With Pandora dominating and Apple looming, Songza is adding listeners and introducing features that change the way people use Internet radio. The service had 4.7 million active users in March, up from 2 million active monthly users at the end of the summer, and has served over 560 million songs in the last 30 days. The service is far behind Pandora’s 70 million active users but has proven to be a formidable competitor.

The New York City-based company, which recently raised $3.8 million in fresh funding, has been able to gain listeners in a tough marketplace. The company says its users spend a total of 65 million minutes with the service each day. CEO Elias Roman tells Billboard daily usage was in “the teens of millions” of minutes last summer and has risen 50% since December.

New features add to a service that has been a creative departure from typical Internet radio services. “[Version 3.0 is] prettier, it’s more powerful and it’s easier to use,” says Roman. The new app is available only for Apple iOS devices. iOS accounts for most of the Songza app’s installations, says Roman.

Some of the new features simplify the user experience and makes it easier to find music. For example, by holding down any button on Concierge will immediately play a playlist that Songza thinks is the best suited for the listener at that moment. Another way to quickly get a playlist is to shake the device — which brings up a search field — and let Songza know what activity you’re engaged in. For example, Songza will bring up playlists built for parties if a listener enters “Entertaining.”

Research told the company that people wanted to be Songza power users and learn about everything to use. Roman likes the idea of having “an ongoing dialogue” with users rather than forcing a tutorial on users. So Songza created “coach marks,” or in-app tips that enhance the user experience. One of the first coach marks to be deployed predicts the user’s level of boredom in order to fight what Songza calls “stale music syndrome.” If a person is skipping songs often or listens to a particular playlist repeatedly, the coach mark will suggest new music so a person “can very easily expand their horizon.”

Another new feature is high-quality audio via a partnership with Audyssey Laboratories, a Los Angeles-based company that creates audio technology products for mobile devices, home theater systems, speaker systems and cars. The technology improves headphone sound quality without increasing data usage of Songza. Over 100 different headphone models will be covered. [billboard.biz]