Plants are good for slowing wind and filtering out some of the dust blowing in the air, but they are not a dramatic reducer of noise. It takes a very thick (perhaps a hundred feet thick) section of dense foliage to significantly reduce noise levels. This is why urban planners often use solid walls which are less aesthetic, but much more effective to deflect noise along highways in residential areas.
I don't mean to discourage you from planting a barrier wall as there are other beneficial effects and it would help a little on noise, but I just don't want you to have too high of an expectation of its ability to stop sound.
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