SOFIA, Bulgaria — Because of a recent copyright dispute, Bulgarian National Radio, the public broadcaster for the country, has been limited to airing music recorded before 1946. And so far, their listeners seem to have no problem with it.

The station had a 20 percent increase in listenership in January, the first month in which the change was in effect, over December’s numbers, said Bulgarian National Radio’s chief, Alexander Velev. He cited an audience report conducted by the consumer research company Ipsos.

Bulgarian National Radio has only been playing old music — classical music, early-20th-century jazz and concert recordings of traditional folk music, drawn from the organization’s archives — since the beginning of the year.

Under European Union rules, copyright lasts for 70 years after a musician’s death.

The radio station says it was compelled to reduce its music offerings after Musicautor, an independent rights organization that controls distribution of millions of Bulgarian and foreign songs, suspended its contract with Bulgarian National Radio, after demanding a steep rise in fees, to 1.8 million leva (about $978,000) a year, from 500,000 leva (about $271,000).