- Hey Professor lens! I just got some noise cancelling headphones for my birthday and I have been wondering how they work. Mind explaining?
- Of course! So first I will have to explain constructive and destructive waves. Constructive waves occur when two waves line up. This allows a normal sound to occur.
- Oh I see so this is what allows me to hear things.
- What is a Pi shifted wave Professor?
- Yes but this doesn't explain your problem. If you add a Pi shifted wave things get complicated.
- What do you mean 0?
- A Pi shifted wave is when a wave starts at a minimum instead of a maximum.Now if you combine the two waves the peaks of the waves will line up with the troughs.Causing them to always be at absolute 0.
- Well at the points of a wave one wave will be at some peaks while the other wave might not be. The points they hit are numbers and when you use those numbers by adding or subtracting you would get the numbers of the wave they would make when combined.
- Pretend this is a wavelength, see how they intervene? That's what it looks like
- I'm starting to understand, but what about destructive waves?
- The Wave length you just saw was a deconstructive sine the valleys matched with the peak
- They always have a +1 and a -1. Which means they add up to 0. This causes them to cancel out leaving no sound at all.
- I think I'm getting it now, thanks Professor Lens!
- So when a sound enters your headphones they emit a pi shifted sound wave to cancel out the sound!