Musopen is a non-profit focused on increasing access to music by providing recordings to the public for free, without copyright restrictions. Search by composer, musician, time period, or genre. Click on any item to listen, download, and view copyright license:
The Audio Archive, a branch of the Internet Archives, provides access to audio recordings in the public domain or under Creative Commons licenses. Collections include old radio programs and news broadcasts, book or poetry readings, and historical as well as contemporary music recordings. It also includes early film clips, including news reports and related images. Search by keyword, and be sure to utilize the suggested topics listed in the column on the right side. Look for the "Usage" statement on each item: 
The University of Houston's Digital History website contains a collection of historical music that is in the public domain (available for your use without permission from copyright holders). The collection is organized loosely into genres or time periods, including 1920s, Blues, Civil War, Irish, Jazz, Patriotic, WWI, and others.
LibriVox provides access to free audiobooks, that are in the public domain, and recorded by volunteers around the world. Users can listen to, or download, individual chapters or an entire book. Browse or search by book author, title, genre, or language.
The Free Music Archive is an interactive library of high-quality, legal audio downloads. You can browse works by creator or genre, and each item includes a clearly identified Creative Commons license as well as a link to contact the creator.
The Library of Congress provides access to music, interviews, field recordings, and other historic sound recordings. Collections include "Voices from the Days of Slavery", "Ragtime", "African-American Band Music", "Interviews Following the Attack on Pearl Harbor", and more. Be sure to look for copyright statements or rights statements for each item you select to use.
Europeana Sounds is an online collection of audio recordings from 18 different institutions located in 12 European countries. The audio recordings include music, but also spoken word recordings, environment recordings, sound effects, and radio programs.
Search for recordings by keyword, and limit your results by keyword, duration, country of origin, or usage:
Be sure to review the copyright statement that is included with each item.
Library Twitter
Library YouTube
Library Instagram