Realtime voice model with plain-English voice direction, one voice identity across 100+ languages, and sub-200ms streaming time-to-first-audio.
InworldAudio GenerationReleased May 5, 2026Proprietary EndpointNewRealtime voice model with plain-English voice direction, one voice identity across 100+ languages, and sub-200ms streaming time-to-first-audio.
Also known as Inworld TTS 2, TTS-2
tts-2/v1/audio/speechPOST/v1/audio/speech:streamGET/v1/voicesinworld-tts-2Live pay-as-you-go rates from the EmpirioLabs catalog. You are billed only for what you use, with no monthly minimum.
TTS 2 serves speech through POST /v1/audio/speech and returns playable audio. Send the text to speak as input with the model id tts-2. Get an API key from the EmpirioLabs dashboard.
curl https://api.empiriolabs.ai/v1/audio/speech \
-H "Authorization: Bearer $EMPIRIOLABS_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "tts-2",
"input": "Welcome to EmpirioLabs. Your build just finished."
}' \
--output speech.mp3import requests
response = requests.post(
"https://api.empiriolabs.ai/v1/audio/speech",
headers={"Authorization": "Bearer YOUR_EMPIRIOLABS_API_KEY"},
json={"model": "tts-2", "input": "Welcome to EmpirioLabs."},
)
with open("speech.mp3", "wb") as f:
f.write(response.content)Request parameters supported by the TTS 2 API on EmpirioLabs. Defaults apply when a field is omitted.
| Parameter | Type | Default | Range / values | Description |
|---|---|---|---|---|
| input | string | - | max 2000 | Text to synthesize. Max 2,000 characters per request; chunk longer copy at sentence boundaries on the client. |
| voice | enum | Sarah | Sarah, Olivia, Elizabeth, Ashley, Wendy, Julia, Priya, Pixie,... | Voice preset. 20 hand-picked voices covering English, Spanish, Portuguese, Hindi, and various accents. For the full voice catalog (including cloned voices), use... |
| voice_id | string | - | - | Free-form voice ID. Overrides voice when set. Use this to address any voice beyond the curated 20-preset list, including cloned and regional voices. Pass any voice... |
| language | enum | en-US | en-US, en-GB, es-ES, es-MX, fr-FR, de-DE, it-IT, pt-BR, pt-PT... | BCP-47 language code. This model holds one voice identity across 100+ languages; pass any supported code here even if it is not in the dropdown. |
| output_format | enum | WAV | MP3, WAV, OGG, FLAC, PCM, ALAW, MULAW | Audio container/codec. WAV = LINEAR16 inside RIFF (ubiquitous). MP3 / OGG = compressed. PCM = headerless raw, useful for chunked real-time playback. FLAC = lossless. |
| sample_rate | enum | 24000 | 8000, 16000, 22050, 24000, 32000, 44100, 48000 | Output sample rate in Hz. 24000 is Inworld's default and what their voice models train at; raise to 48000 for broadcast quality. |
| speed | number | 1 | 0.5 to 1.5 | Speaking rate multiplier. 0.5 = half speed, 1.5 = 50% faster. |
| temperature | number | 1 | 0.1 to 2 | Voice expressiveness / variability. Lower = more consistent / "flat"; higher = more expressive but more variation between renders. |
| bit_rate | number | 128000 | 32000 to 320000 | Bitrate in bps for MP3 / OGG_OPUS. Ignored for other encodings. |
| apply_text_normalization | enum | ON | ON, OFF | When ON, Inworld expands numbers / abbreviations / dates into spoken form ("USD 5" → "five US dollars"). |
| timestamp_type | enum | NONE | NONE, WORD, CHARACTER | If non-NONE, the response includes per-word or per-character timestamps in timestamp_info. Useful for caption / highlight UIs. |
On EmpirioLabs, TTS 2 is billed pay as you go. The live rate card on this page always matches what the API charges.
TTS 2 is served through POST /v1/audio/speech on api.empiriolabs.ai with standard bearer-token authentication.
Yes. The EmpirioLabs playground runs TTS 2 in the browser with the same parameters the API exposes, so you can test prompts before writing code.
Create an EmpirioLabs account, then generate a key under API Keys in the dashboard. Billing is pay-as-you-go credits, so you only pay for the requests you make.
Check out our pricing or reach out if you want your own model deployed on our stack.
