TTS 2 Flash vs TTS 2

TTS 2 Flash and TTS 2 side by side: specs, capabilities, parameters, and live pricing from the EmpirioLabs catalog.

Inworld Audio Generation

TTS 2 Flash vs TTS 2 at a glance

TTS 2 Flash and TTS 2 are both Inworld models in the Audio Generation category, available through the EmpirioLabs API.

Key differences

  • TTS 2 Flash is the newer release (Sep 2, 2026); TTS 2 was released on May 5, 2026.
  • Capabilities listed only for TTS 2: expressive prosody, voice direction.
  • TTS 2 Flash lists the lower rate for Synthesis (per 1M characters).

TTS 2 Flash vs TTS 2: specs

SpecTTS 2 FlashTTS 2
Model IDtts-2-flashtts-2
AuthorInworldInworld
ReleasedSep 2, 2026May 5, 2026
Input
Text
Text
Output
Audio
Audio
Endpoints
POST /v1/audio/speech POST /v1/audio/speech:stream GET /v1/voices
POST /v1/audio/speech POST /v1/audio/speech:stream GET /v1/voices
Capabilities
multi speaker real time low latency streaming word timestamps character timestamps multilingual
multi speaker real time low latency streaming word timestamps character timestamps multilingual expressive prosody voice direction

TTS 2 Flash vs TTS 2: API pricing

Live rates from the EmpirioLabs catalog for both models. Each rate card always matches what the API charges.

TTS 2 Flash vs TTS 2: API parameters

Request parameters each model lists on EmpirioLabs, with the allowed values or range where one applies. A dash marks a parameter the model does not list.

ParameterTTS 2 FlashTTS 2
inputmax 2000max 2000
voiceSarah, Olivia, Elizabeth, Ashley, Wendy, Julia, Priya, Pixie,... Default: SarahSarah, Olivia, Elizabeth, Ashley, Wendy, Julia, Priya, Pixie,... Default: Sarah
voice_idstringstring
languageen-US, en-GB, es-ES, es-MX, fr-FR, de-DE, it-IT, pt-BR, pt-PT... Default: en-USen-US, en-GB, es-ES, es-MX, fr-FR, de-DE, it-IT, pt-BR, pt-PT... Default: en-US
output_formatMP3, WAV, OGG, FLAC, PCM, ALAW, MULAW Default: WAVMP3, WAV, OGG, FLAC, PCM, ALAW, MULAW Default: WAV
sample_rate8000, 16000, 22050, 24000, 32000, 44100, 48000 Default: 240008000, 16000, 22050, 24000, 32000, 44100, 48000 Default: 24000
speed0.5 to 1.5 Default: 10.5 to 1.5 Default: 1
temperature0.1 to 2 Default: 10.1 to 2 Default: 1
bit_rate32000 to 320000 Default: 12800032000 to 320000 Default: 128000
apply_text_normalizationON, OFF Default: ONON, OFF Default: ON
timestamp_typeNONE, WORD, CHARACTER Default: NONENONE, WORD, CHARACTER Default: NONE

TTS 2 Flash vs TTS 2: limits and notes

TTS 2 Flash

Limits

  • Max input: 2,000 characters per request (chunk longer text at sentence boundaries)
  • WebSocket: 20 concurrent connections, 5 contexts/connection
  • Per-WS message: 1,000 characters

Voice direction

  • This model does not apply bracketed plain-English delivery direction. Use TTS 2 when you need it, or shape delivery here with the speed and temperature controls.

Latency

  • p90 TTFB: under 25 ms (Inworld benchmark)

Voices

  • One voice identity held across 200+ languages and locales, including switching language mid-generation
  • Curated presets in the dropdown; pass any other voice ID via voice_id

TTS 2

Limits

  • Max input: 2,000 characters per request (chunk longer text at sentence boundaries)
  • WebSocket: 20 concurrent connections, 5 contexts/connection
  • Per-WS message: 1,000 characters

Voice direction

  • Open the text with a bracketed instruction in plain English to steer delivery, for example [whispering], [excited], or [Speak warmly, like you are greeting an old friend]
  • The bracketed text is treated as direction and is not read aloud
  • Direction text counts toward the billed character total, so keep it short

Latency

  • p90 TTFB: under 100 ms (Inworld benchmark)

Voices

  • One voice identity held across 200+ languages and locales, including switching language mid-generation
  • Curated presets in the dropdown; pass any other voice ID via voice_id

How to call TTS 2 Flash and TTS 2

TTS 2 Flash serves speech through POST /v1/audio/speech and returns playable audio. Send the text to speak as input with the model id tts-2-flash. Both models are called through the same endpoint. Set model to tts-2-flash or tts-2. Get an API key from the EmpirioLabs dashboard.

cURL
curl https://api.empiriolabs.ai/v1/audio/speech \
  -H "Authorization: Bearer $EMPIRIOLABS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "tts-2-flash",
    "input": "Welcome to EmpirioLabs. Your build just finished."
  }' \
  --output speech.mp3

TTS 2 Flash vs TTS 2: common questions

What is the difference between TTS 2 Flash and TTS 2?

TTS 2 Flash is the newer release (Sep 2, 2026); TTS 2 was released on May 5, 2026. Capabilities listed only for TTS 2: expressive prosody, voice direction. TTS 2 Flash lists the lower rate for Synthesis (per 1M characters). The specs, rate cards, and parameters on this page come from the live EmpirioLabs catalog.

Which is newer, TTS 2 Flash or TTS 2?

TTS 2 Flash is the newer release (Sep 2, 2026); TTS 2 was released on May 5, 2026.

Which has the lower rate, TTS 2 Flash or TTS 2?

TTS 2 Flash lists the lower rate for Synthesis (per 1M characters). Both live rate cards are on this page and always match what the API charges.

Can I switch between TTS 2 Flash and TTS 2 without rebuilding my integration?

Yes. Both models use POST /v1/audio/speech with the same EmpirioLabs API key, so most integrations switch by changing the model value. Check the parameters table on this page first if you rely on a model-specific parameter.

Can I try TTS 2 Flash and TTS 2 in the browser before integrating?

Yes. Open each model in the EmpirioLabs playground and run the same prompt on both, with the parameters the API exposes.

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