Dataset specification · Production cohort
1,000 speakers of Urdu Spontaneous Speech
A production cohort build of 1,000 speakers of Urdu spontaneous speech. Generalisation across speakers, which is what actually drives real-world ASR robustness. Speakers talk unscripted on prompted topics — describing a process, recounting an event, arguing a position — with a moderator who prompts but does not lead.

- Volume
- 1,000 speakers
- Scale
- Production cohort
- Per speaker
- 25–40 minutes of accepted audio per speaker
- Accepted yield
- 60–70% of recorded time is accepted
How Urdu 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.
The specification
| Field | Value |
|---|---|
| Language | Urdu (ur-IN, Perso-Arabic (Nastaliq)) |
| Volume | 1,000 speakers |
| Equivalent | 500 hours at 30 minutes per speaker |
| Speech type | Spontaneous Speech |
| Per speaker | 25–40 minutes of accepted audio per speaker |
| File granularity | Session-length WAV plus segmented utterance files with offsets into the parent |
| Segmentation | Pause-boundary segmentation, reviewed by a native listener rather than left to VAD |
| Moderator channel | Recorded separately and excluded from the delivered speaker audio |
| Disfluency convention | Filled pauses, repetitions and false starts transcribed, not normalised away |
| Dialects | Dakhini (Hyderabad), Lucknawi, Dehlvi, Bihari Urdu |
| Transcription | Verbatim, native-speaker, second-pass reviewed |

Designing the topic bank for Urdu
- 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 Urdu specifically: Shares most phonology with Hindi but adds Perso-Arabic phonemes (/q/, /x/, /ɣ/, /z/, /f/) that many speakers merge
- Code-mixing handled explicitly rather than edited out — Spoken Urdu and spoken Hindi are largely mutually intelligible; the distinction is mainly lexical and orthographic. Decide up front whether transcription is in Nastaliq, Devanagari, or both.
Running a production cohort Urdu build
Nine to twelve weeks, with recruitment running continuously rather than in a front-loaded phase.
Six to eight batches, speaker-disjoint by construction so held-out speakers are genuinely held out.
Fix the script decision before fielding; retro-transcribing a Nastaliq dataset into Devanagari after delivery costs as much as the original transcription pass.
| Parameter | At this volume |
|---|---|
| Cities | Six to eight — Hyderabad, Lucknow, Delhi, Bhopal, Patna |
| Studios | Eight rooms plus two mobile rigs |
| Recruiters | Eight coordinators, one regional manager |
| Audio yield | ~500 hours at 30 minutes per speaker |
| Sessions per day | 45–55 |
| Team | 1 programme lead, 1 regional manager, 8 coordinators, 14 engineers, 25 transcribers, 3 QA leads |
Cohort design
At 1,000 speakers 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.
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.
| Dimension | Typical split | Why it matters for Urdu |
|---|---|---|
| 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 Urdu forms that younger urban speakers have lost |
| Region | Uttar Pradesh / Telangana / Bihar 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 |
Urdu-specific considerations
- Shares most phonology with Hindi but adds Perso-Arabic phonemes (/q/, /x/, /ɣ/, /z/, /f/) that many speakers merge
- Spoken Urdu and spoken Hindi are largely mutually intelligible; the distinction is mainly lexical and orthographic. Decide up front whether transcription is in Nastaliq, Devanagari, or both.
- Indian Urdu specifically, and Dakhini in particular, are absent from public data dominated by Pakistani Urdu broadcast speech.
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
- Right-to-left Nastaliq tooling errors and diacritic loss
- Merged phonemes transcribed by sound rather than by etymology, or vice versa, inconsistently
100% technical QA, 10% content QA stratified by city and coordinator, with voice-based duplicate detection across the whole cohort.
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
Risks at production cohort in Urdu
Cost at this band is driven by: Number of distinct demographic cells rather than total speakers.
- Speaker-disjoint splits are only trustworthy if duplicate detection is voice-based rather than ID-based, since one person can present two identities
- Coordinator-level demographic bias becomes measurable at this size and should be reported, not smoothed over
- Urdu carries 5 recognised varieties across Uttar Pradesh, Telangana, Bihar, so the quota matrix is wider than the headline volume suggests
- Indian Urdu specifically, and Dakhini in particular, are absent from public data dominated by Pakistani Urdu broadcast speech.
Deliverables
- WAV audio to your naming convention, with the per-file manifest
- Verbatim Perso-Arabic (Nastaliq) 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
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 1,000 speakers of Urdu enough?
Enough for production ASR generalisation and for a speaker-verification corpus with meaningful negative pairs.
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 cohort Urdu build take?
Nine to twelve weeks, with recruitment running continuously rather than in a front-loaded phase. Six to eight batches, speaker-disjoint by construction so held-out speakers are genuinely held out.
What does 1,000 speakers of Urdu spontaneous speech cost?
Quoted per delivered hour against this specification. At this band the drivers are number of distinct demographic cells rather than total speakers. 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 and coordinator, with voice-based duplicate detection across the whole cohort.
Quote this Urdu dataset
1,000 speakers, spontaneous speech, Urdu — production cohort. Adjust anything and send it.