Designing Real-Time Avatar Conversations: Why Speech-to-Text Accuracy Matters
When you speak to someone, you expect to be heard — and understood. But in an AI-powered avatar simulation, that process depends on one thing: how accurately your voic...
When you speak to someone, you expect to be heard — and understood. But in an AI-powered avatar simulation, that process depends on one thing: how accurately your voice is turned into text.
At Pxl-Persona, we build avatars that listen, think, and respond in real time. Whether someone is preparing for an interview, practicing a sales pitch, or training for a clinical conversation, one thing is constant: speech-to-text accuracy makes or breaks the experience.
What Is Speech-to-Text — and Why Does It Matter?
Speech-to-Text (STT) is the technology that transcribes spoken words into written text.
In real-time avatar interactions, it’s the first link in the chain:
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The user speaks
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The system transcribes their words
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The AI interprets the meaning
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A response is generated, voiced, and animated back to the user
If STT fails — even slightly — everything downstream is affected:
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The avatar might misunderstand the question
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The reply might feel off-topic or impersonal
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The user’s confidence and immersion are lost
That’s why we’ve made STT a core focus of how we build conversations.
What We Use at Pxl-Persona
For internal applications, we use Whisper, an open-source model by OpenAI, running on our high-performance GPUs. This gives us:
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Fast transcription
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High accuracy, even with varied accents
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Smooth integration into our avatar pipeline
But we don’t stop there.
Pxl-Persona is built to be flexible. We can:
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Hook into cloud-based APIs (e.g. Google, AWS, Deepgram)
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Adapt the system based on environment (e.g. kiosk vs classroom)
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Choose STT models depending on context and latency needs
Training Voices, Tuning Accents
We’ve gone further — using STT not just for understanding, but also for building more relatable avatars.
Custom Voice Modelling
Our team can:
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Record and sample a person’s voice
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Train it into an AI-generated voice model
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Feed that voice back into our avatars — safely, and with emotion control
This is ideal for:
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Simulating real professionals (e.g. NHS staff, teachers)
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Creating familiar voice experiences for users
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Localising avatars to feel more believable
Researching Accent Models
We’re actively researching how to blend multiple voices with shared accents to create regional voice models.
Why? Because users connect with voices that reflect their world.
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A Scouse accent for Liverpool-based schools
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A Glasgow tone for Scottish learners
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A London variation for urban youth
This isn’t just about realism — it’s about inclusion and connection.
Understanding Industry Jargon
Pxl-Persona is building a bank of domain-specific terms and acronyms across industries.
For example:
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“NEBOSH” in construction
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“CPT” in healthcare
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“C#” in programming (not “C-hashtag”)
These are terms most language models don’t understand natively. But with our data capture and prompt engineering, we make sure avatars know what users mean — and how to say it correctly.
This is especially critical in interview training, where misunderstanding a word could cost confidence — or a job.
Visual Support & Multimodal Interactions
Not every user hears clearly — and some may prefer reading.
That’s why every Pxl-Persona avatar session includes:
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Live captions of avatar speech
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A full UI with transcripts and buttons for pre-loaded questions
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Support for text-only interaction if needed
This makes our avatars accessible, multimodal, and suitable for users with SEND needs or non-native English speakers.
Testing, Tuning, and Getting It Right
As with all AI systems, STT is not 100% perfect. But that’s where our team excels.
We:
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Work closely with domain experts to identify misheard terms
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Review session logs for problem phrases
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Continuously update prompts and vocab banks
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Prioritise testing across accents and noisy environments
Our goal isn’t just to transcribe words.It’s to make sure users feel heard.
Final Thoughts
In real-time conversations with avatars, Speech-to-Text accuracy is everything.
It’s the difference between feeling like you're talking to a smart system… or getting frustrated by something that "doesn't get you".
At Pxl-Persona, we’re designing avatar conversations to be:
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Fast
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Accurate
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Inclusive
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Adaptable
Because when users feel understood — they engage, reflect, and grow.
How Our Avatars Actually Work
Behind the scenes of voice, streaming, and animation.