OpenAI speech provider

An OpenAI speech provider lets Live Hub use your OpenAI account for text-to-speech (TTS), speech-to-text (STT), or both.

OpenAI's advanced configuration parameters are set on a bot connection rather than on the provider. See Configure advanced parameters at the bot connection level.

Add an OpenAI speech provider

To add an OpenAI speech provider:

  1. In the 'Authentication key' field, enter your OpenAI API key.

  2. Under Text-to-Speech (TTS):

    • From the 'TTS Model' drop-down list, select gpt-4o-mini-tts.
    • In the 'Initial buffer time (MS)' field, enter how much audio to buffer before playing it to the caller, from 0 to 5000. Buffering absorbs the model's start-up delay so playback does not stutter.

  3. Under Speech-to-Text (STT), from the 'STT Model' drop-down list, select whisper-1, gpt-4o-transcribe, gpt-4o-mini-transcribe, or gpt-realtime-1.5.

  4. Click Create.

    The OpenAI speech provider fields

Only the sections for the speech types you selected appear.

Configure advanced parameters at the bot connection level

Synthesis parameters go under ttsPassthruConfig in the JSON editor on the bot connection's Advanced tab, and Live Hub merges them into the request it sends to OpenAI. See Manage bot connections.

The full set of text-to-speech parameters is Create Speech in OpenAI's audio API documentation.

{
    "ttsPassthruConfig": {
        "speed": 1.25
    }
}

Setting model here overrides the 'TTS Model' drop-down list on the provider.

Set the speaking style

ttsInstructions tells the model how to speak. It goes on the same Advanced tab, alongside ttsPassthruConfig rather than inside it:

{
    "ttsInstructions": "Speak in a cheerful and positive tone."
}

Tune recognition

Recognition parameters go under sttPassthruConfig on the same tab. Live Hub sends them in the session it opens with OpenAI's realtime API, so they take the shape that API defines:

{
    "sttPassthruConfig": {
        "audio": {
            "input": {
                "noise_reduction": {
                    "type": "near_field"
                }
            }
        }
    }
}

Turn-taking

Live Hub ends the caller's turn after a period of silence. One field on the bot connection's Settings tab, under Speech-to-Text (STT) Settings, sets how long Live Hub waits. The field has a bot parameter behind it, which you can set on the Advanced tab instead:

Field Bot parameter
'End-of-turn timeout (ms)' sttSegmentationSilenceTimeoutMs

The default is 800 ms, and the range is from 100 to 5000 ms. If the timeout is too short, Live Hub ends the turn while the caller is still speaking. If the timeout is too long, the bot waits after the caller has finished.

Language and voice

You select the language and the voice per bot connection, on its Settings tab, not on the provider. See Manage bot connections.