Partial transcripts provide a low-latency streaming transcription as words are spoken, offering immediate insights before the final, high-accuracy transcript is ready. To enable partial transcripts, add the receive_partial_transcripts property to the messages_config object: 
{
  "encoding": "wav/pcm",
  "sample_rate": 16000,
  "bit_depth": 16,
  "channels": 1,
  "language_config": {
    "languages": ["en"],
    "code_switching": false
  },
  "messages_config": {
    "receive_partial_transcripts": true,
    "receive_final_transcripts": true
  }
}
With this configuration, you will receive both partial transcripts as they are generated and the final, most accurate version of each utterance. To reduce the total response time and create a more fluid user experience, partial transcripts use a faster, smaller model than the one used for final transcripts, trading a small amount of accuracy for a large gain in latency (< 100ms).
Partial transcripts accuracy deteriorates when multiple languages and/or code switching are enabled. For best results, limit the number of languages.
When receive_partial_transcripts is true, the real-time API will send transcript messages for both intermediate and final results. To distinguish between them, the message payload includes the is_final boolean field.
  • "is_final": false: The message contains a partial transcript, which is subject to change.
  • "is_final": true: The message contains the final, most accurate transcript for an utterance. This transcript will not change.
In the same utterance, the partial and final transcripts share the same data.id.