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Speech recognition

Speech recognition resources control how the agent processes user speech input on the voice channel.

These resources live under voice/speech_recognition/ and are used to tune how the agent listens, recognises, and post-processes spoken input.

Location

voice/speech_recognition/
├── asr_settings.yaml
├── keyphrase_boosting.yaml
└── transcript_corrections.yaml

All three files are voice-specific. Only asr_settings.yaml is the core settings file; the others are optional.

What speech recognition controls

  • ASR settings

    Configure global speech-recognition behavior such as barge-in and latency/accuracy style.

  • Keyphrase boosting

    Bias recognition toward specific words or phrases.

  • Transcript corrections

    Apply regex-based corrections after speech recognition.

ASR settings

ASR settings are defined in:

voice/speech_recognition/asr_settings.yaml

These settings control global speech-recognition behavior for the voice channel.

Fields

Field Type Description
barge_in bool Whether the user can interrupt the agent while it is speaking. Default: false.
interaction_style string Controls the latency/accuracy trade-off. Default: balanced.

Example

barge_in: false
interaction_style: balanced

Interaction styles

Style Behavior
precise Higher accuracy, higher latency
balanced Default balance of speed and accuracy
swift Faster responses, slightly lower accuracy
sonic / turbo Lowest latency

Keyphrase boosting

Keyphrase boosting is defined in:

voice/speech_recognition/keyphrase_boosting.yaml

It biases the recognizer toward specific words or phrases, which is useful for:

  • brand names
  • product names
  • specialist terminology
  • domain-specific jargon

Structure

A keyphrases list where each entry includes:

Field Required Description
keyphrase Yes The word or phrase to boost
level No Boost strength: default, boosted, or maximum

Example

keyphrases:
  - keyphrase: PolyAI
    level: maximum
  - keyphrase: reservation
    level: boosted
  - keyphrase: check-in
    level: default

Transcript corrections

Transcript corrections are defined in:

voice/speech_recognition/transcript_corrections.yaml

These rules post-process ASR output to fix common misrecognitions.

They are especially useful for:

  • email domains
  • repeated digits
  • domain-specific phrases
  • spoken forms that should be normalized into machine-friendly text

Structure

A corrections list where each entry includes:

Field Required Description
name Yes Identifier for the correction group
description No Explains what the correction fixes
regular_expressions Yes Regex rules used for correction

Each regex rule can include:

Field Required Description
regular_expression Yes Pattern to match
replacement Yes Replacement text
replacement_type No full or partial / substring

Example

corrections:
  - name: Email domain fix
    description: Correct common email domain misrecognitions
    regular_expressions:
      - regular_expression: at gmail dot com
        replacement: "@gmail.com"
        replacement_type: full
      - regular_expression: at hotmail dot com
        replacement: "@hotmail.com"
        replacement_type: full

  - name: Number normalization
    description: Normalize spoken numbers to digits
    regular_expressions:
      - regular_expression: \bdouble (\d)\b
        replacement: \1\1
        replacement_type: partial

Best practices

  • use keyphrase_boosting for terms the recognizer is likely to miss
  • keep boosted keyphrases focused and specific
  • use transcript corrections for common, repeated recognition errors
  • avoid overly broad regex rules that may alter normal input unexpectedly
  • choose the ASR interaction style deliberately based on latency and accuracy needs

Use the lightest possible intervention

Start with the default settings, then add boosting or transcript corrections only where recognition problems are actually recurring.

  • Voice settings

    See how speech recognition fits into the wider voice-channel configuration. Open voice settings

  • Response control

    Configure what happens to output before it is spoken. Open response control