Agent STT configuration

Configuration is passed in StartRecognition and is split across two levels of the payload: audio_format at the top level, and transcription_config.

Agent STT is in Preview.

Audio format

Only pcm_s16le at 8000 Hz or 16000 Hz is supported. Other encodings such as pcm_f32le and mulaw, and other sample rates such as 44100 Hz, may be silently accepted by the API but will not produce correct output.

Field	Notes
type	Must be raw
encoding	Must be pcm_s16le (16-bit signed little-endian PCM)
sample_rate	Must be 8000 or 16000

For example:

{ "type": "raw", "encoding": "pcm_s16le", "sample_rate": 16000 }

Transcription config

The transcription_config object accepts the following fields.

Field	Default	Notes
language	en	All supported languages
output_locale	—	Output locale, for example en-US
additional_vocab	—	Custom vocabulary entries
punctuation_overrides	—	Custom punctuation rules
domain	—	Domain-specific tuning, for example medical
enable_entities	false	Entity detection
enable_partials	true	Emit partial segments during speech
diarization	speaker	Speaker diarization; set to none to disable
volume_threshold	—	Minimum audio volume to process

For the languages available, see Transcription languages. For the medical domain, see Medical domain.

Speaker diarization config

The transcription_config.speaker_diarization_config object accepts the following fields. All of them require diarization to be set to speaker.

Field	Default	Notes
max_speakers	—	Maximum number of speakers to track
speaker_sensitivity	—	Sensitivity of speaker separation
prefer_current_speaker	—	Bias toward the most recently active speaker
known_speakers	—	Pre-enrolled speaker identifiers for cross-session recognition

For how to obtain and use known_speakers, see Speaker focus and identification.

Unsupported fields

The following fields are rejected if present in an agent STT request.

Field	Notes
translation_config	Not supported on agent endpoints
audio_events_config	Not supported on agent endpoints