Audio and voices - Boson

Voices

Select the assistant’s voice with audio.output.voice:

"default" – the built-in preset, always available.
A named preset voice from the Text-to-Speech API.
A custom voice voice_<id>, created via the voices API (POST /v1/audio/voices). See Custom Voices for more details.

Any non-"default" voice is validated when you send session.update; an unknown or inaccessible voice fails the update. To adjust delivery (pace, tone, energy), prompt the model via instructions — e.g. “Speak slowly and calmly.”

{
  "type": "session.update",
  "session": {
    "model": "higgs-realtime",
    "audio": { "output": { "voice": "default" } }
  }
}

Audio format

Supported codecs

Format	Encoding	Sample rates
`audio/pcm` (default)	PCM16, little-endian, mono	8000 / 16000 / 24000 / 48000 Hz (default 24000)
`audio/pcmu`	G.711 μ-law	8000 Hz fixed
`audio/opus`	Opus	24000 Hz internal; `frame_size_ms` of 2.5, 5, 10, 20 (default), 40, or 60

Internal processing always runs at 24 kHz, 16-bit, mono PCM. Audio travels base64-encoded inside JSON events.

Configuration example

{
  "type": "session.update",
  "session": {
    "model": "higgs-realtime",
    "audio": {
      "input":  { "format": { "type": "audio/pcm", "rate": 16000 } },
      "output": { "format": { "type": "audio/pcm", "rate": 16000 } }
    }
  }
}