More people than ever are listening to podcasts, but as they soon find out, discovering new ones is a cumbersome process that lacks the serendipity users take for granted in other apps. CastBox wants to fix that by becoming “the YouTube of audio.” The podcast player for iOS and Android, which has raised $16 million in funding so far, is launching a new audio search feature today that uses natural language processing to let listeners search for keywords and topics across more than 50 million episodes.

Founder and chief executive officer Xiaoyu Wang wants CastBox’s in-audio search to make finding relevant sections of audio as easy as searching in text. The feature supports English, and Wang says the company wants to perfect it before expanding into other languages. CastBox’s funding includes a recently closed $12.8 million Series A round led by Qiming Venture Partners and IDG Capital, with participation from SIG China, GSR Ventures and ZhenFund.

With the addition of in-audio search, CastBox hopes to become the breakout podcast player for iOS and Android. It will start co-producing and releasing original content this quarter and its monetization plan includes a premium option with extra features.

CastBox is headquartered in Beijing, with offices in Hong Kong and San Francisco, and claims that its podcast player has been downloaded more than eight million times. Though most of CastBox’s users are English speakers, Wang says she decided to base the company in China because of the engineering talent there.

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Before founding CastBox in early 2016, Wang worked at Google in Japan and Dublin. She started tuning into podcasts to study Japanese and keep up with the news, but had trouble finding a player that supported different languages and gave personalized recommendations. Many were barely more than lists of podcast RSS feeds.

“I couldn’t find an app in multiple languages, so I had to download MP3s and organize them. It was complicated and like creating an audio black hole unless I remembered to listen to them,” she says.

To stand out from other podcast players for Android when it first launched, CastBox pitched its app to “podcast addicts” and then paid close attention to their feedback, adding new features quickly and resolving all issues within a day. As their early listeners began recommending CastBox to their friends or on their own podcasts, CastBox’s Android app started to gain traction. It then launched a version for iOS, but since Wang realized that it would be difficult to compete with iTunes, which many listeners already use as their default player, the startup decided to focus on refining its discovery features.

In addition to sorting podcasts by the usual parameters, like an episode’s release date, CastBox’s recommendation engine considers each user’s search history and their listening behavior, such as which episodes they listened to in their entirety and enjoyed enough to share on social media and which ones they closed out of quickly.

The startup will use its Series A funding on marketing, producing original content and hiring engineers.