As a result of NM's recommendation I purchased a pair of Shure E3C and was more than impressed with the performance they provided and the noise it really did isolate. You receive various in-ear plugs so that you can obtain a good seal and after using the foam ones on a recent USA flight I have now found that one of the others provides a great seal also. I travelled in QF J Sky bed seat which has a three pin audio plug so you need an adapter for that, don't know about NZ. They block out considerable aircraft noise, including other pax talking but be warned as it was also difficult to hear the FA asking whether you want another drink.
Jands are the Australian importers of the Shure E3C. I had a bad experience when I purchased my first pair of E3C's on ebay, but Jands replaced them for me so must give them a rap.
Jands