Custom pronunciation with ElevenLabs V2.5 engine

Hi team,

We are currently using the ElevenLabs V2 voice engine and the custom pronunciation dictionary. We would like to use the V2.5 engine as we feel the voice sounds better and is more consistent than the V2 version, however according to the docs and confirmed with our testing, the custom pronunciations are not obeyed when using V2.5.

This feature only works with English agents using 11Labs voices that selected the eleven turbo v2 (English only) voice model.

We currently have a bit of a clunky workaround in our system prompt as follows, however we would prefer to use the custom dictionary as that is the whole purpose of the feature. We do this because some of our MCP results return words the TTS struggles with, otherwise we would just put the weird phonetic spellings directly in the prompt.

# Word substitution
If you encounter the following words, instead say their replacement word and not the original.

  • “example” should be replaced with “an example replacement”
  • “test” should be replaced with “this is a test”

Is this a limitation on the Retell side or the ElevenLabs side, and is it on the roadmap to bring the custom pronunciation to the V2.5 engine?

Hey @alacer.ben can you share any relevant Call IDs?

Hey @shaw, sorry I didn’t include any call IDs because the documentation specifically said it would not work with the V2.5 engine so it seemed pointless to report a “problem” with something that is explicitly called out in the docs as not working.

My question was more about where the limitation with the pronunciation dictionary lies. Obviously if the limitation is with ElevenLabs then I understand you are not able to do much about that, however if it was a limitation on the Retell side whether it was on the roadmap to bring that functionality to the ElevenLabs V2.5 engine.

In any case, if it helps the team, here are a couple of call IDs.

ElevenLabs v2 (pronunciation working as expected) - call_65663df86dbfb427e3a7f4dbe66
ElevenLabs v2.5 (not obeying custom pronunciation) - call_dddb75971e2052bcf82857468a4

Hey @alacer.ben I have escalated this to team to look. Thanks

Hey @alacer.ben

I checked with the team and Its 11 labs limitations, this is from their docs.