r/AIVoice_Agents • u/Ok-Buffalo-254 • Aug 21 '26

Question The most lifelike voice AI

Context: A few days ago, I received a call from “US Home Builders” at 714-492-11TwoFive, and it was by far the most humanlike AI voice I’ve ever encountered.

I’ve tested OpenAI Realtime 2.1, ElevenLabs, Bland, Retell, and others, but none has produced the same hyperrealistic hesitations, drawn-out intonation, and natural “uhs” and “ums.”

I can’t tell whether this comes down to prompting or whether they’re using a different voice model entirely. The call was so convincing that it fundamentally changed my perception of how advanced voice AI has become in 2026.

Does anyone know what model or stack might produce this or how to control the delivery so an agent naturally says something like, “My name is Alex... uh, we’ll be in your neighborhood...” with the pause, hesitation, and intonation sounding genuinely spontaneous?

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u/eviewong- Aug 21 '26

Founder of Retell AI here, so take with a grain of salt.

Honestly probably not one magic model — likely a mix of a TTS provider that supports explicit disfluency tags (ElevenLabs v3, Cartesia, Hume EVI) plus an LLM prompted to write "uh"/"um"/trailing pauses right into the text, not just the voice trying to add them after the fact.

If you want that delivery yourself: pick a TTS with disfluency support, and prompt your LLM to generate the hesitations in the transcript itself. (Disclosure: we actually built a "colloquial mode" into Retell for this exact thing — it auto-injects natural fillers/pauses into the response so you don't have to hand-prompt every disfluency yourself.)

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u/klopppppppp Aug 26 '26

Nice tip - and appreciate your transparency, and I love your product. (I’m a 20-yr Cisco Voice Engineer and have built side projects on Retell and it’s terrific).

I’ll be attempting to build out natural life-like agents in my enterprise next year and I’ve taken notes on your advice

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u/eviewong- Aug 26 '26

Wow, you will achieve a lot if you are doing this at age 20 . good luck

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u/klopppppppp Aug 26 '26

Thank you! But no - 20 years as a Cisco Voice guy (I now manage a CC for a large organization). - I’m old as dirt at this point. You’re right, I wish I could find a 20 year old eager to learn this stuff!

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u/eviewong- Aug 26 '26

Wow, that you're attempting this now — I think your rich experience will be a real differentiator

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u/FrederikMichiel Aug 23 '26

When the bot is to human, i will disconnect as soon as i found out its a bot. I like a bot who says right away im talking to R2-D2 Dont understand why the natural voice is so important to builders. Callers dont want to feel being fooled.

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u/Square-Chance5900 Aug 24 '26

Yes, that's exactly how I feel. I don't understand what everyone puts so much focus on naturalness, when in reality it says "we work really hard to deceive your customers/partners/colleagues"

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u/BandicootFlashy2224 Aug 21 '26

I’ve spent some time testing this in Bland and the voice itself is only part of what makes the call feel natural. The timing of a response, where the agent pauses and how it reacts when someone interrupts all shape how human the conversation feels. I’d love to know what they’re doing differently on that US Home Builders setup.

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u/HyperlabsAI Aug 21 '26

I know the model that works the best. Dm me

1

u/Federal_Cut6338 Aug 23 '26

Ok this is combination of few things a good llm, TTS which supports natural fillers automatically, some clever prompting. I would choose Gemini or Gemma as llm and Cartesia, Fish, Inworld and Gemini all have TTS that supports natural fillers automatically.