Improving Transcription Accuracy for Foreign Languages in Retell AI

Overview

Retell AI agents may occasionally face challenges with transcription accuracy and pronunciation when handling foreign languages, such as French, German, Spanish, or other non-English languages. These issues can include inaccurate transcriptions of spoken words, mispronunciations, or missed details like email addresses and phone numbers during interactions or testing. This article outlines common problems and recommended steps to enhance transcription reliability, pronunciation accuracy, and overall performance for multilingual support.

Common Issues

Users have reported the following challenges when using Retell AI agents for foreign language interactions:

• Inaccurate transcription of spoken content, especially in real-time conversations.

• Incorrect pronunciation of words in the target language.

• Missing key details (e.g., email addresses, phone numbers) when prompts or tests are conducted in a foreign language instead of English.

• Persistent errors despite using custom prompts in the foreign language or testing with various models.

These problems are more noticeable in languages with unique phonetic structures, such as French (e.g., accents and liaisons), German (e.g., umlauts and compound words), or Spanish (e.g., rolled 'r's and accents on vowels).

Recommended Solutions

To improve transcription accuracy and pronunciation in foreign languages, follow these step-by-step optimizations. Start with basic adjustments and escalate as needed.

1. Select a Language-Specific Voice from TTS Provider:

   • Use ElevenLabs voices optimized for the target language. These voices are designed for natural pronunciation and can significantly reduce mispronunciation issues.

   • Example for French: Choose a French voice like "Camille" for clear, native-sounding responses.

   • Example for German: Opt for voices like "Elias" or "Felix" to handle German phonetics accurately.

   • Example for Spanish: Use voices such as "Mia" (Latin American) or "Sergio" (European Spanish) to match regional dialects.

2. Optimize Transcription Settings:

   • In your Retell AI agent's transcription settings, select "Optimize for accuracy" option. This setting helps the model focus on precise word capture, especially for foreign languages.

   • Test prompts in the target language to ensure the agent processes inputs correctly without defaulting to English assumptions.

3. Choose the Right Multilingual Models:

   • Begin with the Turbo V2.5 model, which is faster and supports multilingual transcription effectively for most use cases.

   • If pronunciation or accuracy issues persist, switch to a dedicated multilingual model for deeper language handling.

   • Example for Spanish: Turbo V2.5 can transcribe casual conversations accurately, but for formal or technical Spanish (e.g., legal terms), the multilingual model may provide better results.

   • Example for German: For business calls involving numbers or addresses, start with Turbo V2.5 and monitor for improvements; escalate if compound words are fragmented.

4. Testing and Iteration:

   • Conduct tests in the foreign language environment, providing entire prompts and sample interactions in that language.

   • Loop in Retell AI's solutions engineering team for advanced assistance if standard optimizations don't resolve the issue.

   • Monitor for edge cases, such as mixed-language inputs (e.g., English emails in a French conversation).

Examples Across Different Languages

• French: If transcription misses accents or liaisons (e.g., "bonjour" pronounced incorrectly), use ElevenLabs' Camille voice and Turbo V2.5 for faster, accurate results. Test with prompts like "Transcrivez cette conversation en français" to ensure details like "email@exemple.fr" are captured.

• German: For issues with umlauts or long words (e.g., "Wirtschaftsprüfung"), select a German-specific voice and optimize for accuracy to avoid splitting compounds. Example test: Transcribe a call discussing "Telefonnummer: 012-345678".

• Spanish: Pronunciation errors in rolled 'r's or accents (e.g., "mañana") can be mitigated with voices like Mia. Use multilingual models for regional variations, such as transcribing "dirección de correo electrónico: ejemplo@correo.com" without loss.

• Other Languages (e.g., Portuguese, Italian): Apply similar steps—choose ElevenLabs voices for the language, start with Turbo V2.5, and test key phrases to build reliability.

Additional Tips

• Always verify improvements through repeated testing in real-world scenarios.

• If using multiple languages in one agent, specify language detection in prompts for seamless switching.

• For persistent problems, contact Retell AI support with specific examples, including language, model used, and error logs.

By implementing these strategies, you can enhance your Retell AI agent's handling of foreign languages, leading to more reliable, accurate transcription and interactions.