A compressed, proprietary, and generally copy-protected format used for audio book files sold by Audible.com. The higher the number of an Audible file, such as 2, 3, or 4, the better the quality.
Digital spoken word file, such as audiobooks and radio programs, with four compression rates (Audible 1, 2, 3, and 4). iPods are compatible with rates 2, 3, and 4. (Various sites let users download audiobooks, radio programs, and audio versions of newspapers and magazines.)
A digital file format for spoken word files purchased from the Audible.com website. Audible files are available at four compression rates — Audible 1, 2, 3, and 4 — with 4 being the least compressed and 1 being the most compressed. iPods are compatible with files encoded in Audible formats 2 through 4.