Noise Canceling Earphone Question

pu1. I don't know if all the products are the same, but I've used the boss and Sony products, and they cancel the noise as soon as you turn on the earphones

2017-12-14

OK

pu2. It's true that it works with or without music, but if you don't, you can hear the outside sound quite well

2017-12-14

OK

pu3. When I think of noise cancelling products, there is no answer except for the boss, but I can feel the emotion when I first cancel the noise with the boss. After a while, noise cancellation doesn't work as well as I thought. Especially, I can't hear people well, but I can hear them making sounds. Don't expect too much

2017-12-14

OK