Speaker labeling in recognition results
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Updated at October 20, 2025
In recognition results, the API v3 can specify which speaker uttered each recognized phrase.
Speaker labeling is only available for recognition in FULL_DATA mode for mono records. Recognition results may not feature more than two speakers.
To enable speaker labeling, use the following session parameters:
Python 3
recognize_options = stt_pb2.StreamingOptions(
speaker_labeling=stt_pb2.SpeakerLabelingOptions(
# Enabling speaker labeling
speaker_labeling=stt_pb2.SpeakerLabelingOptions.SPEAKER_LABELING_ENABLED
),
recognition_model=stt_pb2.RecognitionModelOptions(
# Recognition model version
model="general:rc",
audio_format=stt_pb2.AudioFormatOptions(
container_audio=stt_pb2.ContainerAudio(
container_audio_type=stt_pb2.ContainerAudio.WAV
)
),
# Recognition mode
audio_processing_type=stt_pb2.RecognitionModelOptions.FULL_DATA
)
)
You will see channel_tag labels in recognition results, set to 0 or 1. Usually, 0 stands for the left channel and 1, for the right one; however, the numbering may differ.
Each value refers to a single speaker. You can process the results as follows:
Python 3
try:
for r in it:
event_type, alternatives = r.WhichOneof('Event'), None
if event_type == 'final':
alternatives = [a.text for a in r.final.alternatives]
elif event_type == 'final_refinement':
alternatives = [a.text for a in r.final_refinement.normalized_text.alternatives]
else:
continue
print(f'type={event_type}, alternatives={alternatives}, channel_tag = {r.channel_tag}')
except grpc._channel._Rendezvous as err:
print(f'Error code {err._state.code}, message: {err._state.details}')
raise err