The recordings are not likely to appeal to casual music lovers, as even the engineer, Ward Marston of Marston Records, concedes. The surface noise is heavy, the music sometimes barely audible. “It’s not what you call pleasant to listen to,” said Mr. Marston, who is considered one of the leading audio-conservation engineers.

Still, the cylinders have obvious musical value, at least for specialist listeners. Runs, singing melodies, expressive rhythmic quirks can be picked out like gemstones from gravel. Ghosts come alive, and the listener mingles with them.

The recordings are also fascinating historical documents. They were mostly made in living rooms, at informal social occasions. Listeners applaud and yell “bravo!” The musicians often introduce themselves, as an 11-year-old Heifetz does in a high-pitched voice.

“Considering when they were done and the people that Block contacted, they are extremely exciting,” said Raymond R. Wile, a retired Queens College librarian who has written extensively about the early phonograph industry, including the Block cylinders. “I never thought they would surface.”

Edison invented the phonograph in 1877 and began developing it about a decade later, considering the machine mainly a device for business. It generally worked like this: a speaking tube would transmit the sound to a vibrating membrane, which would guide a needle as it incised grooves on a four-inch wax cylinder.

Image John A. Maltese and his father, John Maltese, co-producers of the CDs. Credit... David Walter Banks for The New York Times

Commercial recording did not begin until roughly 1889, but Edison’s agents and others recorded hundreds of cylinders before then. Only a handful of classical music recordings from the phonograph’s first decades survive. The earliest example is believed to be from July 5, 1888: excerpts of Handel’s “Israel in Egypt” incised at London’s Crystal Palace. Others include barely audible recordings of Brahms playing and speaking in 1889, and of a Danish bass, Peter Schram, possibly from the same year. A music buff in New York, Gianni Bettini, made cylinder recordings of singers in the late 1890s, but only several dozen survive, Mr. Marston said.