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Dataset specification · Production scale

500 hours of Marathi Spontaneous Speech

A production scale build of 500 hours of Marathi spontaneous speech. The point at which a corpus is large enough to train a deployable model rather than adapt someone else's. 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 — 500 hours of Marathi Spontaneous Speech
Volume
500 hours
Scale
Production scale
Per speaker
25–40 minutes of accepted audio per speaker
Accepted yield
60–70% of recorded time is accepted
01

How Marathi 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.

Production scale — what the build is actually made ofCitiesFive to sixStudiosSix rooms plus two mobi…RecruitersSix coordinators under …Speakers~1,000–1,200Sessions per day40–50 nationallyTeam1 programme lead, 6 coo…
02

The specification

FieldValue
LanguageMarathi (mr-IN, Devanagari)
Volume500 hours
Equivalent1,000 speakers at 30 minutes each, or 500 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
DialectsStandard (Puneri), Varhadi (Vidarbha), Marathwadi, Konkani-influenced coastal Marathi
TranscriptionVerbatim, native-speaker, second-pass reviewed
Data visualisation of studio and field recording coverage across India — supporting 500 hours of marathi spontaneous speech
Data visualisation of studio and field recording coverage across India
03

Designing the topic bank for Marathi

  • 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 Marathi specifically: Retains the retroflex lateral ळ, which has no Hindi or English equivalent and is frequently substituted with ल by non-native transcribers
  • Code-mixing handled explicitly rather than edited out — Mumbai and Pune speech mixes Marathi, Hindi, and English in the same sentence. Marathi-only recordings collected in Pune under-represent the Mumbai reality of tri-lingual switching.
04

Running a production scale Marathi build

Eight to twelve weeks. Cities are staggered rather than started together, so the protocol corrections found in the first city are applied before the last one begins recording.

Six to eight batches, fortnightly, each speaker-disjoint so you can train on early batches without contaminating a later evaluation split.

A representative Marathi cohort should be split roughly 40% western Maharashtra, 25% Vidarbha, 20% Marathwada, 15% Konkan rather than concentrated in Pune.

ParameterAt this volume
CitiesFive to six — Mumbai, Pune, Nagpur, Nashik, Aurangabad
StudiosSix rooms plus two mobile rigs for rural capture
RecruitersSix coordinators under one programme lead
Speakers~1,000–1,200
Sessions per day40–50 nationally
Team1 programme lead, 6 coordinators, 12 engineers, 25 transcribers, 3 QA leads
05

Cohort design

At 500 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 Marathi
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 Marathi forms that younger urban speakers have lost
RegionMaharashtra / Goa / parts of Karnataka and othersDialect spread across 6 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

Marathi-specific considerations

  • Retains the retroflex lateral ळ, which has no Hindi or English equivalent and is frequently substituted with ल by non-native transcribers
  • Mumbai and Pune speech mixes Marathi, Hindi, and English in the same sentence. Marathi-only recordings collected in Pune under-represent the Mumbai reality of tri-lingual switching.
  • Available Marathi speech data is dominated by standard Puneri read speech. Vidarbha, Marathwada, and coastal Konkan varieties are severely under-collected, which is exactly where deployed voice products lose accuracy.
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
  • ळ vs ल substitution by Hindi-trained transcribers
  • Anusvara placement varies between conservative and modern orthography

100% technical QA, 10% content QA stratified by city, dialect, transcriber and recording condition, with automatic escalation to 100% on any failing batch.

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 production scale in Marathi

Cost at this band is driven by: Field and rural capture ratio — mobile rig hours cost more than studio hours; Rare dialect quotas, where the last 10% of the cohort can cost as much as the first 40%.

  • Speaker duplication across cities becomes a real risk at this cohort size and needs active de-duplication against voice and ID
  • Rural capture depends on weather and travel in a way studio work does not, so mobile-rig batches carry schedule variance
  • Quota drift compounds across six cities unless demographics are reconciled weekly rather than at the end
  • Marathi carries 6 recognised varieties across Maharashtra, Goa, parts of Karnataka, so the quota matrix is wider than the headline volume suggests
  • Available Marathi speech data is dominated by standard Puneri read speech. Vidarbha, Marathwada, and coastal Konkan varieties are severely under-collected, which is exactly where deployed voice products lose accuracy.
10

Deliverables

  • WAV audio to your naming convention, with the per-file manifest
  • Verbatim Devanagari 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 500 hours of Marathi enough?

Enough to train a deployable model for a single language, or to substantially improve a multilingual one. This is the most common production band.

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 production scale Marathi build take?

Eight to twelve weeks. Cities are staggered rather than started together, so the protocol corrections found in the first city are applied before the last one begins recording. Six to eight batches, fortnightly, each speaker-disjoint so you can train on early batches without contaminating a later evaluation split.

What does 500 hours of Marathi spontaneous speech cost?

Quoted per delivered hour against this specification. At this band the drivers are field and rural capture ratio — mobile rig hours cost more than studio hours and rare dialect quotas, where the last 10% of the cohort can cost as much as the first 40%. Send the spec and you get one fixed figure.

How much QA is applied at this volume?

100% technical QA, 10% content QA stratified by city, dialect, transcriber and recording condition, with automatic escalation to 100% on any failing batch.

Quote this Marathi dataset

500 hours, spontaneous speech, Marathi — production scale. Adjust anything and send it.

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