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The Humanness Index™
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The Humanness Index™

The open benchmark for how human voice AI sounds, so you can pick the model that passes. Built by Vapi.

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Code is Apache-2.0. Standings data is CC BY 4.0. Audio clips and source voices are licensed recordings, all rights reserved. Provider logomarks belong to their respective owners and are used nominatively. “The Humanness Index™” name and logo are Vapi trademarks; see TRADEMARKS.md.

  1. Humanness Index™
  2. ElevenLabs
  3. Eleven v4

Humanness Index™ · TTS model

ElevenLabs

ElevenLabs Eleven v4

by ElevenLabs

Eleven v4 is the quality focused member of the v4 family, released on September 28, 2026.

Rank
#13
Humanness
71
Likely rank
Provisional
Blind votes
0

Standings as of Oct 27, 2026, 19:01 UTC

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A real arena clip: a cloned source voice reading a customer support prompt at phone quality.

Eleven v4 key stats

Latency (measured)
671 ms1
Languages
90+2
Price / 1M chars
$803
Streaming
Yes4
Voice cloning
Instant voice cloning5
Released
September 28, 20266
  1. Vapi streaming benchmark (50 trials per model) (checked 2026-10-27) Median of 50 sequential Text to Dialogue WebSocket trials after two discarded warm ups, October 27, 2026; PCM 24 kHz; Clara v4 Instant Voice Clone; stability 0.35, similarity 0.95. Includes network RTT, excludes WebSocket connection setup.
  2. elevenlabs.io/docs/overview/models (checked 2026-10-27)
  3. elevenlabs.io/pricing/api (checked 2026-10-27) Published ElevenAPI rate of $0.08 per 1K characters, normalized to $80 per 1M. Enterprise contract rates may differ.
  4. elevenlabs.io/docs/api-reference/text-to-dialogue/ttd-websocket (checked 2026-10-27)
  5. elevenlabs.io/v4 (checked 2026-10-27) The benchmark uses fresh Instant Voice Clones from 30 second licensed reference samples, rather than the earlier models' professional clones.
  6. elevenlabs.io/blog/eleven-v4 (checked 2026-10-27)

Background

Eleven v4 is the quality focused member of the v4 family, released on September 28, 2026. ElevenLabs describes a new architecture with greater control over emotional delivery, more reliable speaker identity, and support for more than 90 languages. The Index evaluates its plain English scripted output using the same licensed source speakers as every other model.

Sources: elevenlabs.io, elevenlabs.io

On the Index

The arena clips use four fresh Instant Voice Clones made from 30 second excerpts of the licensed Clara, Emma, Godfrey, and Nelliot recordings. Each clone reads all 20 frozen prompts through the Text to Dialogue WebSocket with stability 0.35 and similarity 0.95. Our October 27, 2026 benchmark measured a median of 671 ms to first audio over 50 sequential PCM streaming trials after two discarded warm ups, using the same Clara clone and including network RTT.

Sources: elevenlabs.io, elevenlabs.io

Position in the rankings

Standings as of Oct 27, 2026, 19:01 UTC

RankProviderModelHumannessLatency
#11ElevenLabsElevenLabsFlash v276226 ms
#12CartesiaCartesiaSonic 3.671101 ms
#13ElevenLabsElevenLabsEleven v471671 ms
#14ElevenLabsElevenLabsEleven v4 Turbo71158 ms
#15MurfMurfFalcon 2.171117 ms

See the full Humanness Index™ rankings

Frequently asked questions

How is Eleven v4 tested on the Humanness Index™?
Listeners hear Eleven v4 against another model in a blind head to head round, both voices reading the same customer support prompt from the same cloned source voice, and they pick whichever sounds more human. Its Humanness score derives purely from those votes.
How does Eleven v4 differ from Eleven v4 Turbo?
Eleven v4 is tuned for produced speech where quality is the priority. Eleven v4 Turbo targets realtime speech generation. Both use the same four cloned benchmark speakers and the same 20 English prompts here; synthesis latency is measured separately from listener votes.

Keep exploring

ElevenLabsElevenLabsAll ElevenLabs models on the IndexElevenLabsTurbo v2Rank #10 · Humanness 77ElevenLabsTurbo v2.5Latency 265 msElevenLabsFlash v2Rank #11 · Humanness 76ElevenLabsFlash v2.5Rank #19 · Humanness 69ElevenLabsEleven v3Rank #1 · Humanness 98ElevenLabsMultilingual v2Latency 1006 msElevenLabsEleven v4 TurboRank #14 · Humanness 71

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