Speko + AssemblyAI
AssemblyAI Universal-3 Pro achieves 5.9% WER across 26 diverse datasets — making it the top pick for noisy, accented, and varied audio conditions. Speko benchmarks it against Deepgram, Whisper, and Google so you can see exactly where it wins.
Last updated: March 2026
What AssemblyAI Does
AssemblyAI is a speech AI platform that combines best-in-class STT with built-in LLM capabilities. Universal-3 Pro is its flagship model — evaluated across more diverse audio conditions than any competing provider.
Universal-3 Pro STT
Universal-3 Pro achieves 5.9% WER averaged across 26 evaluation datasets — covering diverse accents, background noise, telephony audio, and domain-specific vocabulary. The breadth of evaluation makes it the most reliable choice for production audio that isn't studio-clean.
Lemur LLM Integration
AssemblyAI's Lemur lets you run LLM-powered tasks directly on transcripts without routing through a separate model provider. Summarization, sentiment analysis, Q&A, and action item extraction are available as first-party features within the same API.
Best for Diverse and Noisy Audio
While Deepgram Nova-3 leads on clean audio benchmarks, AssemblyAI Universal-3 Pro is trained and evaluated specifically to handle the messy audio that real-world voice agents encounter: accented speakers, background noise, multiple talkers, and low-quality microphones.
How Speko Works with AssemblyAI
Speko integrates with the AssemblyAI API to run standardized accuracy, latency, and cost benchmarks — then places Universal-3 Pro results next to Deepgram, Whisper, and Google for a complete provider comparison.
Universal-3 vs the Field
Run a Speko benchmark to compare AssemblyAI Universal-3 Pro against Deepgram Nova-3, OpenAI Whisper Large v3, and Google Chirp 2. Same audio corpus, same evaluation methodology — see who wins on your actual audio conditions.
Diverse Audio Benchmarks
Speko includes accent-diverse, noise-varied, and telephony-quality test sets alongside studio-clean audio. This matters because clean-audio WER rankings often reverse on real production audio. See where AssemblyAI's advantage over Deepgram appears.
When Universal-3 Pro Is the Top Pick
Speko surfaces provider recommendations based on your audio profile, volume, and cost constraints. When AssemblyAI Universal-3 Pro is the right choice — typically for diverse or challenging audio — Speko's benchmark output makes that case with data.
AssemblyAI Features Benchmarked by Speko
- Universal-3 Pro WER: 5.9% averaged across 26 diverse evaluation datasets
- Streaming transcription with low-latency partial results
- Speaker diarization accuracy on multi-speaker and overlapping speech
- Lemur LLM integration for real-time summarization, sentiment, and action item extraction
- Auto-highlights and chapter detection for long-form audio content
Frequently Asked Questions
Is AssemblyAI better than Deepgram for voice agents?
It depends on your audio conditions. Deepgram Nova-3 leads on clean English audio with 4.1% WER versus AssemblyAI Universal-3 Pro's 5.9% on the same benchmark. However, Universal-3 Pro achieves that 5.9% WER averaged across 26 diverse datasets including noisy, accented, and domain-specific audio — conditions where Nova-3's advantage narrows significantly. If your users speak with diverse accents or call from noisy environments, AssemblyAI may outperform Deepgram in production even though it trails on clean-audio benchmarks.
How does AssemblyAI Universal-3 compare to Deepgram Nova-3?
Universal-3 Pro and Nova-3 are the two leading STT models in 2026. Nova-3 wins on clean English audio (4.1% vs 5.9% WER). Universal-3 Pro wins on diverse and challenging audio — it's evaluated across 26 datasets spanning different accents, noise levels, and domains, where its broader training data gives it an edge. Universal-3 also includes built-in Lemur LLM integration for post-processing tasks like summarization and sentiment analysis that are separate steps with Deepgram.
When should I use AssemblyAI instead of Deepgram?
Choose AssemblyAI Universal-3 Pro when: (1) your audio input is diverse — multiple accents, background noise, telephony quality; (2) you need built-in LLM post-processing like summaries, action items, or sentiment analysis via Lemur; (3) accuracy on challenging audio matters more than squeezing out the last millisecond of streaming latency. Choose Deepgram Nova-3 when you're processing clean studio or VoIP audio and streaming latency is your primary optimization target.
How much does AssemblyAI cost per hour of audio?
AssemblyAI Universal-3 pricing starts at competitive rates for pay-as-you-go usage, with volume discounts available. The exact per-minute rate is comparable to Deepgram Nova-3 in the same tier. Value-added features like Lemur (LLM integration), speaker diarization, and sentiment analysis are priced as add-ons. Speko tracks current pricing across all major STT providers and surfaces total cost-per-hour including the features you actually use.
See How AssemblyAI Performs Against the Competition
Clean-audio benchmarks don't tell the full story. Run a Speko test across diverse audio conditions to see whether AssemblyAI Universal-3 Pro is the right STT provider for your real-world voice agent workload.