Swedish music streaming service Spotify is set to announce a new feature that will allow users to pick music tracks and listen to them on mobile devices for free. That's according to a Thursday report from the Wall Street Journal.

The service is expected to be officially announced at an event in New York on Wednesday.

The report went further, adding that users will be able to pick tracks and put them in a playlist. If the playlist is long enough, Spotify will shuffle the songs and play them back a limited number of times, interspersed with ads. If there are not enough songs in the selection, Spotify will fill in the gaps with other songs.

Currently, Spotify offers free mobile listening of randomized songs along genres in the U.S. but doesn't allow users to pick specific tracks without paying.

A current Spotify premium subscription, which costs $10 a month in the U.S., allows users to listen to any songs or albums they choose, without ads. The premium plan also allows users to save music to their mobile devices.