[Fyron]

When 2 waves of energy pass through each other, they add or cancel, depending on their relative frequencies. But this is only when they are in contact. Once they pass through each other, they return to normal, unchanged. This can be seen by shining two flashlights in crossing paths. Where the beams meet, there will be up to 2x as much light. But after they have crossed, the individual beams are the same as they were before they met. This also happens with sound waves. I am not sure about other types of waves (such as waves of water), but I think they follow the same physics.