Noise cancelling vs. noise isolating
Active Noise Cancellation
To provide Active Noise Cancellation, internal and external microphones measure unwanted ambient noises, then circuity in the headphones generates sound at a frequency that cancels out those noises. Active Noise Cancellation works whenever headphones with this feature are turned on.
Adaptive Noise Cancellation is a type of heightened noise cancellation. When you're listening to music, speaker output strikes a balance between audio quality and noise cancellation. When you're not listening to music, the level of noise cancellation automatically increases to block outside sounds.
Passive noise isolation
Noise isolating earphones and headphones passively block out ambient sound without batteries. Adjustable-fit eartips on earphones and extra ear-cup padding on headphones act as physical barriers to keep unwanted noise from reaching your ears. These barriers also help prevent people around you from hearing your music.