If it seems like you are listening to music more but enjoying it less, some people in the recording industry say they know why. They blame that iPod that you can't live without, along with all the compressed MP3 music files you've loaded on it.

Those who work behind-the-mic in the music industry -- producers, engineers, mixers and the like -- say they increasingly assume their recordings will be heard as MP3s on an iPod music player. That combination is thus becoming the "reference platform" used as a test of how a track should...