ElevenLabs

ElevenLabs tuning is passed in synthesizer.options. Most of it lives under a nested voice_settings object, matching ElevenLabs’ own API.

1 {
2   "verb": "say",
3   "text": "Thanks for calling, how can I help you today?",
4   "synthesizer": {
5     "vendor": "elevenlabs",
6     "language": "en",
7     "voice": "21m00Tcm4TlvDq8ikWAM",
8     "options": {
9       "optimize_streaming_latency": 3,
10       "voice_settings": {
11         "stability": 0.5,
12         "similarity_boost": 0.5,
13         "use_speaker_boost": true
14       }
15     }
16   }
17 }

Options

optimize_streaming_latency

number

Latency optimisation level. Defaults to 3. Higher values reduce time-to-first-audio, trading off some quality — 0 disables the optimisation entirely.

pronunciation_dictionary_locators

array

Pronunciation dictionaries to apply, in ElevenLabs’ locator form.

voice_settings

voice_settings.stability

number

0.0 – 1.0, defaults to 0.5. Lower values make delivery more varied and expressive; higher values make it more consistent and monotone.

voice_settings.similarity_boost

number

0.0 – 1.0, defaults to 0.5. How closely the output tracks the original voice.

voice_settings.style

number

Style exaggeration. Raising it increases expressiveness but costs latency, and can destabilise the voice at high values.

voice_settings.use_speaker_boost

boolean

Defaults to true. Improves similarity to the original speaker at a small latency cost.

voice_settings.speed

number

Speaking rate.

stability and style pull against each other. If you raise style for expressiveness and the voice starts to wander or produce artifacts, raise stability rather than lowering style back down.

Streaming

ElevenLabs supports TTS streaming with word-level alignment. It has no cancel message, so barge-in is handled by dropping and re-establishing the connection.