How would you define unnecessary noise? Conversely, what do you see as the necessary noise channels? How would you define and know when it is appropriate to open and close? (edit: added last question)
As for unneccesary noise example, that would be feedback of people whose feedback I do not value.
And as for edited and added last question - it depends. :)
Dilluting my karma like I just don't care! :)
Whatever your methodology is, at some point you can't parse more feedback, and it's then noise, whatever its contribution is.