I was looking for a solution to listening to my MP3 player or DVD player on a commercial airplane. Ear buds are useless and noise-canceling headphones are uncomfortable (I wear glasses). Amplification of the signal to overcome the aircraft's noise could be dangerous. The ER-6's seemed to be a reasonable solution and were more in my price range than the ER-4's.I have been very pleased with their performance. The sound isolation is excellent. particularly with the foam ear tips. There is some contact sound transmitted through the cables when I move, but that is not much of an issue on a plane. Sound reproduction is excellent and they can also be used with the airplane's in-flight entertainment system.