When you look at purchasing headphones most will want to use them to place phone calls and receive calls from others. Many times when people speak about noise cancelling they are speaking about the headphone side and not the microphone portion.
Are AfterShokz noise cancelling? While bone conduction headphones can't be noise cancelling since they don't cover the ears, the microphone does have active noise cancelling to ensure your voice is picked up over crowd noises. This works very well even in crowded and noisy environments to help you.
When you use bone conduction headphones you will have to adjust to hearing from both the open ear sounds from the surroundings but the hearing from your bone vibrations which can take a little bit to adjust to.
Once you are past this initial oddness you will find that it comes pretty easy to listen and speak naturally.
The AfterShokz brand wireless models (Aeropex, Air, Titanium) are all equipped with dual noise canceling microphones for making and taking phone calls when paired with a smartphone or other Bluetooth-enabled device.
If you are in a loud environment this means the person you are speaking to will be able to hear you over the other crowd noise within reason.
I would not suggest purchasing them for the noise cancelling alone as you can get a set of in-ear headphones that will also feature noise cancelling. I would suggest researching bone conduction technology more before making your choice if you haven't read much about them before.
Looking for the Best Bone Conduction Headphones, check out our Buyers Guide over here where we review what you need to know about your headphones prior to making your buying decision.