Noise isolating earbuds.
On my way to the last ski holiday I bought a cheapie pair of noise canceling earbuds at the channel tunnel shop, so I could listen to music in the car without needing the volume high to overcome the noise. It certainly made listening easier, but the tonal quality of the music changed when the active canceling was switched on, and only the low frequency noise was reduced significantly. Yes, that is the worst of it, but it whetted my appetite for something better.
After searching the net for a good pair of noise canceling earphones, I found the Shure website and tried their flash-player demo of the amount of sound reduction expected from noise canceling and noise isolating 'phones.
Shure claim a much better sound reduction for the sound isolating ones, so with some trepidation about spending significant amounts money on something that would not live up to expectations, I ordered a set of Shure E3C 'phones from Advanced MP3 Players
They are good, if rather expensive. muninnhuginn, who is also interested in good sound, and wants to be able to hear it over the sounds of the city, tried them out and may be tempted... Well worth considering for people who like to listen to music and would like hear it over the noise while traveling.