Creative Commons Audio Assets
When someone gives their creative work a Creative Commons license, it means they are giving permission to other people to copy, share, and/or adapt their creative work in some circumstances. To learn more about the different types of Creative Commons licenses available, visit Creative Commons Licenses. If you want to use audio with a Creative Commons license in a media project, make sure that it has a license that 'allows derivatives', and also make sure to give attribution to the author in your credits.
Here are some useful sites for finding Creative Commons licensed audio:
CC Mixter offers a range of music with Creative Commons licenses, including spoken word. The site offers a beta search tool, dig.ccmixter, to help people find 'fantastic, liberally licensed music' to use in podcasts, videos, games, and more.
The Freesound Project is a huge, collaborative database of sounds (e.g. audio snippets, samples, recordings, bleeps... but not music), released under the Creative Commons Sampling Plus license.
SoundBible.com provides an encyclopedia of royalty free sound effects and sound clips that can be reused and adapted. All of the sounds on the site have a Creative Commons Attribution 3.0 license or are in the public domain.
SoundTransit is a collaborative, online community dedicated to field recording and phonography. All sounds on the website have a Creative Commons Attribution 2.0 license.
The Internet Archive Audio Archive collection has over 200,000 audio items that range from alternative news programming, to Grateful Dead concerts, to Old Time Radio shows, to book and poetry recordings, to original music contributed by users. Licenses in the collection vary.
Creative Commons Audio Content Directory lists many other websites that contain audio with Creative Commons licenses.