After months of anticipation, the rumors about what exactly Rihanna was listening to in those $9,000 headphones can be put to bed: Sources tell Billboard that her Anti album will finally arrive this week, likely as a surprise release before Friday.

The album, the singer's eighth, has been pushed back repeatedly as she searched for a single to follow up last April's "American Oxygen," with sources saying the full project was initially planned for last May or June. Since then, rumored release dates in September, November and December came and went without an album as she continued to finalize the release, while the record-breaking sales of Adele's 25, released Nov. 20, pushed the timetable to January in order to vie for a No. 1 debut on the charts, according to one source.

Complicating matters has been Rihanna's $25 million deal with Samsung for the company to sponsor her album rollout and upcoming tour. After rumors of the deal first emerged at the end October, Rihanna tweeted a link Nov. 19 to the Samsung-powered website AntiDiary.com, which led fans to a mobile app in which they could explore a series of locked rooms. Since then, she has released seven promotional videos as rooms within the app unlocked, with the eighth room set to contain the album itself. But the final video still hasn't arrived, and after initially sticking to a semi-weekly schedule, the pace of releases slowed, with the latest video posted to YouTube three weeks ago on Jan. 4.

Those repeated delays made Samsung anxious, a source says. As the scheduled start of her world tour on Feb. 26 drew closer, there were concerns she might cancel or postpone the opening dates in order to stay in the studio and finish the album, or whether she would scrap the entire project and start over from scratch.

Now with the album on the way within days, the focus for most will shift to what the album will actually sound like and who will be involved. After gifting the Billboard Hot 100 with three singles in 2015 -- “Bitch Better Have My Money” (which peaked at No. 15), “American Oxygen” (No. 78) and the Kanye West and Paul McCartney-assisted “FourFiveSeconds” (No. 4) -- the pop icon has kept a low musical profile. One source tells Billboard that the album is more diverse than her prior releases, with a wide array of styles that move the overall product away from "BBHMM" territory. Sia has spoken repeatedly in interviews about working with Rihanna and last month released her single "Cheap Thrills," which she said was initially written for Rih. And earlier this month, reports surfaced that Rihanna shot a video in Los Angeles with Drake for a song called "Work." A source tells Billboard that Rihanna's next single, featuring an OVO artist, is set to arrive at 8 a.m. Wednesday.

One detail still to be revealed is how involved, if at all, Tidal will be in Anti's rollout. In November, rumors began to circulate that Anti would arrive exclusively on Tidal for its first week before being distributed wide to retail, which could have severely affected her first-week sales and kept her from debuting atop the Billboard 200. Rihanna debuted "American Oxygen" exclusively on the service in April, and the singer was one of 16 artists included in Tidal's launch last March, with a reported 3 percent stake in the company.

How she handles Spotify could also be of note, especially after recent high-profile albums like Adele's 25 and Coldplay's A Head Full of Dreams were kept off the service either for the first week after release or withheld from streaming services entirely.

Now that Anti is finally imminent, it will end the longest wait between albums of Rihanna's entire career; her last LP Unapologetic arrived in November 2012.

Billboard has reached out for comment to Rihanna's reps.