Jul 18, 2026 · 6 min read
Audio Annotation Services: How to Choose the Right Vendor
A practical buyer's guide to audio annotation services. What annotation types cost, how to judge quality, the questions to ask vendors, and when to build in-house.
Blog
Speech data, explained properly
What we’ve learned collecting, transcribing, and licensing tens of thousands of hours of speech, written for the teams training the models.
Jul 17, 2026 · 6 min read
The Data Behind Voice Cloning: Recordings, Consent, and Quality
What voice cloning actually needs from its training data: how many minutes, what recording quality, and why consent and licensing decide whether you can ship it.
Jul 16, 2026 · 7 min read
Wake Word Detection: How It Works and How to Train a Custom Wake Word
Wake word detection explained: how always-on keyword spotting works, false accepts vs false rejects, tools like Porcupine and openWakeWord, and training data.
Jul 16, 2026 · 5 min read
Synthetic Speech Data vs Real Recordings: What Trains Better Models
When synthetic speech data helps, when it hurts, and how to combine it with real recordings. A practical comparison for teams training ASR and voice AI.
Jul 16, 2026 · 6 min read
Speech Data Collection: The Complete 2026 Guide
Speech data collection from spec to delivery: recruitment, consent and GDPR, recording setups, QA, transcription, costs, and the build-vs-buy decision.
Jul 16, 2026 · 7 min read
How to Fine-Tune Whisper: A Practical Guide (2026)
How to fine-tune Whisper with Hugging Face Transformers: dataset format, code, LoRA, data volumes per goal, WER evaluation, and the pitfalls to avoid.
Jul 15, 2026 · 5 min read
Speech Data for Voice Agents and Call-Center AI
What training data voice agents and call-center AI actually need: real conversational audio, domain vocabulary, noisy conditions, and the metadata that makes it usable.
Jul 14, 2026 · 5 min read
Voice Data Privacy: Consent, PII, and GDPR for Speech Datasets
How to handle consent, personal data, and PII redaction in speech datasets. A practical compliance primer for teams collecting or buying voice data.
Jul 13, 2026 · 5 min read
Accent and Dialect Diversity in Speech Data
Why accent and dialect coverage decides whether your speech model works for real users, how to measure the gaps, and how to build a representative dataset.
Jul 9, 2026 · 6 min read
Word Error Rate (WER) Explained: How to Measure Speech Recognition Accuracy
Word error rate (WER) explained: the (S+D+I)/N formula with a worked example, computing WER with jiwer, normalization pitfalls, CER, and typical WER bands.
Jul 9, 2026 · 7 min read
The Best ASR Models in 2026: Open-Source and Commercial Compared
The best ASR models in 2026 compared: Whisper, NVIDIA Canary and Parakeet, Deepgram, AssemblyAI. Accuracy, languages, licenses, and how to choose.
Jul 2, 2026 · 7 min read
Speaker Diarization: How 'Who Spoke When' Actually Works
Speaker diarization explained: the VAD → embedding → clustering pipeline, end-to-end models, tools like pyannote and WhisperX, and the DER metric.
Jul 2, 2026 · 6 min read
15 Best Open-Source Speech Datasets for ASR and TTS (2026)
The 15 best open-source speech datasets for ASR and TTS in 2026: sizes, languages, licenses, and honest notes on where open data falls short.
Jul 1, 2026 · 6 min read
Code-Switching: What It Is and Why It Breaks Speech Recognition
What is code switching? Definition, linguistic types, real examples like Hinglish and Spanglish, and why it remains ASR's hardest everyday problem.
Jun 26, 2026 · 7 min read
What Is Voice Activity Detection (VAD)? How It Works and Why It Matters
Voice activity detection (VAD) explained: how energy-based and ML-based VAD works, where it sits in ASR and voice-agent pipelines, and how to evaluate it.
Jun 24, 2026 · 7 min read
What Is Speech Synthesis? From Formant Synthesis to Neural TTS
What is speech synthesis? How TTS evolved from formant and concatenative systems to neural models like VITS, and why training data now decides quality.
Jun 18, 2026 · 6 min read
What Is Audio Annotation? Types, Process, and Best Practices
Audio annotation explained: transcription, diarization, timestamps, and acoustic events, plus QA methods, cost drivers, and build-vs-buy tradeoffs.
Jun 18, 2026 · 6 min read
Conversational vs. Scripted Speech Data: Which Does Your Model Need?
Conversational speech datasets vs. scripted read speech: acoustic differences, the WER gap on spontaneous speech, and which to use for ASR, TTS, and voice AI.
Jun 4, 2026 · 6 min read
What Is Automatic Speech Recognition (ASR)? A Practical Guide
What is automatic speech recognition? A practical ASR definition, how modern speech recognition works, WER explained, and the training data behind it.
Jun 4, 2026 · 6 min read
How Much Audio Data Do You Need to Train an ASR Model?
How much data to train speech recognition: 5-50 hrs to fine-tune Whisper, 50-500 hrs for accents, 1,000+ hrs for a new language. Bands, caveats, tables.
May 20, 2026 · 6 min read
TTS Datasets: How to Choose Training Data for Text-to-Speech Models
What makes a good TTS dataset: audio quality, hours per voice, phonetic coverage, prosody, and licensing, from VITS fine-tuning to zero-shot voice cloning.
May 6, 2026 · 6 min read
How to Buy AI Training Data: A Practical Playbook (2026)
How to buy AI training data without getting burned: provider types, pricing models, consent and license checks, red flags, and a procurement checklist.