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Dataset specification · Evaluation cohort

500 speakers of Malayalam Conversational Speech

An evaluation cohort build of 500 speakers of Malayalam conversational speech. Speaker-count-driven work: verification, diarisation and accent robustness, where breadth matters more than hours. Two speakers hold an unscripted conversation seeded with a scenario, recorded on separate channels so overlap and turn-taking survive into the delivered files.

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Two speakers recording natural conversational speech data — 500 speakers of Malayalam Conversational Speech
Volume
500 speakers
Scale
Evaluation cohort
Per speaker
20–30 minutes of accepted audio per speaker, in pairs
Accepted yield
55–65% of recorded time is accepted
01

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.

Evaluation cohort — what the build is actually made ofCitiesThree to fourStudiosFour roomsRecruitersFour coordinatorsAudio yield~250 hours at 30 minute…Sessions per day25–30Team1 programme lead, 4 coo…
02

The specification

FieldValue
LanguageMalayalam (ml-IN, Malayalam)
Volume500 speakers
Equivalent250 hours at 30 minutes per speaker
Speech typeConversational Speech
Per speaker20–30 minutes of accepted audio per speaker, in pairs
ChannelsTwo, one per speaker, never mixed down before delivery
Channel isolationBleed measured per session and logged; sessions over threshold are re-recorded
OverlapPreserved, timestamped and labelled rather than edited out
File granularityPer-channel session WAV plus a turn-level manifest with speaker IDs
DialectsThiruvananthapuram, Kochi (central), Malabar / Kozhikode, Thrissur
TranscriptionVerbatim, native-speaker, second-pass reviewed
Field recording session with a rural speaker in India — supporting 500 speakers of malayalam conversational speech
Field recording session with a rural speaker in India
03

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.
04

Running an evaluation cohort Malayalam build

Six to eight weeks. Speaker-count targets front-load recruitment, so the coordinator team is proportionally larger than an equivalent hours-based build.

Four batches, each one a demographically complete slice rather than a convenient chunk, so early batches are usable for training on their own.

Budget higher transcription effort per audio hour for Malayalam than for Hindi; speech rate and morphology make it slower to annotate.

ParameterAt this volume
CitiesThree to four — Kochi, Thiruvananthapuram, Kozhikode, Thrissur, Kannur
StudiosFour rooms
RecruitersFour coordinators
Audio yield~250 hours at 30 minutes per speaker
Sessions per day25–30
Team1 programme lead, 4 coordinators, 8 engineers, 14 transcribers, 2 QA leads
05

Cohort design

At 500 speakers quotas are enforced per dialect and reconciled fortnightly. Aggregate demographics are reported per batch so drift is visible while there is still time to correct it.

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.

DimensionTypical splitWhy it matters for Malayalam
Gender50 / 50Pitch range differences change acoustic model behaviour; unbalanced cohorts bias recognition
Age18-25: 30%, 26-40: 40%, 41-60: 30%Older speakers retain conservative Malayalam forms that younger urban speakers have lost
RegionKerala / Lakshadweep / Puducherry (Mahe) and othersDialect spread across 5 recognised varieties
EducationMixed, including below-graduatePrompt-reading fluency correlates with education and skews prosody
ConditionStudio / quiet room / fieldMatch the noise profile of your deployment
06

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.
07

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, 15% content QA, plus mandatory duplicate-speaker detection across cities.

08

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
09

Risks at evaluation cohort in Malayalam

Cost at this band is driven by: Cohort breadth and screening depth, not recorded hours.

  • Duplicate speakers across cities inflate the apparent cohort and quietly corrupt speaker-disjoint splits
  • Recruiting for breadth tempts coordinators toward the easiest available demographic, which needs weekly quota audit
  • 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.
10

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
11

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 500 speakers of Malayalam enough?

Enough for reliable per-dialect evaluation and for training speaker-verification and diarisation systems.

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 an evaluation cohort Malayalam build take?

Six to eight weeks. Speaker-count targets front-load recruitment, so the coordinator team is proportionally larger than an equivalent hours-based build. Four batches, each one a demographically complete slice rather than a convenient chunk, so early batches are usable for training on their own.

What does 500 speakers of Malayalam conversational speech cost?

Quoted per delivered hour against this specification. At this band the drivers are cohort breadth and screening depth, not recorded hours. Send the spec and you get one fixed figure.

How much QA is applied at this volume?

100% technical QA, 15% content QA, plus mandatory duplicate-speaker detection across cities.

Quote this Malayalam dataset

500 speakers, conversational speech, Malayalam — evaluation cohort. Adjust anything and send it.

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