When the late folklorist Alan Lomax began searching for the proper acoustics in which to record musician Fred McDowell’s work, he checked everywhere: the kitchen, the bedroom, even the bathroom of the artist’s Como, Miss., home.

After four days, Lomax settled on the front porch, and the result is a 1959 recording that features McDowell’s music with a distinctive twist: the sound of chirping crickets.

In retelling the anecdote Wednesday during a formal announcement of the Library of Congress’ acquisition of the Alan Lomax Collection, Librarian James Billington noted that the McDowell recording is indicative of the unique quality of the works Lomax amassed during a 70-year period.

“There’s so many happy surprises in this collection,” Billington said. The collection, which includes more than 5,000 hours of sound recordings as well as photographs, film, video, books, correspondence, scholarly books and journals, was previously housed at New York’s Hunter College, where Lomax founded the Association for Cultural Equity.

Lomax, the one-time head of the Library’s Archive of American Folk Song, traveled widely — to the American South, Caribbean, Britain, Scotland, Ireland, Spain and Italy — to record and collect traditional singers, instrumentalists and storytellers. Billington said Lomax is considered “a pioneer and a hero” in ethnographic documentation.

Mickey Hart, the Grateful Dead’s longtime drummer, described Lomax’s collection — which includes recordings by Huddie “Lead Belly” Ledbetter, McKinley “Muddy Waters” Morganfield and David “Honeyboy” Edwards — as “an oral snapshot.”

“It covers so much ground,” said Hart, a board member of the American Folklife Center. “He was a man of his time.”

In addition to his work as a folklorist, Lomax was the author of several books, including the “American Ballads and Folk Songs” and “Our Singing Country,” published in 1934 and 1941, respectively. Lomax also worked as a radio broadcaster, filmmaker, concert and record producer, and host of the PBS television series “American Patchwork.”

Lomax began his career in 1933 at the age of 18, with his father, John Lomax, gathering folksongs for the Library’s collection.