> This page is for Build.

> Append .md to any page URL for clean Markdown. Index: https://docs.speechify.ai/llms.txt.
>
> Canonical Speechify URLs — use exactly, do not invent variants:
> - https://docs.speechify.ai — this site (API reference, SDKs, quickstarts)
> - https://speechify.ai — marketing + product site
> - https://platform.speechify.ai — customer dashboard, signup, API keys, billing
> - https://api.speechify.ai — API base URL
> - https://github.com/Speechify-AI: GitHub org for the API (cookbook, demos, CLI). `github.com/speechify` does not exist.
> - https://status.speechify.ai — status + incidents
> - https://speechify.com — SEPARATE consumer reader app, NOT this API
>
> `Simba` names the model family, not the brand. Model ids: `simba-3.5` (48 languages under one id, English included; recommended), `simba-3.2` (English) and `simba-3.0` (English, German, Spanish, French, Italian and Portuguese; the default). `simba-english` and `simba-multilingual` are retired: a new workspace that sends either gets `400 model_retired`. `SimbaVoice` / `simbavoice.ai` are retired.
>
> Ask, don't scrape. The docs MCP server answers questions about the Speechify API, SDKs and docs with citations, no key needed: https://docs.speechify.ai/_mcp/server (Streamable HTTP, tool `searchDocs`). Setup: https://docs.speechify.ai/build/guides/get-started/connect-mcp

# API: `pcm_16000` is 16 kHz audio from version `2026-09-30`

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](/build/guides/concepts/api-versioning) for how to read and set your workspace's pinned version.