Duolingo, a language learning app with over 500 million users, is working on a music app, TechCrunch has learned.

The Pittsburgh-based tech company currently has a small team working on a music product and is hiring a learning scientist who is an “expert in music education who combines both theoretical knowledge of relevant learning science research and hands-on teaching experience,” according to a job posting listed on Duolingo’s career page. The company also posted a job that was soliciting a freelance music composition and curricular consultant, but the company is no longer accepting applications for that position.

The job listing suggests that the app will teach basic concepts in music theory using popular songs and teachers.

Duolingo has slowly grown beyond language learning into several auxiliary new projects that may represent significant revenue streams in the years to come. For example, The Duolingo English Test, which spun out from a hackathon project in 2014, is an online certification exam that tests language proficiency. The company also launched Duolingo ABC during the pandemic, which is a free app focused on English literacy for kids ages 3 to 6.

In October 2022, the company announced Duolingo Math in its first subject expansion beyond its original roots of language learning and literacy. The math app is free and similar to language learning; both require methodical thinking and the ability to apply functions to get to answers.

Music is a subject that sits in the pedagogical middle of language, which requires nuance and context, and math, which requires focus on formulas to provide correct answers, or in this case, sounds.

Language, math and music in Duolingo all require users to know the basics. And that’s how Duolingo differentiates itself: It focuses on building blocks, instead of specific mastery, as a way to learn a skill.

Plus, it doesn’t hurt that there appears to be some executive buy-in to the concept overall: Duolingo chief business officer Bob Meese is an investor in Trala, a tech company that offers virtual violin lessons. It recently raised $8 million in its Series A.

So far, the broader purview appears to be resonating. Duolingo more than doubled its paid subscriber base last year, according to its last quarterly update. Total revenue also nearly doubled at $369.5 million for 2022.

It’s unclear how Duolingo’s music app will materialize over the next few months — for example, we don’t know whether the app will help people read music, write music, learn instruments, or all of the above — or if it’s just a tiny experiment within an organization known to love a test or 10. TechCrunch reached out to the company for further comment and will update if we hear back.

Duolingo is working on a music app by Natasha Mascarenhas originally published on TechCrunch