I own a set of QC35's also a pair of 700's the noise cancelling works for a shirt time then when it stops working it just amplifies the sounds around you. I'm starting to wonder if Bose just advertises noise cancelling tech. I haven't actually had a set of noise cancelling headphones from Bose that works properly to begin with. The first pair I bought was on Amazon they stopped working. Then I bought my QC's from Bose then they stopped working. Then I bought a pair of 700's direct from Bose. Now they stopped working. Everytime a pair of them stop working all they do is amplify the sound around you.