Cartesia Sonic-3.6 leads both speech boards

Cartesia’s Sonic-3.6 now ranks first on both Artificial Analysis speech boards—1,283 Elo on Provider Voice and 1,123 on Controlled Voice—while Cartesia states sub-90ms time to first audio. The independent leaderboard comparison matters because the controlled board holds the voice catalog constant; the Sonic API is still beta and hosted-only. Voice-agent builders should file the result as a quality-and-latency signal, not a migration order, until their own round-trip tests beat the archive’s case for treating inference latency as a product decision.