A technical reason for this could be the action (the distance from the fretboard to the underside of the strings) needs to be measured and adjusted. This done via adjusting the trussrod and the bridge. This can be done yourself, but some prefer to be safer than sorry by asking a professional guitar tech to set-up their guitars.

But when you say "background noise," do you mean a type of buzzing? Also, which type of strings and guitar do you have?