Recommend the Elacin product from personal experience.
In the 400 you put them in your ear in the climb and don't touch the volume's because the other person has the volume up so loud anyway to get over the wind noise. Some guys love the high speed climb (350knots), the noise is unbearable without plugs.
Ron and Edna
Here at CX, because they know better than the rest of the world. We remove the headset of the noise cancelling variety above F150. Why , "we didn't wear headsets on the tristar in the cruise"
Most of the 400 fleet only has normal headsets ie no inherent hearing protection either passive or active.
Buy the Elacin, you can get them in HKG. You'll thank yourself at your next medical.