eleven_turbo_v2_5 model delivers natural-sounding English speech with the lowest latency of any ElevenLabs model.
Quick config
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.
Key settings
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 avoice_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
Which model should I use — Turbo or Flash?
Which model should I use — Turbo or Flash?
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.How do I find a voice_id?
How do I find a voice_id?
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.Can I use a cloned voice?
Can I use a cloned voice?
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.The audio sounds choppy. What should I do?
The audio sounds choppy. What should I do?
Increase
buffer_size to 350–400. Choppy audio usually means the first audio chunk starts before ElevenLabs has generated enough audio to stream smoothly.Related
- Audio Tab — configure synthesizer in the dashboard
- Clone Voices — create a custom voice
- Import Voices — use existing ElevenLabs voices
- Cartesia — alternative low-latency synthesizer
- Latency — how synthesis affects response time