We've just had triple glazing fitted as our house is quite near the railway line and the difference in sound levels is unbelievable, I think the energy savings are supposed to be really good as well. - we'll see when we get our next heating bill!
In one of our old houses, we lived next door to an airfield with jets taking off at all hours (my dad is in the RAF). We had single glazing where you normally have a window, and then another layer of glazing on the inside of the window sill (parallel with the inside wall of the house IYKWIM). Worked brilliantly in the winter (when the windows were shut!).
We have ishoooos with clocktower bells which chime all night (clock belongs to local council so we are going through channels with them to try and resolve but not looking too hopeful). Alternative solution is to beef up glazing.
Does anyone know whether triple glazing is more effective sound proofing than double glazing with 28mm external glass?