ive lived behind train lines for most of my time in Chicago. while you do get used to it after a while, i dont think theres any reason to romanticize noise pollution and any solution to ameliorate it is a positive. all sorts of long term health issues have been linked to it as well
http://www.sciencedirect.com/science...4067361361613X
the brown line is pure hell, esp in the summer when windows are open. i was right at the entrance to the tunnel for the red line as well, so i would get trains every 30 seconds. the earthshattering "bang bang!" of the first brown line run of the morning at 4AM would wake me up without fail every time. also was completely impossible to even have a conversation outside. the steel supports are extremely loud. i only did 1 year there but it was enough.
i now live along the red line further north (concrete embankments) and the sound issue is vastly improved, though windows open in the summer is still not great. but without question the concrete is more livable than steel.
to those speaking about noise machines, i use one and love it, but the reason it works is because it provides a constant mask and creates a new baseline. sounds that start and stop, or have peaks and valleys (as a train passing would, or even music for that matter) dont really achieve the same effect and bring your brain back to alertness.
i think theres a bit of stockholm syndrome with anyone who would say that a quieter train line wouldn't be a net positive. it should be quite obvious why any public policy decision should be favoring quieter environmental noise rather than louder.