After clicking the Device link in the Audio dialog box, the Audio Settings dialog box will open. This is where you have to make an important decision about your bitrate.
You have two choices in the Bitrate drop-down menu: Constant and Variable. Constant Bitrates (CBRs) produce smaller file sizes. By contrast, Variable Bitrates (VBRs) tend to produce audio with a higher, more consistent quality level than CBRs, but the VBR file sizes will be larger than CBRs. For that reason, most Captivate developers stick with Constant Bitrate.
Then you have to select from one of the four bitrate settings: CD, Near CD, Custom or FM. So many decisions... so little time. Bitrate is defined as the number of bits that are conveyed or processed per unit of time. Using a higher bitrate setting, such as CD Bitrate (128 kbps), will result in higher quality audio but a larger published lesson.
If you decide to use a higher quality bitrate than FM Bitrate, you should spend time experimenting with the options to see which selection sounds best to you. As a general rule, the FM Bitrate is more than adequate for eLearning audio that will be played through typical computer speakers or headsets.