VAPI•4mo ago

Times read in English instead of German in TTS output

No matter what I do, times are pronounced in English. The German language is PERFECT, then a time comes along and ‘18:00 Uhr’ becomes ‘eighteen Uhr’. I've already tried:

Changing 18:00 to 18 o'clock,
Specifying in the prompt that it should pronounce all numbers humanly and completely with examples,
3 different Elevenlabs that usually work really well (e.g. voice ID mDRP1h6KfUD1XAUJxqr0),
Different Elevenlabs models (Turbo v2.5 and Multilingual v2)

When using the same voice in Elevenlabs, everything sounds good.

Vapi Support BotAPP•9/3/25, 11:53 AM

Thank you for the detailed description. To help narrow down the issue, could you confirm whether you have tried disabling the voice formatting plan in Vapi (by setting voice.chunkPlan.formatPlan.enabled = falsevoice.chunkPlan.formatPlan.enabled = false) to see if the times are then pronounced correctly in German? This can help determine if the formatting layer is causing the English pronunciation of times.

Example:

"voice": {
  "chunkPlan": {
    "formatPlan": {
      "enabled": false
    }
  }
}

"voice": {
  "chunkPlan": {
    "formatPlan": {
      "enabled": false
    }
  }
}

Source:

Voice formatting plan

⤵️ Mention @Vapi Support Bot for follow-ups 🐥

Lltd-scarlet Thank you for the detailed description. To help narrow down the issue, could you...

moderate-tomatoOP•9/3/25, 12:03 PM

Thanks, yeah that could be the issue! How do I modify the JSON in a workflow based bot?

VapiAPP•9/5/25, 6:56 AM

Hi 2_click,

For times to be read in German in your Text-to-Speech (TTS) output using Inworld voices, ensure that the TTS language and model are set correctly. You can customize the language to German in the Inworld Voice settings. Check the settings to ensure that the language is set to German rather than English.

Here's a quick guide to double-checking your settings:

Navigate to your configuration settings.
Under the Inworld voice provider settings, ensure the language is set to German.
Verify your TTS model supports German output.

For more details about configuring Inworld Voice, you can refer to the Inworld Voice Configuration.

If the issue persists despite these settings, please make sure your configurations are saved and applied correctly.

here are the best practices for handling time formatting in voice responses:

Present time in a clear format using words instead of numbers. For example:

"vier Uhr dreißig" instead of "16:30""achtzehn Uhr" instead of "18:00"

"vier Uhr dreißig" instead of "16:30""achtzehn Uhr" instead of "18:00"

In your prompt, include specific guidelines for time formatting. For example:

[Response Guidelines]Present time in a clear format (e.g. Four Thirty PM)Speak dates and times gently using English words instead of numbers

[Response Guidelines]Present time in a clear format (e.g. Four Thirty PM)Speak dates and times gently using English words instead of numbers

When working with ElevenLabs voices, ensure you're using the Multilingual v2 model for German language support.

If you're still experiencing issues with time pronunciation, try:

Writing out the time completely in words in your responses
Using alternate time formats like "achtzehn hundert Uhr"
Avoiding colons or other special characters in time expressions

Times read in English instead of German in TTS output

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