Until now, the only available recording from Wangemann’s European trip has been a well-known and well-worn cylinder of Brahms playing an excerpt from his first Hungarian Dance. That recording is so damaged “that many listeners can scarcely discern the sound of a piano, which has in turn tarnished the reputations of both Wangemann and the Edison phonograph of the late 1880s,” Dr. Feaster said. “These newly unearthed examples vindicate both.”

In October 1889 Wangemann and his wife visited the 74-year-old Bismarck, then chancellor of the German empire, at his castle in Friedrichsruh. Bismarck listened to recordings made in Paris and Berlin, and at his wife’s urging, he made his own. He recited snippets of poetry and songs in English, Latin, French and German. Perhaps surprisingly, given his involvement in the Franco-Prussian War, he chose to recite lines from the French national anthem.

“Bismarck was a very, very witty man” and reciting the Marseillaise “would tickle him,” said Jonathan Steinberg, a historian at the University of Pennsylvania and the author of the new biography “Bismarck: A Life.”

Bismarck ends the recording with some advice, apparently for his son Herbert, who heard the recording a few weeks later in Budapest, to live life in moderation. “Bismarck was a gigantic man with gigantic appetites and a gigantic temper,” Dr. Steinberg said. “He never did anything in moderation, and Herbert was just as immoderate.”

Mr. Puille, the sound historian in Berlin, said it was not easy to identify Bismarck’s voice. But after he deciphered a reference to Friedrichsruh, Bismarck’s estate, in the announcement of one of the cylinders, “I immediately knew that I was on the right track,” he continued in an e-mail message.