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Dataset specification · Domain scale

250 hours of Malayalam Spontaneous Speech

A domain scale build of 250 hours of Malayalam spontaneous speech. Fine-tuning a production model for a specific domain, accent range or deployment condition. Speakers talk unscripted on prompted topics — describing a process, recounting an event, arguing a position — with a moderator who prompts but does not lead.

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Structured dataset packages ready for delivery — 250 hours of Malayalam Spontaneous Speech
Volume
250 hours
Scale
Domain scale
Per speaker
25–40 minutes of accepted audio per speaker
Accepted yield
60–70% of recorded time is accepted
01

How Malayalam spontaneous speech is captured

Speakers talk unscripted on prompted topics — describing a process, recounting an event, arguing a position — with a moderator who prompts but does not lead.

A 60-minute session covering six to eight topics, recorded continuously and segmented afterwards into utterances at natural pause boundaries.

Yield at this style: 60–70% of recorded time is accepted. Long silences, moderator speech and abandoned topics are cut in post, so recorded hours run well ahead of delivered hours. Budget for the gap.

Domain scale — what the build is actually made ofCitiesThree to fourStudiosThree to four rooms plu…RecruitersFour coordinators under…Speakers~500–600Sessions per day25–30 nationallyTeam1 programme lead, 4 coo…
02

The specification

FieldValue
LanguageMalayalam (ml-IN, Malayalam)
Volume250 hours
Equivalent500 speakers at 30 minutes each, or 250 speakers at one hour each
Speech typeSpontaneous Speech
Per speaker25–40 minutes of accepted audio per speaker
File granularitySession-length WAV plus segmented utterance files with offsets into the parent
SegmentationPause-boundary segmentation, reviewed by a native listener rather than left to VAD
Moderator channelRecorded separately and excluded from the delivered speaker audio
Disfluency conventionFilled pauses, repetitions and false starts transcribed, not normalised away
DialectsThiruvananthapuram, Kochi (central), Malabar / Kozhikode, Thrissur
TranscriptionVerbatim, native-speaker, second-pass reviewed
Diverse Indian speakers waiting for multilingual data collection sessions — supporting 250 hours of malayalam spontaneous speech
Diverse Indian speakers waiting for multilingual data collection sessions
03

Designing the topic bank for Malayalam

  • Topic banks graded by familiarity, so speakers across education and occupation bands all have something to say
  • Open prompts only — anything answerable with yes or no produces thirty seconds of audio and a stalled session
  • Culturally grounded topics per region, since a prompt that works in Mumbai can draw blank looks in Guwahati
  • Topic rotation across the cohort so the corpus does not over-represent a handful of subjects
  • 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 a domain scale Malayalam build

Six to eight weeks. Beyond three cities the bottleneck moves from recruitment to transcription throughput, which is why the transcriber count rises faster than the engineer count.

Four to five batches on a fortnightly cadence, sequenced so the dialects you care about most land first.

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
StudiosThree to four rooms plus one mobile rig
RecruitersFour coordinators under one programme lead
Speakers~500–600
Sessions per day25–30 nationally
Team1 programme lead, 4 coordinators, 8 engineers, 14 transcribers, 2 QA leads
05

Cohort design

At 250 hours 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.

Screening is for willingness to talk, not literacy, which opens the cohort to speakers a scripted protocol would exclude. Expect to over-recruit by 15% for speakers who freeze on the day.

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 spontaneous speech

  • Segment boundary review — bad boundaries produce truncated words that poison training more than they help
  • Disfluency transcription consistency audited across transcribers, since conventions drift fast on this style
  • Moderator speech confirmed absent from delivered segments
  • Topic distribution checked per speaker so one dominant subject does not skew the language model
  • 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 with stratified sampling across city, dialect and transcriber, so no single team's output goes unchecked.

08

What goes wrong on spontaneous speech sessions

  • Speakers who dry up after a minute, leaving sessions that look complete by duration but are mostly silence
  • Drift into a reading register when a speaker becomes self-conscious about the microphone
  • Moderator over-prompting, which turns a monologue corpus into an interview corpus
  • Transcriber normalisation — quietly cleaning up disfluencies destroys the exact signal this style exists to capture
09

Risks at domain scale in Malayalam

Cost at this band is driven by: Transcription depth — verbatim with disfluencies costs materially more than clean-read transcription; Number of distinct dialect quotas rather than raw hours.

  • Transcription becomes the critical path and stays there for the rest of the volume bands
  • Coordinator turnover mid-build causes quota drift that is only visible in the final demographic report unless it is audited weekly
  • 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
  • Filled-pause and false-start markers
  • Segment offsets into the parent session file
  • Topic label per segment
  • Speech-rate and pause-density statistics per speaker
  • 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

  • Robust ASR for real user speech
  • Language modelling on natural syntax
  • Disfluency detection and removal
  • Prosody and speech-rate modelling

Phonetic balance cannot be guaranteed — speakers say what they say. If you need specific phone contexts or a controlled lexicon, this style has to be paired with a scripted layer.

Frequently asked

Is 250 hours of Malayalam enough?

Enough to shift word error rate meaningfully on a domain-specific deployment. For a general-purpose model in a low-resource language, still a starting layer.

Why spontaneous speech rather than another speech type?

Robust ASR for real user speech, Language modelling on natural syntax, Disfluency detection and removal are what this style is the right input for. Phonetic balance cannot be guaranteed — speakers say what they say. If you need specific phone contexts or a controlled lexicon, this style has to be paired with a scripted layer.

How long does a domain scale Malayalam build take?

Six to eight weeks. Beyond three cities the bottleneck moves from recruitment to transcription throughput, which is why the transcriber count rises faster than the engineer count. Four to five batches on a fortnightly cadence, sequenced so the dialects you care about most land first.

What does 250 hours of Malayalam spontaneous speech cost?

Quoted per delivered hour against this specification. At this band the drivers are transcription depth — verbatim with disfluencies costs materially more than clean-read transcription and number of distinct dialect quotas rather than raw hours. Send the spec and you get one fixed figure.

How much QA is applied at this volume?

100% technical QA, 15% content QA with stratified sampling across city, dialect and transcriber, so no single team's output goes unchecked.

Quote this Malayalam dataset

250 hours, spontaneous speech, Malayalam — domain scale. Adjust anything and send it.

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