The National Recording Registry is a list of sound recordings deemed "culturally, historically or aesthetically significant" by the Library of Congress. These recording are not necessarily selected as the “best” recordings of all time, but rather as works of enduring importance to American culture and, hence, in need of permanent preservation by either the Library of Congress or another qualified institution. The Librarian of Congress makes the annual selections to the Registry after reviewing hundreds of titles nominated by the public and after conferring with the Library’s curators and the distinguished members of the National Recording Preservation Board. Twenty-five recordings are named to the Registry each year.

The American Folklife Center has extensive audiovisual, manuscript, and photograph collections related to many aspects of folk life and culture, including field recordings of folk music dating back to the earliest days of recorded sound. The traditional arts, music, and oral histories of many parts of the world are preserved and archived within the AFC's collections, a portion of which are available online.

The American Archive of Public Broadcasting is a collaborative project between the Library and Boston radio station WGBH to preserve public media and digitize 40,000 hours of programs selected by more than 100 public broadcasting stations throughout the nation. Dating from the 1940s to the 21st century, these programs are available at the Recorded Sound and Moving Image Research Centers, at the WGBH Media Library and Archives, and online at this link.

The Studs Terkel Radio Archive is the result of a partnership between the WFMT Radio Network, the Chicago History Museum, and the Library of Congress. Terkel, a radio personality, author, and oral historian, interviewed people on topics ranging from Civil Rights, activism, war, and education, to film, music, theater, travel, journalism and much more. Thousands of hours of recordings of Terkel’s radio program at WFMT in Chicago, recorded between 1953 and 1997, are currently undergoing digitization by the Library. They are available in the Recorded Sound Research Center and in the online archive.

The Internet Archive, a digital library of internet sites, provides researchers, historians, scholars, the print disabled, and the general public with free access to a variety of materials and digital collections. The site includes an audio archive of streaming concerts, musical recordings, radio broadcasts along with literature and poetry readings.

American Rhetoric is a site dedicated to public rhetoric. It contains political, social, and religious speeches, movie speeches, resources related to the study of rhetoric, and exercises in rhetoric. The Online Speech Bank is a searchable database and index that contains streaming audio and the text of hundreds of important American speeches.

The Oyez Project, a free law project from Cornell’s Legal Information Institute (LII), the Chicago-Kent College of Law, and Justia.com, is a multimedia archive devoted to the Supreme Court of the United States and its work. It aims to be a complete and authoritative source for all audio recorded in the Court since the installation of a recording system in October 1955.

The Cylinder Preservation and Digitization Project at the University of California, Santa Barbara, has created a digital collection of over 10,000 cylinder recordings from the late 19th and early 20th century. Recordings can be downloaded or streamed online for free.

First Sounds is a collaborative effort by audio historians, recording engineers, curators and scientists to identify and make available the earliest recordings ever made. These recordings include a recording made by a phonautograph in 1860, nearly twenty years before Edison began experimenting with recording sounds.

FindSounds searches the web for sound effects that are freely available.

The G. Robert Vincent Voice Library at Michigan State University is a collection of thousands of hours of spoken word recordings dating back to 1888. Many recordings in the public domain are available for listening online.