In my opinion it is a scam, a fraud, noisecancelling only works if it is centered on one point. You will need to have the microphone exactly where you wanna cancel the sound, and the wave that cancels out the sound needs to be adjusted to have correct amplitude and frequency at that point.
This works okay with headphones because the space is very limited. It's still not perfect though, because the microphone is not exactly where your ears are. It works fairly well though with additional adjustments. You can't however silence a room because the wave is different depending on your location.
You might be able to silence, or slightly lower volume at one point, or if you have perfectly symmetric room with perfectly placed speakers playing reverse phase sinewaves it might be possible too silence each. However, you being in the room would disturb the waves and create noise again.