Based on your search query, I would recommend ElevenLabs. This tool leverages voice AI to create or clone voices that can speak in up to 30 languages. This feature can be particularly useful in making lessons more interactive and catering to different learning needs.

Here are some key features of ElevenLabs that could be beneficial:

• Voice Creation: This feature allows you to build synthetic voices from scratch by selecting gender, age, and accent. You can create a custom voice that fits your teaching style for educational videos.
• Speech Synthesis: This feature uses the voices you made to produce final audio outputs. You can turn written lessons into spoken words, making your content more accessible to students.
• 30 Language Support: The voices retain their characteristics across languages. This can help in teaching languages with a consistent voice, aiding in better understanding.

ElevenLabs offers a free plan with 10,000 characters per month, which is good for short interactive lessons. If you need more, there are paid plans starting at $5/month for 30,000 characters and a commercial license. This could be useful if you're creating more content.

Please note that some users have reported issues with the pronunciation of specific words, and non-English voices may have lesser quality as they are still in the "experimental" phase. However, many users appreciate the lifelike voice quality and its utility for language pronunciation.