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Response control resources process the agent’s output before it is spoken.

They are used to adjust spoken output by:
  • fixing pronunciation
  • intercepting or blocking phrases before speech synthesis
These resources are voice-channel specific and live under voice/response_control/.

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Location

voice/response_control/
├── pronunciations.yaml
└── phrase_filtering.yaml
Both files are optional.

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What response control does

Pronunciations

Fix how words, abbreviations, or phrases are spoken by TTS.

Phrase filtering

Block or intercept phrases before they are spoken.

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Pronunciations

Pronunciation rules live in: 
voice/response_control/pronunciations.yaml
These rules are applied before speech synthesis and are useful when the agent says something incorrectly.

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What a pronunciation rule contains

Each item in the pronunciations list can include:
FieldRequiredDescription
regexYesRegex pattern to match in the output text
replacementYesReplacement text for speech synthesis
case_sensitiveNoWhether matching is case-sensitive
language_codeNoRestrict the rule to a specific language
descriptionNoNotes about the rule
Rules are ordered, so list position matters.

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Example

pronunciations:
  - regex: "\\bDr\\."
    replacement: Doctor
    case_sensitive: true

  - regex: "\\bMr\\."
    replacement: Mister
    case_sensitive: true

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Phrase filtering

Phrase-filtering rules live in: 
voice/response_control/phrase_filtering.yaml
These rules can block or intercept phrases before they are spoken. A matched phrase can also trigger a function.

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What a phrase filter contains

Each item in the phrase_filtering list can include:
FieldRequiredDescription
nameYesIdentifier for the filter
descriptionNoExplains what the filter does
regular_expressionsYesRegex patterns to match
say_phraseNoWhether to still speak the matched phrase
language_codeNoRestrict the filter to a specific language
functionNoGlobal function to call when a match occurs

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Example

phrase_filtering:
  - name: Block Profanity
    description: Blocks profane words from being spoken
    regular_expressions:
      - "\\bbadword\\b"
    say_phrase: false

  - name: Competitor Mention Handler
    description: Intercept competitor names and redirect
    regular_expressions:
      - "\\bcompetitor_name\\b"
    say_phrase: true
    function: handle_competitor_mention

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When to use response control

Use response control when standard prompting is not enough and you need a more deterministic layer before output is spoken. Typical cases include:
  • fixing abbreviations or domain-specific terms in TTS
  • preventing profanity from being spoken
  • reducing the risk of unsafe or brand-damaging output
  • intercepting special phrases and triggering code

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Best practices

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For pronunciations

  • keep regex patterns targeted and readable
  • use language-specific rules when pronunciation should vary by locale
  • rely on rule ordering deliberately where multiple patterns could overlap

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For phrase filters

  • use phrase filters for safety and brand protection
  • keep regex patterns specific to avoid false positives
  • only attach a function when you need a real side effect
  • ensure the function value refers to a valid global function, not a flow function
Phrase filters are powerfulAn over-broad regex can suppress or intercept normal output unexpectedly. Keep filters as specific as possible.

Voice settings

See where response control fits within the broader voice-channel configuration.

Functions

Learn how global functions can be triggered from phrase filters.
Last modified on July 9, 2026