Question

How do you relate the principle of Superposition to sound? Why does some people in a big room, hear quiet sound?

Answer 1

• When two waves occupy the same point, superposition occurs. Superposition results in adding the two waves together.
• Constructive interference is when two waves superimpose and the resulting wave has a higher amplitude than the previous waves.
• Destructive interference is when two waves superimpose and cancel each other out, leading to a lower amplitude.
• Most wave superpositions involve a mixture of constructive and destructive interference since the waves are not perfectly identical.
• Important point-While pure constructive and pure destructive interference do occur, they require precisely aligned identical waves. The superposition of most waves produces a combination of constructive and destructive interference, and can vary from place to place and time to time. Sound from a stereo, for example, can be loud in one spot but quiet in another. Varying loudness means the sound waves add partially constructively and partially destructively at different locations. A stereo has at least two speakers creating sound waves, and waves can reflect from walls. All these waves superimpose. An example of sounds that vary over time from constructive to destructive is found in the combined whine of airplane jets heard by a stationary passenger. The combined sound can fluctuate up and down in volume as the sound from the two engines varies in time from constructive to destructive.