Data Annotation Services · Audio Annotation
Audio Annotation and Transcription Services
Verbatim and clean-verbatim transcripts, speaker diarization, word-level timestamps and audio event tagging for ASR, voice assistants and speech analytics, in many languages and dialects.
- ASR-grade transcription
- Multi-language & dialects
- SRT, TextGrid, RTTM, JSON
Audio Annotation Services
Speech Data Built for Training, Not Just Reading
A transcript written for a person to read is not the same as one written to train a speech model. ASR data needs consistent rules for fillers, false starts, numbers, acronyms, code-switching and the words nobody can quite make out, plus timestamps that line up with the waveform. Zilo AI's audio annotation and transcription services follow your style guide to the letter, and every batch is checked against the audio before export.
We work on call-centre recordings, meetings and interviews, voice commands, podcasts and media, field recordings and read speech, across Indian and global languages and their dialects. Run it as a managed project, or add dedicated transcriptionists and audio annotators who work in your own tool.
ASR Transcription
Verbatim or clean-verbatim transcripts with your rules for fillers, numbers, acronyms and unclear speech.
Speaker Diarization
Who spoke when, with overlap marking and segment boundaries aligned tightly to the waveform.
Audio Event Tagging
Noise, music, silence and non-speech sounds tagged, along with emotion, intent and speaker attributes.
Languages and Dialects
Native-speaker transcription and review across major Indian and global languages, including code-mixed speech.
What We Annotate
Audio Annotation Tasks We Deliver
From raw transcription to diarization, event tagging and evaluation of ASR and TTS output, each task follows your style guide and is reviewed against the audio before delivery.
Voice / Audio Data Annotator
Listens to audio clips and labels speech and non-speech content: segmenting utterances, marking noise, music and silence, and tagging speaker attributes, language, intent or sentiment according to your taxonomy.
ASR Transcriptionist
Produces verbatim or clean-verbatim transcripts for ASR training and evaluation, applying your rules for fillers, false starts, numbers, acronyms, code-switching and unclear speech, with utterance- or word-level timestamps.
Speaker Diarization & Timestamping
Marks who spoke when in multi-speaker audio such as meetings, interviews and support calls, handles overlapping speech and short interjections, and aligns segment boundaries tightly to the waveform.
Audio Event & Emotion Tagging
Labels sound events such as alarms, sirens, laughter, applause and background noise, and rates emotion, sentiment and speaking style for voice analytics, sound recognition and expressive speech models.
Multilingual & Dialect Transcription
Language experts transcribe speech across 22 languages, capturing regional accents, dialect vocabulary and code-mixed speech, and deliver native-script or romanized output with optional translation, as your project requires.
ASR & TTS Output Evaluation
Checks machine transcripts against the audio to correct errors and support word error rate analysis, and rates synthetic voices for naturalness, pronunciation and prosody in structured listening tests.
For ML & Data Teams
How to Brief an Audio Annotation Vendor
Speech data goes wrong in small, repeated ways: a number written as digits in one file and words in the next, a laugh tagged by one transcriptionist and ignored by another. A clear style guide prevents most of it. Use this checklist before you send audio to any vendor, Zilo AI included.
Questions to ask any annotation vendor
- Do your transcriptionists speak the language and dialect natively, and how is that checked?
- How do you handle code-switching, for example Hindi and English in the same sentence?
- What do you mark when speech is unclear, overlapping or partly in another language?
- How do you check timestamp alignment, and to what precision?
- Is every file reviewed against the audio, or only a sample?
- Which export formats can you deliver: SRT, WebVTT, TextGrid, RTTM, JSON?
Write the Style Guide First
Decide verbatim or clean verbatim, and how to write numbers, dates, currencies, acronyms, brand names and spelled-out letters.
Decide on Fillers and Disfluencies
Say whether um, ah, repetitions and false starts are kept, removed or tagged. ASR training and analytics usually need different answers.
Plan for Code-Switching
Agree the script for each language in mixed speech, for example English words in Latin script inside a Hindi sentence.
Set the Timestamp Level
Utterance, segment or word-level timestamps cost very different amounts of time. Ask only for the level your model uses.
List the Non-Speech Tags
Give a fixed list of tags for noise, music, laughter, silence and crosstalk, so every file uses the same set.
Pilot on Difficult Audio
Include noisy calls, strong accents and overlapping speakers in the pilot. Clean studio audio will not test the guideline.
Engagement Models
Flexible Ways to Work With Us
Outsource a complete annotation project or extend your in-house data team, whichever suits your pipeline.
Managed Projects
Share your data and guidelines, and we handle annotation, quality checks and delivery of AI-ready datasets on schedule.
Best forEnd-to-end outsourcing
Pilot Batch
Start with a small, calibrated sample to validate guidelines, accuracy and turnaround before committing to scale.
Best forNew projects & vendor evaluation
Dedicated Teams
Trained annotators work exclusively on your project, in your tools and workflows, with a single point of contact.
Best forOngoing, high-volume pipelines
Annotator Staffing
Hire trained annotators, raters and linguists on contract to extend your in-house data or AI team.
Best forScaling your own team
How It Works
From Raw Data to AI-Ready Data
A structured workflow built around your guidelines, with quality checks at every stage.
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1
Share
Send us sample data, your label taxonomy or guidelines, target volumes and preferred output format.
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2
Pilot
We annotate a calibration batch, align on edge cases and refine guidelines together with your team.
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3
Scale
Trained annotators work through your data at volume, with multi-level review and QA sampling.
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4
Deliver
Receive accurate, consistently labeled data in your format, and iterate as your models evolve.
Why Zilo AI
Why AI Teams Choose Zilo AI for Data Annotation
Good training data comes from a repeatable process, not a one-off delivery. We pair trained people with agreed guidelines and layered quality checks, and adapt to your tools, formats and engagement model instead of forcing ours.
- One partner for image, video, text, audio and LLM data
- Pilot batches and guideline calibration before scaling
- Multi-level review with gold-standard and consensus checks
- Delivery in COCO, YOLO, JSONL, SRT or your custom schema
- Secure, access-controlled workflows aligned to your data policies
- Managed projects or dedicated annotators on contract
Industries We Serve
- Autonomous Vehicles & Mobility
- AI Labs & LLM Developers
- E-commerce & Retail
- Healthcare & Life Sciences
- BFSI & Fintech
- Search & Discovery
- Manufacturing
- Media & Entertainment
- Agriculture
Multilingual Coverage
Our Global Language Expertise
Our trained annotators and language experts work across major global and regional languages, so your AI performs for a worldwide audience.
- German
- French
- Portuguese
- Spanish
- Italian
- Russian
- Polish
- Swedish
- Turkish
- Arabic
- Chinese
- Mandarin
- Malay
- Korean
- Dutch
- Greek
- Romanian
- Slovak
- Danish
- Croatian
- Czech
- Vietnamese
FAQs
Audio Annotation and Transcription: Common Questions
Have a question we have not answered? Talk to our team and we will get back to you quickly.
Talk to Our Team
- +91 77604 02792
- connect@ziloservices.com
- Mon to Fri: 8am to 10pm
- Hebbal Kempapura, Bangalore
What audio annotation services does Zilo AI offer?
We provide verbatim and clean-verbatim ASR transcription, speaker diarization and timestamping, audio segmentation, audio event and emotion tagging, language identification, multilingual and dialect transcription, and evaluation of ASR and TTS output.
Is this the same as a general transcription service?
Our focus is transcription and labelling for AI: speech recognition, voice assistants and speech analytics. That means strict style-guide rules, timestamps aligned to the audio and machine-readable exports, rather than a document for people to read.
Which languages do you transcribe?
Our language experts cover major Indian and global languages, including code-mixed speech. Tell us your languages and dialects and we will confirm coverage before the pilot.
What formats do you deliver?
We deliver JSON or JSONL, SRT, WebVTT, Praat TextGrid and RTTM, or a custom schema that matches your pipeline.
How do you check transcription quality?
Every batch is reviewed against the audio before export. Projects start with a pilot to align on the style guide, then run with multi-level review and gold-standard checks.
Can we hire dedicated transcriptionists instead of outsourcing a project?
Yes. We can provide dedicated transcriptionists and audio annotators on contract who work inside your tools and processes.
Ready to Start Your Audio Annotation Project?
Share sample recordings, your languages and your style guide, and we will transcribe a pilot batch so you can check it against the audio yourself.