Listeners rate Cartesia's Sonic 3.6 above every Amazon Polly engine.
ServiceNow, Decagon, and Quora run their production voice agents on Cartesia. One model, 44 languages, first audio in under 90ms.
Voice quality
Listeners rate Sonic 3.6 above every Polly engine
- Artificial Analysis plays listeners two clips of the same line without naming the model, and rates every model on the board the same way.
- Sonic 3.6 leads Polly Generative, Polly's highest-rated engine, by more than 200 points.
Provider Voice Arena Elo
Higher is better
Speed
Sonic 3.6 generates faster than Polly's two highest-rated engines
- Artificial Analysis times every model on the board with the same harness, in characters generated per second.
- Sonic 3.6 outpaces Polly Generative and Polly Long-form, so the voice listeners prefer is also the quicker one.
Characters per second
Higher is better
Reasons why companies choose Cartesia over Amazon Polly
Generative, Long-form, Neural, StandardHuman-like naturalness
Intonation, pacing, pronunciation, emotion, and audio quality that drive higher completion rates
Cartesia1291 EloAmazon Polly1065 EloPolly Generative1030 EloPolly Long-form896 EloPolly Neural830 EloPolly StandardOctober 2026
Languages
Comprehension and trust across a global customer base.
Cartesia44 languages from one model, with native accentsAmazon PollyGenerative voices in 9 languagesCustom voices
How much audio it takes, and who is allowed to use one.
CartesiaInstant clone from 10 seconds, professional clone from 30 minutes, on the public APIAmazon PollyBrand Voice, a custom engagement with the Amazon Polly teamDeployment
Decides whether regulated teams can use it at all.
CartesiaOn-prem and air-gapped, already running at government, healthcare, and financial institutions, behind a 99.9% uptime SLAAmazon PollyGenerative voices in 10 AWS regionsEnd-to-end stack
How many products it takes to run one call.
CartesiaTTS, STT, and Agents from one vendor, on one APIAmazon PollyPolly for speech, with transcription and agents in separate AWS services
Frequently asked questions
Is AWS Polly the same as Amazon Polly?
Yes. Amazon Polly is the text to speech service in AWS, and it is searched under both names. This page compares Sonic 3.6 with all four Polly engines: Generative, Long-form, Neural, and Standard.
How is the quality score measured?
It comes from Artificial Analysis, an independent benchmark. Listeners hear two clips of the same line without being told which model produced either, and pick the one they prefer. Sonic 3.6 rates above all four Polly engines: Generative, Long-form, Neural, and Standard.
How many languages does Cartesia support?
44 languages from one model, including English, Spanish, French, German, and Japanese. Accents are calibrated per region rather than bolted onto an English model. Polly's generative voices cover 9 languages.
Can I use my own voice with Cartesia?
Yes. An instant clone takes 10 seconds of audio and a professional clone takes 30 minutes. Both are self-serve on the public API. Amazon Polly's custom voice, Brand Voice, is built with the Polly team as a custom engagement.
Can I run Cartesia on my own infrastructure?
Yes. Cartesia deploys on-prem and air-gapped, which teams in healthcare, finance, and government use to keep audio inside their own network, backed by a 99.9% uptime SLA.
How long does it take to switch from Amazon Polly?
One to two weeks for most teams. Cartesia is integrated into the major voice agent platforms and every model is on the public API, so there is no platform to move onto and nothing to unpick later.
More comparisons
Get started today
Talk to an expert.
Connect with a member of our team and learn how Cartesia can help you build world-class voice experiences.
Start building.
Access our models via API and bring a voice agent into production in minutes.