Audio Configuration

A variety of microphones can be used for speech to text workflows. Optimal configuration of such devices depends on environmental factors and use case. This page provides guidance of configuration best practice for common scenarios. Be sure to adapt for your local needs.

See audio format requirements for full details on allowable MIME types and supported audioFormat configuration.

Microphone Configuration

Dictation

Setting	Recommendation	Rationale
echoCancellation	Off	Ensure clear, unfiltered audio from near-field recording.
autoGainControl	Off	Manual calibration of microphone gain level provides optimal support for consistent dictation patterns (i.e., microphone placement and speaking pattern). Recalibrate when dictation environments change (e.g., moving from a quiet to noisy environment). Recommend setting input gain with average loudness around –12 dBFS RMS (peaks near –3 dBFS) to prevent audio clipping.
noiseSuppression	Mild (-15dB)	Removes background noise (e.g., HVAC); adjust as needed to optimize for your environment.

Ambient Conversation

Setting	Recommendation	Rationale
echoCancellation	On	Suppresses “echo” audio that is being played by your device speaker, e.g. remote call participant’s voice + system alert sounds.
autoGainControl	On	Adaptive correction of input gain to support varying loudness and speaking patterns of conversational audio.
noiseSuppression	Mild (-15dB)	Removes background noise (e.g., HVAC); adjust as needed to optimize for your environment.

Maintain average loudness around –12 dBFS RMS with peaks near –3 dBFS for optimal speech-to-text normalization.

Channel Configuration

Choosing the right channel configuration ensures accurate transcription, speaker separation, and diarization across different use cases.

Audio type	Workflow	Rationale
Mono	Dictation or in-room doctor/patient conversation	Speech to text models expect a single coherent input source. Mono also reduces bandwidth and file size without affecting accuracy.
Multichannel (dual mono)	Telehealth or remote doctor/patient conversations	Assigns each participant to a dedicated channel, allowing the speech to text system to perform accurate speaker attribution. Provides better control over noise suppression and improves transcription accuracy when voices overlap.

Mono input supports transcription with diarization; however, speaker separation may be unreliable when there is not clear turn-taking in the dialogue.Multichannel input (two audio channels, one per participant, in telehealth workflow) provides opportunity for improved speaker separation and labeling.

Streams Endpoint

Mono Audio Stream with Diarization

{
"type": "config",
"configuration": {
    "transcription": {
    "primaryLanguage": "en",
    "diarize": true,
    "isMultichannel": false,
    "participants": [
        {"channel": 0, "role": "multiple"}
      ]
    },
    "mode": {
    "type": "facts",
    "outputLocale": "en"
    }
  }
}

Multichannel Audio Stream with Participants

{
"type": "config",
"configuration": {
    "transcription": {
    "primaryLanguage": "en",
    "diarize": false,
    "isMultichannel": true,
    "participants": [
        {"channel": 0, "role": "Doctor"},
        {"channel": 1, "role": "Patient"}
      ]
    },
    "mode": {
    "type": "facts",
    "outputLocale": "en"
    }
  }
}

Diarization Disabled

{
"type": "config",
"configuration": {
    "transcription": {
    "primaryLanguage": "en",
    "diarize": false,
    "isMultichannel": false,
    "participants": []
    },
    "mode": {
    "type": "facts",
    "outputLocale": "en"
    }
  }
}

Transcripts Endpoint

Mono Audio File with Diarization

{
"recordingId": "uuid",
"primaryLanguage": "en",
"spokenPunctuation": true,
"isMultichannel": false,
"diarize": true,
"participants": [
    {"channel": 0, "role": "multiple"}
  ]
}

Multichannel Audio File with Participants

{
"recordingId": "uuid",
"primaryLanguage": "en",
"spokenPunctuation": true,
"isMultichannel": true,
"diarize": false,
"participants": [
    {"channel": 0, "role": "doctor"},
    {"channel": 1, "role": "patient"}
  ]
}

Audio File Diarization Disabled

{
"recordingId": "uuid",
"primaryLanguage": "en",
"spokenPunctuation": true,
"isMultichannel": false,
"diarize": false,
"participants": []
}

Audio streaming recommendations


Sample rate 16 kHz	Captures the full range of human speech frequencies, with higher rates offering negligible recognition benefit but increasing computational cost
Audio chunk size of 250 milliseconds	Optimal speed to support both dictation and AI scribing workflows, with sending much smaller chunks more frequently can degrade recognition accuracy without improving latency
Stream at real-time speed	Audio should be streamed at or near real-time speed. Streaming audio faster than real time is not recommended and may cause buffering issues, degraded results, or stream termination. Pace audio chunks according to their actual audio duration.

Additional Notes

Enabling diarization is typically only required on mono audio.
Mono audio with diarization disabled will produce transcripts with one channel (-1), whereas diarized-mono transcripts will have two channels (0, 1).
For multichannel audio, each channel should capture only one speaker’s microphone feed in order to avoid cross-talk or echo between channels.
A maximum of 8 audio channels are supported in a given audio stream or recording.
Keep all channels aligned in time; do not trim or delay audio streams independently.
Ensure each channel contains only one participant’s feed to avoid duplicated transcript content.
Recommended capture format is 16-bit / 16 kHz PCM

Please contact us if you need more information about supported audio formats or are having issues processing an audio file.Additional references and resources:

Endpoints

Features

Best Practices

Guides

Resources

Microphone Configuration

Dictation

Ambient Conversation

Channel Configuration

Streams Endpoint

Transcripts Endpoint

Audio streaming recommendations

Additional Notes

​Microphone Configuration

​Dictation

​Ambient Conversation

​Channel Configuration

​Streams Endpoint

​Transcripts Endpoint

​Audio streaming recommendations

​Additional Notes

Microphone Configuration

Dictation

Ambient Conversation

Channel Configuration

Streams Endpoint

Transcripts Endpoint

Audio streaming recommendations

Additional Notes