Skip to main content
ElevenLabs is Bolna’s default voice synthesizer. The eleven_turbo_v2_5 model delivers natural-sounding English speech with the lowest latency of any ElevenLabs model.

​
Quick config

To use your own ElevenLabs account (for voice cloning or custom voices), connect it at platform.bolna.ai/auth/elevenlabs.

​
Supported models

eleven_turbo_v2_5 is the standard choice for production agents. Use eleven_flash_v2_5 when you need the absolute lowest time-to-first-audio. eleven_v3_conversational is ElevenLabs’ most expressive model and supports 74 languages. It ignores speed, style and similarity_boost, and accepts only three temperature values (see below).

​
Key settings

​
Eleven v3 settings

eleven_v3_conversational takes a narrower set of voice settings than the Turbo and Flash models:

​
buffer_size guidance

buffer_size controls the trade-off between first-word latency and audio smoothness:
  • 100–150 — fastest first word; can sound choppy if ElevenLabs response is slow
  • 250 — balanced default; works well for most agents
  • 400+ — smoothest speech; higher latency to first word

​
Choosing a voice

ElevenLabs voices are identified by a voice_id. The voice name field is for reference only — Bolna uses voice_id to select the voice. Browse voices in the ElevenLabs Voice Library. Copy the voice ID from the URL or the voice details panel. Example voices: For a custom or cloned voice, use the voice_id from your ElevenLabs account. See Clone Voices and Import Voices.

​
audio_format by telephony provider

​
FAQ

Use eleven_turbo_v2_5 for most production agents. It has the better quality/latency balance. Use eleven_flash_v2_5 only if your primary constraint is time-to-first-audio and you’ve measured that Turbo is too slow. Use eleven_v3_conversational when expressiveness is the priority; it is the most expressive of the three, and Turbo remains the lower-latency option.
eleven_v3_conversational ignores speed, style and similarity_boost; the model does not act on them. Only temperature (stability) has an effect, and it accepts three values: 0.0, 0.5 and 1.0. Anything else is rounded to the nearest of those. Use Turbo or Flash if you need speed control.
In the ElevenLabs dashboard, open any voice and look at the URL — the ID is the path component after /voice/. Alternatively, list voices via the ElevenLabs API. Always store the voice_id, not just the name; names can change.
Yes. Clone your voice in ElevenLabs, connect your ElevenLabs account to Bolna, then set voice_id to your cloned voice’s ID. See Clone Voices.
Increase buffer_size to 350–400. Choppy audio usually means the first audio chunk starts before ElevenLabs has generated enough audio to stream smoothly.