What is Noise cancelling?

Active noise cancelling uses microphones and processing to cut steady background noise such as engines, air conditioning and office hum. It helps most on trains and planes, and less against voices. Every brand checked here offers it: Adorama, AGM Mobile, Ahifi CZ/SK/HU, MPOW and Audio-Technica all do. That makes the decision about seal, battery life and price instead of the feature itself.