New Universal-3.5 Pro is here. Learn more: Async Realtime
Speech Analytics

Analyze every call with one speech analytics API

Transcribe 100% of your calls with high accuracy, then add speaker labels, sentiment, entity detection, and PII redaction for QA and compliance—all from one API built for telephony audio at scale.

Accurate on telephony audio

Universal-3 Pro is tuned for 8kHz call audio, with multichannel support so agent and customer are cleanly separated.

PII redaction for compliance

Redact names, card numbers, and account data in both text and audio to support PCI and GDPR workflows across your call archive.

QA-ready insights

Per-utterance sentiment, entity detection, and summaries turn raw recordings into QA scores, escalation flags, and coaching signals.

Metaview
Ashby
Cluely
Genio
Siro

36%

improvement in close rate

See case study
LiveKit
Earmark
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
Earmark
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

Score calls at scale without a custom pipeline

Submit recordings in batch and get back transcripts with speaker separation, redacted PII, sentiment, and entities in a single response. Use webhooks for high-volume workloads so your QA system processes thousands of calls without polling.

Start building free

No credit card required

Word error rate

Speech analytics is only as trustworthy as the transcript under it. Word error rate measures accuracy against a human reference on pre-recorded audio—the QA workload most analytics runs on.

Pre-recorded word error rate on English audio.

*Lower is better*
AssemblyAI Universal-3 Pro
4.50%
OpenAI GPT-4o Transcribe
5.34%
Deepgram Nova-3
6.66%
Azure Batch
7.02%

Source: AssemblyAI published benchmarks — assemblyai.com/benchmarks.