It is unfortunate that this article perpetuates a common misconception that a single row of bushes or trees will have any beneficial acoustical effect. It's just not so; they will not "soundproof your yard". In order for vegetation to provide any measurable sound attenuation, the vegetative buffer must be several dozen feet thick, at the least. This is documented in the International Standard ISO-9613 "Acoustics - Attenuation of sound during propagation outdoors," which is the basis for all serious acoustical modeling outdoors. Trees may provide some minor psychological benefit by obscuring the sound source, but even that is not certain. In a paper published some years ago in the Journal of the Acoustical Society of America, some people were actually more annoyed by the noise after putting up a row of trees. After going to the effort and expense, the sound level didn't change to match their heightened expectations. A solid wall is a much better solution to problematic noise levels (so long as it breaks the line of sight between the source and receptor, including second floor bedroom window) as are better quality windows. Neither, however, is as pretty as some nice landscaping. Eric Zwerling, Director - Rutgers University Noise Technical Assistance Center.