I get good sound isolation from hf5s: http://www.etymotic.com/ephp/hf5.html -- they are basically ear plugs with the ability to pump in audio. They work well enough to quiet (but not silence) a room/environment/train without audio hooked up.

The other extreme is to just use shooting range ear protection: http://www.earplugstore.com/hunting-and-shooting-ear-plugs.h... (or amazon'd: http://www.amazon.com/Best-Sellers-Sports-Outdoors-Hunting-E...)