One thing... willow is deciduous, so there will be no leaves in winter, and hence less road noise damping. Laurel is evergreen.
Other traditional options are beech and hornbeam. Both deciduous, but if the hedge is close cropped every summer, the leaves will stay on through the winter - especially as yours is protected by a fence.
One other point - laurel is poisonous to livestock, although it doesnt sound as though thats an issue in this location.
We wont mention the other evergreen hedging plant which begins with l ...
Edited to add.... Ooh, but if livestock isnt an issue, what about yew? Slower growing but evergreen, pretty berries, lots of surface area...