Active Noise Cancelling

I am wearing noise-cancelling headphones right now. Maybe you own some too, they seem pretty popular nowadays. But why? What noise are we cancelling? We made and required noise-cancelling headphones because we created a world with too much noise. Rather than change the world to be quieter, we find it more palatable to filter out the pollution we introduced. Machines are omnipresent and we filter it with our headphones, but leave our pollution in the air and waves for animals to suffer.