read-speech heavy, urban-skewed and rarely code-mixed, while real usage is conversational, dialectally varied and heavily mixed with English. Add script complexity, inconsistent transcription conventions across sources, and evaluation sets drawn from the same narrow distribution as training, and a model that looks strong on benchmarks fails on a call from a semi-urban user. The fix is targeted collection: spontaneous and conversational audio, dialect quotas that match your users, code-mixed material, and a held-out evaluation set recorded under deployment conditions.

The public data problem?

Most freely available Indian-language speech is read speech from a small speaker pool in a handful of cities. It is useful for bootstrapping and misleading as a proxy for deployment audio.

Code-mixing?

Urban Indian speech mixes English continuously, and the switched tokens are usually the content words — amounts, product names, dates — that matter most to a product. Monolingual training data systematically fails on exactly these.

Evaluation that flatters?

When the evaluation set is carved from the same recording sessions as training data, it shares speakers, rooms and devices. The score is real; the generalisation it implies is not. A separate deployment-condition evaluation set usually reveals a gap of several points.

Related reading

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