Dataset specification · Evaluation cohort
500 speakers of Marathi Scripted Speech
An evaluation cohort build of 500 speakers of Marathi scripted speech. Speaker-count-driven work: verification, diarisation and accent robustness, where breadth matters more than hours. Speakers read prompts from a phonetically balanced script shown one line at a time, with retakes on any flubbed or misread line.

- Volume
- 500 speakers
- Scale
- Evaluation cohort
- Per speaker
- 20–30 minutes of accepted audio per speaker
- Accepted yield
- 85–90% of recorded time is accepted
How Marathi 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 | Marathi (mr-IN, Devanagari) |
| Volume | 500 speakers |
| Equivalent | 250 hours at 30 minutes per speaker |
| 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 | Standard (Puneri), Varhadi (Vidarbha), Marathwadi, Konkani-influenced coastal Marathi |
| Transcription | Verbatim, native-speaker, second-pass reviewed |

Designing the script for Marathi
- 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 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.
Running an evaluation cohort Marathi 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.
A representative Marathi cohort should be split roughly 40% western Maharashtra, 25% Vidarbha, 20% Marathwada, 15% Konkan rather than concentrated in Pune.
| Parameter | At this volume |
|---|---|
| Cities | Three to four — Mumbai, Pune, Nagpur, Nashik, Aurangabad |
| Studios | Four rooms |
| Recruiters | Four coordinators |
| Audio yield | ~250 hours at 30 minutes per speaker |
| Sessions per day | 25–30 |
| Team | 1 programme lead, 4 coordinators, 8 engineers, 14 transcribers, 2 QA leads |
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.
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 Marathi |
|---|---|---|
| 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 Marathi forms that younger urban speakers have lost |
| Region | Maharashtra / Goa / parts of Karnataka and others | Dialect spread across 6 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 |
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.
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
- ळ vs ल substitution by Hindi-trained transcribers
- Anusvara placement varies between conservative and modern orthography
100% technical QA, 15% content QA, plus mandatory duplicate-speaker detection across cities.
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 evaluation cohort in Marathi
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
- 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.
Deliverables
- WAV audio to your naming convention, with the per-file manifest
- Verbatim Devanagari 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 500 speakers of Marathi enough?
Enough for reliable per-dialect evaluation and for training speaker-verification and diarisation systems.
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 an evaluation cohort Marathi 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 Marathi scripted 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 Marathi dataset
500 speakers, scripted speech, Marathi — evaluation cohort. Adjust anything and send it.