Destructive interference of a sound wave?

Question

A sound wave with intensity 25 mW/m^2 interferes destructively with a sound wave with intensity 28 mW/m^2. What is the intensity of the superposition of the two?

Answer 1

do they interfere with each other in or out of phase?

Answer 2

You have the answer staring you in the face. "superposition" means put one on top of the other, mathematically speaking. In other words, as sound is a P or compression wave, simply put the two waves into the same area at the same time and add up or subtract their intensities according to if they are constructive or destructive waves.

If the two waves were in constructive interference, the two intensities would build (construct) on each other because their waves would be in sync. That is, the expansion (contraction) cycle of one wave would be superpositioned over the expansion (contraction) cycle of the other wave. The two waves would be acting in the same direction at the same place, at the same time. Their effects would be additive. That would give us 53 mW/m^2.

But you are asking for destructive interference. This means that, when superpositioned, the expansion cycle of one wave is on top of the contraction cycle of the other (or vice versa). That is, the two intensities are oriented in opposite directions. Therefore, the expansion cycle of one wave would be superpositioned over the contraction cycle of the other one. And that means they are subtracting intensities. You can do the math.

Answer 3

i'm undecided what the discern sounds like, yet with 120Hz you will discover the wavelength. once you already know the wavelength you are able to then discern the distances at which interference happens. lambda=velocity/frequency, so the wavelength is two.86 m or 343/a hundred and twenty