Recordings arrived on the American scene with the turn of the 20th century. At first, the sound emanating from the records or cylinders was woefully indistinct, but technology moved ahead quickly. By the mid-1910s, gramophones were an essential fixture of many well-appointed homes, occupying a place of honor next to the parlor piano, conveying performances with some degree of subtlety. It must have been thrilling for music lovers in Dallas or Duluth to hear the nation’s top musical performers right there at home on Main Street, one after another — Enrico Caruso, Al Jolson, Sousa’s band.

In the 1920s, the new medium of radio entered the soundscape. Record-company executives, judging it a serious competitor, sought ways to reinvigorate their product. This coincided with an important advance in recording technology that arrived in 1925, Western Electric’s introduction of an electrical recording method that markedly improved the fidelity of recordings, increased their sonic range, and allowed audio engineers to tweak the sound-gathering process to achieve specific musical results. It would define how records were made for the next two decades, until part of the process was replaced around 1945 by magnetic tape recording and the rest made obsolete by the digital revolution of the 1980s.

This week, PBS airs the initial installment of American Epic, a series of television documentaries (directed by Bernard MacMahon) that looks at the era of early electrical recordings. It focuses on the democratization of artists and repertoire that began at the same time. Before 1925, nearly all of the music that record companies issued was either classical (with a large infusion of opera), band repertoire (Americans loved their marches), or Tin Pan Alley songs (eked out by a helping of vaudeville routines). After 1925, however, recording companies showed a growing interest in the music one might hear far from the urban centers, and they sent scouts to corners of the country that up until then had been ignored by the men in business suits. American Epic is about the recording industry’s discovery of the nation’s folk music.

In the course of three episodes, the series traces the routes of recording pioneers who fanned out across the country to capture the music made by the common people, by farmers, miners, and housewives who sang the songs that meant something to their communities and did it well enough that people wanted to hear them. The first episode, “The Big Bang,” introduces us to producer Ralph Peer; armed with a somewhat portable recording machine, he headed for Tennessee, where he uncovered such musicians as the Carter Family and the Memphis Jug Band — basically laying the foundation for what would develop into commercial “country music” and “rhythm and blues.” The second installment, “Blood and Soil,” scours the American South, capturing the voices of Elder J.E. Burch, Charley Patton, and many others — the starting point for Delta blues and gospel.

The American Epic team carries out a great deal of detective work, sometimes starting from an obscure name on a record label and always from an arresting performance in the grooves. They uncover ancient newspaper articles inviting area musicians to gather for what might become recording sessions. They track down the very places where the musicians lived and where the records were made. They root out the descendants of those musicians along with their aged acquaintances. They assemble old photos and film sequences that bring the personalities alive for television. For some parts of the story, these archival materials are scarce indeed; especially in the first two episodes, which each runs 60 minutes, one senses a certain amount of padding along with a feeling of déjà-vu when the same visual material comes back for repeat visits. But even then, there is the music. American Epic keeps it front and center, allowing the recordings to play at length rather than reducing them to brief snippets.

The folk music of Appalachia and the American South is relatively well known today. The glimpses these programs afford of the impoverished environs in which this music grew — cotton fields, flooded farmlands, desolate outposts — will be affecting, if not entirely unfamiliar. But with the 90-minute third episode, “Out of the Many, One,” the series leaps to its highest level. The pace quickens as we make the rounds of numerous widely dispersed communities that less predictably include Joseph Kekuku and his Hawaiian guitar; Lydia Mendoza and her soulful Tejano ballads; the Breaux Family and legendary Cajun singer Joseph Falcon of Louisiana. Here, too, the Southwest gets its moment in the sun, thanks to a segment focusing on the Hopi Indian Chanters, whose two sides of a 1926 Victor platter offer performances of the “Chant of the Snake Dance” and the “Chant of the Eagle Dance.” The story behind this record, which proved to be a strong seller for the label, is fascinating: an Anglo named M.W. (Milo) Billingsley fell in love with the Hopi, was adopted by the tribe, and helped defend them when some nasty souls in government started branding their sacred ceremonies as blasphemous. A moving commentary is provided by Leigh Kuwanwisiwma, the present-day director of the Hopi Cultural Preservation Office. He conveys ineffable sadness in recounting how these Hopi ceremonies were saved by performing them in public before a hell-heeled and well-connected crowd on the steps of the Capitol in Washington, D.C. — “They may have borrowed from another, non-sensitive ceremony,” he allows — essentially sacrificing the privacy of these rituals in order to preserve them. It led to a resolution from Congress allowing the Hopi to practice this ceremony forever. I do not know if today’s Hopi will be happy about seeing this vintage film of the snake dance aired in a PBS series, but I assume the network exercised the proper courtesies before including it. It is a beautiful segment, and Kuwanwisiwma’s commentary proves enriching insight.

Most of the talking heads who help dissect these recordings are active musicians, including blues legend Taj Mahal (whose insights are simply terrific), roots rocker T Bone Burnett, hip-hopper Nas, and garage rocker Jack White. Burnett, White, and Robert Redford (who serves as narrator) are the series’ executive producers. In supporting publicity, White makes a striking observation: “In American Epic we can examine how important the fact is that when phonograph records were invented, for the first time ever, women, minorities, poor rural men, and even children were given the opportunity to say whatever they wanted in song, for the whole world to hear, shockingly without much censorship. What they were allowed to say on phonograph recordings, they were not allowed to speak in public or in person. That is an astounding thought.”

The interviewees bring various perspectives to bear, some more convincingly than others, but in every case their appreciation is unmistakable. In fact, many of them appear in The American Epic Sessions, a two-hour program and appendage to the series in which modern musicians recreate the recording experience of the 1920s. They perform some of these early songs to a reconstruction (by engineer Nicholas Bergh) of an electrical recording machine of the time. It is not as insistently captivating as the three installments of the series proper, but it is sure to delight fans of the participants (a diverse group that includes Willie Nelson, Elton John, and Los Lobos) and it does provide an unusually hands-on perspective on a potent chapter of America’s cultural history.

The three episodes of “American Epic” will be broadcast in New Mexico by KNME-TV (digital channel 5.1) at 8 p.m. on Tuesday, May 16, May 23, and May 30, with “The American Epic Sessions” following at 7 p.m. on June 6. A companion soundtrack, consisting of 100 songs on five CDs, is being released as a collaboration by Legacy Recordings, Columbia Records, and Third Man Records. The book “American Epic: The First Time America Heard Itself” is available from Touchstone.