I`m gonna sound backwards,but i`m scared of noise cancellng devices.
I just don`t think thier good for the ears.
using sound to cancel sound doesn`t ring all that healthy to me.
I think it`s gonna make people go deaf .
see I am a old folgy
You just need a better breifing on how it works.
A positive wave plus a negative wave = nothing.
Putting the noise 180 out of phase with itself destroys it.
Imagine a set of walls set across a feild from you .
Every other one is set a half wavelength further back than the front row so that they form a twin row staggered in frount of you.
Like this-_-_-_-_-_-_-_-_-_-_-_-_-_
You would only get a very weak echo because the echo of the second rank would be 180 out of phase with the echo of the frount. If the frount row were laid down the strong echo would reappear.
This would have to be calculated to match the main frequency of your voice someone with a voice several octaves diffrent would not see this effect unless the separation of the walls was adjusted to destroy his echo.
There is a bank of steps on a pyramid in Mexico that seems to sound like twittering birds , it is actually an example of the opposite of this effect the spaceing of the steps reinforces a particular set of frequencys by being about a quarter wavelength deep , it selectively returns a strong echo at this frequency with the rest of the sounds not amplified so much.
Oh and if you find a large corrigated culvert make a loud sharp noise in frount of it , the weirdness of a long tapering strangely pitched echo is hard to beat.
So what is happening is like an electronic noisemaker that repeats what it hears precicely out of phase , destroying the origional sound in a small area.
