Dataset specification · Pilot scale
50 hours of Malayalam Scripted Speech
A pilot scale build of 50 hours of Malayalam scripted speech. Proving that the specification survives contact with real speakers before anyone commits a budget to it. Speakers read prompts from a phonetically balanced script shown one line at a time, with retakes on any flubbed or misread line.

- Volume
- 50 hours
- Scale
- Pilot scale
- Per speaker
- 20–30 minutes of accepted audio per speaker
- Accepted yield
- 85–90% of recorded time is accepted
How Malayalam scripted speech is captured
Speakers read prompts from a phonetically balanced script shown one line at a time, with retakes on any flubbed or misread line.
A 45-minute booth session yields roughly 300–400 prompts. One file per utterance, cut at the prompt boundary, so alignment is exact before any forced-alignment pass runs.
Yield at this style: 85–90% of recorded time is accepted. Prompt-level retakes catch problems inside the session, so very little is discarded afterwards. This is the highest-yield style we run.
The specification
| Field | Value |
|---|---|
| Language | Malayalam (ml-IN, Malayalam) |
| Volume | 50 hours |
| Equivalent | 100 speakers at 30 minutes each, or 50 speakers at one hour each |
| Speech type | Scripted Speech |
| Per speaker | 20–30 minutes of accepted audio per speaker |
| File granularity | One WAV per prompt, named by prompt ID and speaker ID |
| Prompt coverage | Triphone-balanced script with digit, date, name and domain-lexicon blocks |
| Leading/trailing silence | 200 ms padded, verified automatically on every file |
| Alignment | Prompt text is ground truth; deviations are flagged rather than silently corrected |
| Dialects | Thiruvananthapuram, Kochi (central), Malabar / Kozhikode, Thrissur |
| Transcription | Verbatim, native-speaker, second-pass reviewed |

Designing the script for Malayalam
- Script built for triphone coverage rather than word coverage, so rare phone contexts appear often enough to train on
- Digit strings, dates, currency and person names blocked separately, because these are where deployed ASR actually fails
- Domain lexicon injected from your product vocabulary when you supply one
- Sentence-length distribution spread deliberately, since all-short prompts produce a model that cannot handle long utterances
- Built against Malayalam specifically: One of the most consonant-dense Indian languages; long geminates and clusters raise word error rates sharply
- Code-mixing handled explicitly rather than edited out — Manglish is standard in urban and professional speech, with heavy English noun and verb insertion.
Running a pilot scale Malayalam build
Three to four weeks from signed specification. Recruitment is the critical path, not recording — the studio time itself is under two weeks.
Two batches: a 10-hour first batch in week two so you can run it through your pipeline while the rest is still recording, then the balance on completion.
Budget higher transcription effort per audio hour for Malayalam than for Hindi; speech rate and morphology make it slower to annotate.
| Parameter | At this volume |
|---|---|
| Cities | One, usually the densest pool for the language — Kochi, Thiruvananthapuram |
| Studios | A single treated room |
| Recruiters | One coordinator |
| Speakers | ~100–120 |
| Sessions per day | 6–8 |
| Team | 1 coordinator, 2 engineers, 3 transcribers |
Cohort design
At 50 hours the cohort is deliberately simplified: two or three dialect groups rather than the full spread, with quotas enforced in aggregate. A build this size cannot support per-cell targets and should not claim to.
Requires literate speakers comfortable reading aloud in the target script, which is the main constraint on cohort breadth and has to be actively counterweighted.
| Dimension | Typical split | Why it matters for Malayalam |
|---|---|---|
| Gender | 50 / 50 | Pitch range differences change acoustic model behaviour; unbalanced cohorts bias recognition |
| Age | 18-25: 30%, 26-40: 40%, 41-60: 30% | Older speakers retain conservative Malayalam forms that younger urban speakers have lost |
| Region | Kerala / Lakshadweep / Puducherry (Mahe) and others | Dialect spread across 5 recognised varieties |
| Education | Mixed, including below-graduate | Prompt-reading fluency correlates with education and skews prosody |
| Condition | Studio / quiet room / field | Match the noise profile of your deployment |
Malayalam-specific considerations
- One of the most consonant-dense Indian languages; long geminates and clusters raise word error rates sharply
- Manglish is standard in urban and professional speech, with heavy English noun and verb insertion.
- Central Kerala news-reading dominates public data. Malabar and southern varieties, and fast conversational speech generally, are missing.
Quality gates for scripted speech
- Prompt-to-audio match verified by a native reviewer; a misread line is a rejected file, not an edited transcript
- Hyperarticulation flagged — a speaker over-enunciating because they are reading produces audio that does not match deployment
- Clipping and truncation checked at both utterance boundaries
- Per-speaker prompt coverage confirmed, so no speaker silently skips a block
- Old vs new script (chillu characters, Unicode normalisation) mixed within a dataset
- Fast speech leads to dropped-word transcription errors without a second-pass QA
100% content QA. At this volume there is no reason to sample, and a pilot exists precisely to surface specification problems.
What goes wrong on scripted speech sessions
- Reading voice: flat prosody and unnatural stress that trains a model on speech nobody actually produces
- Prompt fatigue in the back half of long sessions, where accuracy drops and pace flattens
- Speakers who are not fluent readers, which quietly biases the cohort toward higher education bands
- Script leakage across speakers, producing a corpus that memorises sentences instead of covering sounds
Risks at pilot scale in Malayalam
Cost at this band is driven by: Fixed setup cost is amortised over very few hours, so the per-hour rate is at its highest here; Narrow demographic requirements bite hardest at small cohort sizes.
- The specification itself is usually the risk, not delivery — pilots exist to find the clauses that do not survive contact with real speakers
- A single-city cohort will not represent the language nationally, and reading pilot results as national is the most common mistake at this band
- Malayalam carries 5 recognised varieties across Kerala, Lakshadweep, Puducherry (Mahe), so the quota matrix is wider than the headline volume suggests
- Central Kerala news-reading dominates public data. Malabar and southern varieties, and fast conversational speech generally, are missing.
Deliverables
- WAV audio to your naming convention, with the per-file manifest
- Verbatim Malayalam transcripts with utterance-level timestamps
- Prompt ID mapped to every utterance
- Verbatim deviation flags where the speaker departed from the script
- Per-utterance SNR and duration in the manifest
- Per-speaker metadata: age band, gender, region, dialect, education band
- Consent records mapped to speaker IDs
- QA report with pass rates, rejection reasons and agreement statistics
- Speaker-disjoint train / dev / test splits on request
What this trains, and what it does not
- ASR acoustic model baselines
- TTS voice building where a single speaker is recorded at depth
- Pronunciation lexicon and G2P validation
- Forced-alignment and phone-boundary work
Scripted audio contains no disfluencies, no false starts and no natural turn-taking. A model trained on it alone degrades sharply on real spontaneous input, so it is a baseline layer rather than a complete training set.
Frequently asked
Is 50 hours of Malayalam enough?
Enough to validate a specification, benchmark a vendor and produce a small evaluation set. Not enough to move a production model's error rate.
Why scripted speech rather than another speech type?
ASR acoustic model baselines, TTS voice building where a single speaker is recorded at depth, Pronunciation lexicon and G2P validation are what this style is the right input for. Scripted audio contains no disfluencies, no false starts and no natural turn-taking. A model trained on it alone degrades sharply on real spontaneous input, so it is a baseline layer rather than a complete training set.
How long does a pilot scale Malayalam build take?
Three to four weeks from signed specification. Recruitment is the critical path, not recording — the studio time itself is under two weeks. Two batches: a 10-hour first batch in week two so you can run it through your pipeline while the rest is still recording, then the balance on completion.
What does 50 hours of Malayalam scripted speech cost?
Quoted per delivered hour against this specification. At this band the drivers are fixed setup cost is amortised over very few hours, so the per-hour rate is at its highest here and narrow demographic requirements bite hardest at small cohort sizes. Send the spec and you get one fixed figure.
How much QA is applied at this volume?
100% content QA. At this volume there is no reason to sample, and a pilot exists precisely to surface specification problems.
Quote this Malayalam dataset
50 hours, scripted speech, Malayalam — pilot scale. Adjust anything and send it.