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Products that do what Voice bots with 500ms response times does

Last year when GPT-4 was released I started making lots of little voice + LLM experiments. Voice interfaces are fun; there are several interesting new problem spaces to explore. I'm convinced that voice is going to be a bigger and bigger part of how we all interact with generative AI. But one thing that's hard, today, is building voice bots that respond as quickly as humans do in conversation. A 500ms voice-to-voice response time is just barely possible with today's AI models. You can get down to 500ms if you: host transcription, LLM inference, and voice generation all together in one place;…

  1. 1RT
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    Tighter instruction adherence in speech agents

    Feb 2026

  3. 3

    For reliable, production-ready voice agents

    2025

  4. 4IB

    I built a voice agent from scratch that averages ~400ms end-to-end latency (phone stop → first syllable). That’s with full STT → LLM → TTS in the loop, clean barge-ins, and no precomputed responses. What moved the needle: Voice is a turn-taking problem, not a transcription problem. VAD alone fails; you need semantic end-of-turn detection. The system reduces to one loop: speaking vs listening. The two transitions - cancel instantly on barge-in, respond instantly on end-of-turn - define the experience. STT → LLM → TTS must stream. Sequential pipelines are dead on arrival for natural…

    Mar 2026 · ntik.me

  5. 5IB

    Built a ~9M param LLM from scratch to understand how they actually work. Vanilla transformer, 60K synthetic conversations, ~130 lines of PyTorch. Trains in 5 min on a free Colab T4. The fish thinks the meaning of life is food. Fork it and swap the personality for your own character.

    Apr 2026 · github.com

  6. 6AP

    TLDR: We created a personalised Andrej Karpathy tutor that can response to questions about his Youtube videos in sub 1 second responses (voice-to-voice). We do this using a voice enabled RAG agent. See later in the post for demo link, Github Repo and blog write up. A few weeks ago we released the worlds fastest voice bot, achieving 500ms voice-to-voice response times, including a 200ms delay waiting for a user to stop speaking. After reaching the front page of HN, we thought about how we could take this a step further based on feedback we were getting from the community. Many companies were…

    2024 · educationbot.cerebrium.ai

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    Build Powerful Voice Agents

    2025

  8. 8

    Generative AI voice bot for sales, support, and beyond

    2023

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    Retell AI300

    API that helps developers build human-like voice agents

    2024

  10. 10
    GPT-41,161

    LLM that exhibits human-level performance

    2023 · openai.com

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    Open source voice chat infra that rivals GPT-4o

    2024

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    High-quality voice clones with just 60 seconds of audio

    2023

  13. 13

    Combine GPT-3 with custom high quality AI voices

    2021

  14. 14
    GPT-4.5511

    The largest and best model for chat yet in GPT family

    2025

  15. 15
    Botsonic606

    Build custom ChatGPT-like chatbot for your website instantly

    2023

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    GPT-Live211

    Full-duplex voice for ChatGPT

    Jul 2026 · openai.com

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    Build powerful conversational AI agents

    2024

  18. 18

    Premium AI voice quality without the premium price tag.

    2025

  19. 19

    24/7 custom AI livechat + realtime voice chatbot

    2024

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    Clone any voice in 3 seconds – hyper-realistic and free

    2025

  21. 21

    Powerful Conversational AI Agent Builder Platform

    Nov 2025

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    Build AI agents that speak

    2024

  23. 23

    Ultra-realistic AI voices & cloning

    2025

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    Wavel AI289

    Most realistic and natural AI voiceover & dubbing for videos

    2023

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