ELI5 Noise Canceling - why does it block low sounds better than high?

What is the difference between noise canceling and noise isolating headphones? Why aren't noise cancelling headphones as effective in cancelling high pitch sounds as they are in cancelling low pitch sounds? Can noise canceling headphones be harmful to your hearing?   ... We explain like i'm five!     Thank you to the r/explainlikeimfive community, and specifically the following reddit users whose questions and responses formed the basis of this conversation: skippy7890, bluefire009, viskerratio, van-nostrand-md, MG2R, umaijcp, jazztaprazzta, montebious, afcagroo, garyfirestorm   To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Send us an e-mail: [email protected]