Dataset specification · Programme scale
1,000 hours of Malayalam Conversational Speech
A programme scale build of 1,000 hours of Malayalam conversational speech. Training from scratch in a language where no adequate public corpus exists. Two speakers hold an unscripted conversation seeded with a scenario, recorded on separate channels so overlap and turn-taking survive into the delivered files.

- Volume
- 1,000 hours
- Scale
- Programme scale
- Per speaker
- 20–30 minutes of accepted audio per speaker, in pairs
- Accepted yield
- 55–65% of recorded time is accepted
How Malayalam conversational speech is captured
Two speakers hold an unscripted conversation seeded with a scenario, recorded on separate channels so overlap and turn-taking survive into the delivered files.
A 45–60 minute paired session with both speakers on isolated microphones, either in adjacent treated rooms or split-mic in one room with bleed measured and logged.
Yield at this style: 55–65% of recorded time is accepted. Overlap regions, crosstalk bleed and one-sided stretches all cost delivered time. The lowest-yield studio style we run, and priced accordingly.
The specification
| Field | Value |
|---|---|
| Language | Malayalam (ml-IN, Malayalam) |
| Volume | 1,000 hours |
| Equivalent | 2,000 speakers at 30 minutes each, or 1,000 speakers at one hour each |
| Speech type | Conversational Speech |
| Per speaker | 20–30 minutes of accepted audio per speaker, in pairs |
| Channels | Two, one per speaker, never mixed down before delivery |
| Channel isolation | Bleed measured per session and logged; sessions over threshold are re-recorded |
| Overlap | Preserved, timestamped and labelled rather than edited out |
| File granularity | Per-channel session WAV plus a turn-level manifest with speaker IDs |
| Dialects | Thiruvananthapuram, Kochi (central), Malabar / Kozhikode, Thrissur |
| Transcription | Verbatim, native-speaker, second-pass reviewed |

Designing the scenarios for Malayalam
- Scenario seeds rather than scripts — a disagreement to resolve, a plan to make, an experience to compare
- Pairing designed deliberately: familiar pairs produce natural interruption, stranger pairs produce polite turn-taking, and you need both
- Scenarios that invite disagreement, because agreeable conversation produces almost no overlap to train on
- Register mixed across pairs so the corpus is not uniformly formal
- 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 programme scale Malayalam build
Twelve to sixteen weeks. This is a programme with its own governance rather than a project — weekly demographic reconciliation, a standing protocol review and a named counterpart on your side.
Ten to twelve batches, fortnightly, with a formal acceptance test per batch. Rejected batches are re-recorded rather than patched, so schedule contingency is built into the plan.
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 | Eight to ten — Kochi, Thiruvananthapuram, Kozhikode, Thrissur, Kannur |
| Studios | Ten rooms plus four mobile rigs |
| Recruiters | Ten coordinators, two regional managers, one programme lead |
| Speakers | ~2,000–2,400 |
| Sessions per day | 70–90 nationally |
| Team | 1 programme lead, 2 regional managers, 10 coordinators, 20 engineers, 45 transcribers, 5 QA leads |
Cohort design
At 1,000 hours the quota matrix is enforced per cell, not in aggregate. Every dialect, age and gender combination carries its own target and is signed off individually before final acceptance, because an aggregate 50/50 split can hide a cell that was never filled at all.
Effectively doubles recruitment load, since speakers are booked in matched pairs and a single drop-out cancels the whole session. Plan on 20–25% over-recruitment.
| 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 conversational speech
- Channel bleed measured on every session and rejected above the agreed threshold
- Diarisation labels verified against the isolated channels rather than inferred from the mix
- Turn boundaries and overlap regions checked by a native listener
- Speaking-time balance per pair audited, so a dominant speaker does not silently halve the session's value
- 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% technical QA, 7% content QA stratified across every axis, plus a blind 1% re-transcription audit measuring inter-annotator agreement across the whole programme.
What goes wrong on conversational speech sessions
- Crosstalk bleed that makes clean per-speaker training targets impossible to recover afterwards
- One speaker dominating, leaving a pair that delivers half the expected audio
- Unnatural politeness between strangers, producing clean but unrepresentative turn-taking
- Scheduling attrition — both speakers have to show up, so no-show rates compound rather than add
Risks at programme scale in Malayalam
Cost at this band is driven by: Programme management overhead, which is real at this scale and should be quoted explicitly rather than hidden in the hourly rate; The tail of rare dialect and demographic quotas.
- Transcriber consistency across a 45-person team is the dominant quality risk and needs continuous calibration, not a one-time briefing
- Speaker pool exhaustion in smaller cities, where the genuinely available cohort is finite
- Specification drift over three months as your model team learns what it actually needs — build a change-control step in rather than pretending it will not happen
- 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
- Speaker-turn segmentation with start and end timestamps
- Overlap regions marked with participating speaker IDs
- Backchannel and interruption markers
- Per-pair relationship metadata: familiar or stranger
- 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
- Speaker diarisation
- Meeting and multi-party ASR
- Turn-taking and endpointing for voice agents
- Speaker separation and target-speaker extraction
Two-party conversation does not generalise to multi-party meetings with four or more speakers, where overlap statistics change substantially. Specify that case separately.
Frequently asked
Is 1,000 hours of Malayalam enough?
Enough to train from scratch in a single language, or to build a strong multilingual foundation across a language family.
Why conversational speech rather than another speech type?
Speaker diarisation, Meeting and multi-party ASR, Turn-taking and endpointing for voice agents are what this style is the right input for. Two-party conversation does not generalise to multi-party meetings with four or more speakers, where overlap statistics change substantially. Specify that case separately.
How long does a programme scale Malayalam build take?
Twelve to sixteen weeks. This is a programme with its own governance rather than a project — weekly demographic reconciliation, a standing protocol review and a named counterpart on your side. Ten to twelve batches, fortnightly, with a formal acceptance test per batch. Rejected batches are re-recorded rather than patched, so schedule contingency is built into the plan.
What does 1,000 hours of Malayalam conversational speech cost?
Quoted per delivered hour against this specification. At this band the drivers are programme management overhead, which is real at this scale and should be quoted explicitly rather than hidden in the hourly rate and the tail of rare dialect and demographic quotas. Send the spec and you get one fixed figure.
How much QA is applied at this volume?
100% technical QA, 7% content QA stratified across every axis, plus a blind 1% re-transcription audit measuring inter-annotator agreement across the whole programme.
Quote this Malayalam dataset
1,000 hours, conversational speech, Malayalam — programme scale. Adjust anything and send it.