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Dataset specification · Evaluation scale

100 hours of Bengali Conversational Speech

An evaluation scale build of 100 hours of Bengali conversational speech. Building a benchmark or evaluation set that is large enough to trust, or fine-tuning a narrow domain. 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 — 100 hours of Bengali Conversational Speech
Volume
100 hours
Scale
Evaluation scale
Per speaker
20–30 minutes of accepted audio per speaker, in pairs
Accepted yield
55–65% of recorded time is accepted
01

How Bengali 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 scale — what the build is actually made ofCitiesTwo, chosen for dialect…StudiosTwo rooms running in pa…RecruitersTwo coordinatorsSpeakers~200–240Sessions per day12–16 across both citiesTeam2 coordinators, 4 engin…
02

The specification

FieldValue
LanguageBengali (bn-IN, Bengali)
Volume100 hours
Equivalent200 speakers at 30 minutes each, or 100 speakers at one hour each
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
DialectsKolkata standard (Rarhi), Sylheti-influenced, Rangpuri / North Bengal, Medinipuri
TranscriptionVerbatim, native-speaker, second-pass reviewed
Diverse Indian speakers waiting for multilingual data collection sessions — supporting 100 hours of bengali conversational speech
Diverse Indian speakers waiting for multilingual data collection sessions
03

Designing the scenarios for Bengali

  • 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 Bengali specifically: Inherent vowel is realised as /ɔ/ or /o/, which breaks G2P rules copied from Devanagari-based systems
  • Code-mixing handled explicitly rather than edited out — Kolkata professional speech mixes English heavily; rural West Bengal much less. A single 'Bengali' dataset without register tags conflates two very different acoustic and lexical distributions.
04

Running an evaluation scale Bengali build

Four to six weeks. Two cities running in parallel means recruitment and recording overlap rather than queue behind each other.

Three batches at roughly two-week intervals, each one a self-contained, speaker-disjoint slice you can evaluate independently.

Tag every speaker as Indian Bengali and record district of origin; mixing in Bangladeshi speech without tags is a common and costly dataset defect.

ParameterAt this volume
CitiesTwo, chosen for dialect contrast — Kolkata, Siliguri
StudiosTwo rooms running in parallel
RecruitersTwo coordinators
Speakers~200–240
Sessions per day12–16 across both cities
Team2 coordinators, 4 engineers, 6 transcribers, 1 QA lead
05

Cohort design

At 100 hours the cohort is deliberately simplified: two or three dialect groups rather than the full spread, with quotas enforced in aggregate. A build this size cannot support per-cell targets and should not claim to.

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 Bengali
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 Bengali forms that younger urban speakers have lost
RegionWest Bengal / Tripura / Assam (Barak Valley) 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

Bengali-specific considerations

  • Inherent vowel is realised as /ɔ/ or /o/, which breaks G2P rules copied from Devanagari-based systems
  • Kolkata professional speech mixes English heavily; rural West Bengal much less. A single 'Bengali' dataset without register tags conflates two very different acoustic and lexical distributions.
  • Indian Bengali is under-collected relative to Bangladeshi Bengali, and North Bengal and Tripura varieties are almost entirely 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
  • Three sibilant characters chosen inconsistently for the same sound
  • Bangladeshi vs Indian Bengali orthographic conventions mixed within one dataset

100% technical QA, 25% content QA, escalating to full review on any batch that fails the agreed error threshold.

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 scale in Bengali

Cost at this band is driven by: Dialect spread is the main driver at this band — two contrasting cities cost more than two convenient ones; Turnaround compression, if you need it inside four weeks.

  • Two-city cohorts can hide a dialect gap that only appears when the model meets a third region
  • Transcription consistency between two city teams needs an explicit convention document or the batches will not match
  • Bengali carries 5 recognised varieties across West Bengal, Tripura, Assam (Barak Valley), so the quota matrix is wider than the headline volume suggests
  • Indian Bengali is under-collected relative to Bangladeshi Bengali, and North Bengal and Tripura varieties are almost entirely missing.
10

Deliverables

  • WAV audio to your naming convention, with the per-file manifest
  • Verbatim Bengali 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 100 hours of Bengali enough?

A solid evaluation set, and enough to fine-tune an existing multilingual model on a narrow domain. Still short of what a general production model needs.

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 scale Bengali build take?

Four to six weeks. Two cities running in parallel means recruitment and recording overlap rather than queue behind each other. Three batches at roughly two-week intervals, each one a self-contained, speaker-disjoint slice you can evaluate independently.

What does 100 hours of Bengali conversational speech cost?

Quoted per delivered hour against this specification. At this band the drivers are dialect spread is the main driver at this band — two contrasting cities cost more than two convenient ones and turnaround compression, if you need it inside four weeks. Send the spec and you get one fixed figure.

How much QA is applied at this volume?

100% technical QA, 25% content QA, escalating to full review on any batch that fails the agreed error threshold.

Quote this Bengali dataset

100 hours, conversational speech, Bengali — evaluation scale. Adjust anything and send it.

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