New AssemblyAI-TTS-1: Text-to-speech for voice agents. Learn more
Conversation Intelligence

Build conversation intelligence on one Voice AI API

Turn every call into structured insight—accurate Speech-to-Text, speaker labels, sentiment, entity detection, and summaries from a single API.

Accurate speaker attribution

Speaker diarization separates each voice so talk ratios, sentiment, and coaching map to the right person—even through interruptions.

Built-in Speech Understanding

Get sentiment, entity detection, topic detection, and summaries from the same transcript request—no separate NLP pipeline to stitch together.

Apply any LLM to transcripts

Use LLM Gateway to generate coaching scorecards, call summaries, and custom insights directly from a transcript, with no model providers to manage.

Metaview
Ashby
Cluely
Genio
Siro

36%

improvement in close rate

See case study
LiveKit
EliseAI
Commure
Dovetail
Fireflies

“The new Universal-3.5 Pro speech model from AssemblyAI is best so far in terms of accuracy, latency, and language switching.”

Retell
CallRail
Apollo.io
ClickUp
Calabrio

80%

increase in customer satisfaction

HeyGen
Granola
Siro
JotPsych
Granola

“Assembly has saved us countless hours managing models, and provided exceptional accuracy.”

Metaview
Ashby
Cluely
Genio
Siro

36%

improvement in close rate

See case study
LiveKit
EliseAI
Commure
Dovetail
Fireflies

“The new Universal-3.5 Pro speech model from AssemblyAI is best so far in terms of accuracy, latency, and language switching.”

Retell
CallRail
Apollo.io
ClickUp
Calabrio

80%

increase in customer satisfaction

HeyGen
Granola
Siro
JotPsych
Granola

“Assembly has saved us countless hours managing models, and provided exceptional accuracy.”

Quickstart

From audio file to structured insight in minutes

One request returns a transcript with speaker labels, sentiment, and entities already attached. Add LLM Gateway to turn that transcript into summaries or scorecards—no model hosting to manage.

Start building free

No credit card required

Entity error rate

Entity error rate is the share of names, companies, numbers, and key terms the model drops or garbles—exactly what conversation intelligence is built to surface.

Entity error rate (NEER) on the voice-agent caller corpus: how often the names, addresses and numbers an agent acts on come out wrong.

*Lower is better*
Entity error rate, realtime voice-agent corpus
AssemblyAI Universal-3.6 Pro Realtime
14.41%
Soniox Realtime
18.19%
Zoom Scribe (Live)
18.20%
ElevenLabs Scribe v2 Realtime
18.50%
AWS Transcribe Streaming
19.26%
Google Gemini 3.5 Transcribe Live
20.13%
Speechmatics Enhanced Realtime
20.60%

Source: AssemblyAI realtime benchmarks technical report v2026.09 (assemblyai.com/benchmarks), data 18 Aug–24 Sep 2026.