From: http://www.wisegeek.com/what-is-a-good-bitrate-guideline-for-mp3-files.htm For audio voice recordings such as lectures or language lessons preserved in wave form, bitrates of 32 kilobits per second (kbps) should be acceptable, though 64kbps might provide better quality depending on the source. Voices might sound “flat” at 32kbps, though they will be understandable. A 64kbps MP3 file made from a voice […]