Transcriber
OpenAI (STT) logo

OpenAI GPT Realtime Whisper speech-to-text for Bolna AI voice agents

OpenAI's GPT Realtime Whisper streams speech-to-text for a Bolna voice agent, with built-in voice activity detection, noise reduction and a delay setting for accuracy.

stttranscriberopenaispeech-to-textwhisperrealtime
At a glance

How OpenAI (STT) fits in the stack

Best for

Turning noisy phone audio into text the agent can reason over.

Use this layer when

Recognition accuracy, language coverage, and latency matter most.

Connects to

Telephony audio upstream and your LLM downstream.

Voice Stack

Speech-to-text is the listening layer

Speech-to-text is the listening layer

This provider converts raw audio into text in real time. It shapes how accurately the agent hears the caller and how natural the back-and-forth feels.

TelephonyPhone Network
→
STTListener
→
LLMReasoning
→
TTSVoice
→
ToolsActions

Last updated

What is OpenAI speech-to-text used for in a Bolna voice agent?

OpenAI speech-to-text transcribes the caller for your Bolna agent with gpt-realtime-whisper, a streaming model that returns partial text while the caller is still speaking. Voice activity detection is built in, so it finds the start and end of speech without manual setup. A delay setting lets you trade latency against accuracy for accented speech or noisy lines.

How do I set up OpenAI speech-to-text with Bolna?

  1. Open your agent at platform.bolna.ai and go to the Languages tab.
  2. Under Transcription, set Provider to openai and Model to GPT Realtime Whisper.
  3. Set the language as an ISO 639-1 code, such as en or hi.
  4. Choose a Transcription delay. Keep medium unless you have a reason to change it.
  5. Turn on Noise reduction for call-center or office audio.

In the API, set provider to openai and model to gpt-realtime-whisper, and tune delay and noise_reduction. See the OpenAI transcriber guide in the Bolna docs.

Which delay settings does OpenAI speech-to-text support on Bolna?

delay valueBehavior
minimalFastest, best for simple, clean audio
lowLow latency with good accuracy
mediumDefault, balanced for most agents
highHigher accuracy for accents or background noise
xhighMaximum accuracy, highest latency

Common language codes include en, es, fr, de, hi, pt, ja, it, nl, zh, ko, ar and ru.

What can you build with OpenAI speech-to-text and Bolna?

Agents for accented or noisy callers. Raise delay to high and turn on noise reduction so the model hears more audio before it commits to a transcript.

Fast agents on clean lines. Set delay to minimal or low when audio is clear. Interim transcripts give the LLM an early start on its reply.

OpenAI stacks with your choice of voice. Pair the transcriber with an OpenAI LLM and any voice, such as ElevenLabs or Cartesia. For a single model that hears and speaks, see OpenAI Realtime.

Multilingual agents. GPT Realtime Whisper supports a wide range of languages, including Hindi, Japanese, Chinese, Korean and Arabic.

FAQ

OpenAI (STT) on Bolna: frequently asked questions

Yes. Set the transcriber provider to `openai` and the model to `gpt-realtime-whisper`, shown in the dashboard as GPT Realtime Whisper. It is generally available on Bolna.

It trades speed for accuracy. `minimal` and `low` return text sooner, `medium` is the default, and `high` or `xhigh` give the model more audio for accents or background noise.

No. GPT Realtime Whisper has server VAD built in and detects when speech starts and ends on its own.

No. The transcriber only turns caller audio into text for your chosen LLM and voice. OpenAI Realtime replaces the transcriber, LLM and voice with one model.

Browse this layer

Keep exploring the voice stack

Browse

Speech-to-Text

Speech-to-text converts what callers say into text that your LLM can process. Transcription accuracy and latency directly affect how natural a conversation feels. Bolna supports streaming STT providers optimized for telephony audio, including specialized models for Indian languages.

Browse

Telephony

Telephony providers connect your voice agents to the phone network so they can make and receive real calls. Bolna supports managed integrations with major carriers as well as bring-your-own-carrier via SIP trunking, giving you full control over call routing, number provisioning, and cost.

Browse

Large Language Models

The LLM is the brain of your voice agent. It understands what callers say and decides how to respond. Bolna lets you switch between models like GPT-5.4 mini, Claude and DeepSeek by changing the provider and model in your agent LLM settings, so you can tune for speed, cost or reasoning depth.

Browse

Text-to-Speech

Text-to-speech turns your agent responses into spoken audio. Voice quality shapes how callers perceive your brand. Flat, robotic speech kills trust while natural, expressive voices build it. Bolna integrates with the fastest TTS providers so responses sound human and arrive without awkward pauses.

Browse

Tools & Workflows

Tools let your voice agents take action during a call, not just talk. Book a calendar slot, look up an order through your own API, push a lead into your CRM, or trigger a multi-step automation in Zapier. These integrations turn voice agents from answering machines into workflow engines.

See where OpenAI (STT) fits in your production workflow

Use the demo to walk through provider selection, stack tradeoffs, and the exact workflow you want Bolna to automate.