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You can control how a Retell agent pronounces specific words or phrases. Choose IPA, CMU, Mandarin Pinyin, or Cantonese Jyutping when the selected voice model supports it. To use the feature, you set a pronunciation dictionary on the agent. The dictionary is a list of entries, and each entry has:
  • Word or phrase to be annotated. For example, actually.
  • Phonetic alphabet supported by the selected voice.
  • Phoneme with the pronunciation in the selected alphabet.
For example: Use tone numbers 1–5 for Pinyin and 1–6 for Jyutping. Separate syllables with spaces.

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Voice support

Which phonetic alphabets you can use depends on the selected voice provider and its effective voice model. The dashboard shows the supported alphabets under Pronunciation in the agent’s speech settings. See supported languages by provider for voice-model language restrictions. If an ElevenLabs voice uses Auto, an English-only agent resolves to Flash v2 and supports IPA and CMU. Agents that use other languages resolve to a newer ElevenLabs model that does not support pronunciation dictionaries. The dashboard displays the resulting support. If the selected voice or model doesn’t support an entry’s alphabet, Retell preserves the entry but doesn’t apply it.

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How many entries can I add?

The pronunciation dictionary is a list on the agent — you can add multiple entries and there is no fixed cap enforced by the API. In practice:
  • Add one entry per word or short phrase you want to override. Each entry needs its own word, alphabet, and phoneme.
  • Keep the dictionary focused on words the model actually mispronounces (uncommon proper nouns, brand names, technical terms, foreign words). Overriding common words can produce unnatural speech.
  • Use a unique word value for each entry. The API rejects updates that contain duplicate word values.
  • Very large dictionaries can push the agent payload close to request size limits when calling update-agent. If you hit that, split entries across agents or trim rarely used words.

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Finding the phonetic pronunciation

You can search online to find the phonetic pronunciation of a word, or use tools like: