Re: at least you won't hear people screaming
Um, if I'm not mistaken noise cancellation allows you to clearly hear people screaming.
If you want actual silence, what you need is more akin to industrial earmuffs - they cancel everything, to a point.
Edit : After checking the web site, I found that the app has a setting called Transparent Hearing. If that is activated, you can hear people talking to you. That means that, if it is not activated, you can't hear them. So your point stands, in the right conditions. Of course, if you're wearing these on a plane, I don't see why you would activate it.