Q: Have you or anyone generated a spreadsheet showing all the different iPod-compatible compression schemes and how big a song and CD would be with each scheme (using the same sample song and same sample CD) AND also how the song sounds (using high quality headphones)?

– Mike

A: For a good comparison of the various iPod bit-rates, sizes, and storage capacities, take a look at our iPod Storage Calculator, which provides a summary of the total number of tracks you can fit on a given iPod at the various possible bit-rates:

Sound quality, on the other hand, is a very subjective thing, and therefore difficult to quantify. It will depend on not only bit rate, but also the earphones you use, and in some cases, the iPod you’re listening to. Our recently published Complete Guide to Earphones provides some insight on the different sound quality and attributes of various earphones, but even then the quality of the music itself is going to vary from one person’s ears to another. Proper blind testing is an inconvenient but useful option for a person to truly determine what various compression levels and bitrates sound good enough for his or her own listening experience.