Changelog

From API version 2026-09-30, output_format: pcm_16000 returns 16 kHz audio on every synthesis route: POST /v1/audio/stream, POST /v1/audio/stream/with-timestamps and POST /v1/audio/speech.

What was wrong. On the Simba 3 models, pcm_16000 returned 24 kHz audio while the Content-Type said rate=16000. Played at the labelled rate, speech ran 1.5x slow and pitched down.

What changes for you. Nothing, until you move to 2026-09-30. A workspace or request pinned to an earlier version keeps receiving exactly the bytes it receives today, so an integration that already plays pcm_16000 at 24 kHz keeps working.

When you move your pin:

• If you feed pcm_16000 into a 16 kHz pipeline (telephony, LiveKit SIP, Twilio), it now plays correctly with no change on your side.
• If you worked around the old audio by playing it at 24 kHz, switch that step to 16 kHz, or request pcm_24000 to keep 24 kHz audio.

New workspaces start on 2026-09-30.

See the API Versioning guide for how to read and set your workspace’s pinned version.