OK, I’ve tried a zillion headphones. From Shures to JVC to everything highly reviewed. I’m still back to the Etymotic ER-4P. Lost these on the plane and got them back. Main reason besides the amazing sound is that they really fit. The Shures are a semi-isolating. You get 10dB of silencing. The ER-4P really fit my big old ears and give you an amazing 35-42dB with foam tips. It is like wearing earplugs. Perfect for being on a plane or tuning out the world. BTW, the big difference between the ER-4S and the ER-4P is that the ER-P has lower impedence of 27 ohms so can be directly driven by an iPhone or iPod. The ER-4S is 100 ohms and is flatter but needs a headphone amp to really sound good. OTOH the ER-4S has been compared with $20,000 speakers.
There is a great technical discussion of both noise isolation and frequency response. The main point is that most sound recordings are equalized so they sound OK with typical speakers in a typical room. Basically speakers that are flat in a sound chamer, when they are put in a room show 4-10dB down at 10kHz. The high frequencies are rolled off which is what the ER-4S does. This sounds flat to a normal human. Interesting huh?
Amazon by the way carries these things for about $180.