“Artists and labels can identify music that is a priority for them, and our system will add that signal to the algorithm that determines personalised listening sessions,” the company said. “This allows our algorithms to account for what’s important to the artist – perhaps a song they are particularly excited about, an album anniversary they are celebrating, a viral cultural moment they are experiencing, or other factors they care about.”

But the algorithmic juice comes at a price. “To ensure the tool is accessible to artists at any stage of their careers, it will not require any upfront budget,” Spotify says. “Instead, labels or rights holders agree to be paid a promotional recording royalty rate for streams in personalised listening sessions where we provided this service.” The new terms sparked an immediate backlash among recording artists. “This a form of payola or sponsored social media post. It is not necessarily illegal but the tracks would need to be labelled,” said David C Lowery, the singer-songwriter of Camper Van Beethoven, and a regular campaigner for musicians’ rights, referring to the 1950s scandal of DJs being paid to play particular songs.

Spotify’s push comes just a week after the company was presented with a campaign from the American Union of Musicians and Allied Workers calling for the company to guarantee a minimum payment of 1c per stream, and to “reveal existing payola, then end it altogether”. “Spotify encourages labels and management companies to pay for plays on the platform. In many cases, the artists do not even know this is happening,” the union wrote in an open letter to the company.

“Spotify should not be in the business of selling artists access to their own fan base. Spotify must publicly reveal where existing payola is occurring, and then stop systems of paid access that make an already unequal platform even more imbalanced.” The letter has been signed by 16,000 artists so far, Umaw says. Spotify has been contacted for comment.