Humanness Index™ · Provider

Cartesia

Cartesia was founded by the researchers who created state space models, the S4 and Mamba architectures from their academic work.

Best ranked model: #12 Sonic 3.6
Humanness: 71

Standings as of Oct 26, 2026, 16:41 UTC

Models on the Index: 5
Languages: 42
Price / 1M chars: $50

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Cartesia models on the Humanness Index™

Rank	Model	Humanness	Latency	Languages	Price / 1M chars
#22	Sonic	0	116 ms	15	$50
#17	Sonic 2	67	159 ms	15	$50
#18	Sonic 3	67	166 ms	42	$50
#14	Sonic 3.5	71	128 ms	42	$50
#12	Sonic 3.6	71	101 ms	44	$50

Compare against the full Humanness Index™ rankings

About Cartesia

Cartesia was founded by the researchers who created state space models, the S4 and Mamba architectures from their academic work. Every Sonic generation is a state space model rather than a Transformer, which is the architectural basis of the latency claims the family is known for.

Sources: cartesia.ai

Platform and compliance

Five Sonic generations sit on the Humanness Index™, from the May 2024 debut model to Sonic 3.6. Since Sonic 3 the platform has carried SOC 2 Type II, HIPAA, and PCI Level 1 compliance, aimed at regulated phone work.

Sources: docs.cartesia.ai

Cartesia stats

Languages: 42¹
Price / 1M chars: $50²

docs.cartesia.ai (checked 2026-06-10) Sonic 3 and 3.5; earlier Sonic and Sonic 2 shipped 15, encoded per model.
cartesia.ai/pricing (checked 2026-10-26) The displayed $50 per 1M characters is the effective rate of Pro included credits ($5/month for 100K), assuming full use, rather than an overage rate. Startup included credits are about $39.20/1M ($49 for 1.25M); Scale about $37.38/1M ($299 for 8M). Overages cost $65/$45/$38 per 1M credits on Pro/Startup/Scale. TTS uses approximately 1 credit per character; preprocessing can affect usage (docs.cartesia.ai/pricing). Professional voice clones require Startup or higher; custom Enterprise rates may differ.