I know noise canceling headphones do block out a bit of it but is that because of the noise canceling system or ear just being covered blocks it out. And I’m planning on buying Panasonic RP-HC500.

Noise cancelling headphones will block out most but not all outside noise by using a small microphone to pick it up and a small amplifier and some processing circuitry to create an inverted version of the noise that is then used to cancel the noise that reaches your ears by other paths. It’s like adding a positive number to a negative number in mathematics. When two sounds are equal but precisely opposite in pressure, the result is zero. Headphones that mechanically block as much unwanted outside sound as possible will have less noise that will need cancelling by electronic means.

Some brands and models come closer to the theoretical ideal than others. As with any headphone, it’s best to try before you buy. Flipping the switch on most models can be almost eerie to hear (or not hear).

Don