Okay but, i thought you would add this and explain it in layman terms.
http://en.wikipedia.org/wiki/MP3
Well I don't need to read that page to explain it in layman's terms.
It's an audio file format that compresses a song, on average 1 MB of data per minute, assuming the program that created the file used the standard 128k bitrate. (Lately 192 and 320k rates are common due to larger hard drives.)
So on an audio CD you can typically fit maybe 14 songs on, if you burn it as a data disk instead of an audio CD and put the music on in the form of MP3 files, on a regular 700 MB CD, if the average song length is 4 minutes, you can put 175 songs on there. A CD player capable of playing MP3 discs can potentially start at the beginning of the CD and keep playing for your entire 11 hour driving shift without playing the same song twice.
Because the files are compressed in a lossy format, some audio information is discarded in the compression/encoding process. The technology for creating MP3 files is designed to only eliminate audio frequencies that are considered to be inaudible to the average human ear.
The average person can only hear sounds ranging from 20 hz (subwoofer cone moving in & out 20 times per second) to 15,000 hz (tweeter cone moving in & out 15,000 times per second).
By eliminating frequencies outside of that range, and through other compression methods, they can knock the file size down significantly and very few people can tell the difference. You'd have to play a store-bought CD and then play the MP3 version immediately afterwards on a decent stereo without any ambient noise (like an idling engine) in order to tell the difference.
On songs where you have lots of different instruments playing simultaneously, you're more likely to hear the limitations of the MP3 format than if you were listening to a song with fewer instruments.
Example:
Champagne Supernova by Oasis.
(I can only provide the YouTube version & don't know what format it uses for audio)
At the 2 minute mark, the song gets noisy & there are too many audio sources mixed together & if you listen to it with headphones, at any volume at all it sounds distorted. The format simply can't reproduce that many sounds accurately. I wouldn't be surprised if the original studio recording even sounds distorted at that point.
