Sound Interference Experiment: Explaining Intensity Increase

[jaumzaum]

I cannot understand the following:

Imagine you have 2 sound sources and build up an interference experiment, where far away from the sources you have a receptor. Imagine you put the receptor at the same distance from the sources. If you turn off one source the receptor will receive a sound of intensity I, if you turn both on the intensity will be 4I, why is that? I can understand that for the light experiment, as the intensity depends on the square of the electric field, but how can I expain that for the sound?

 

[Simon Bridge]

What is the relationship between intensity and amplitude for sound?

 

[jaumzaum]

I don't know :(
Is there a physical formula that relates the amplitude with the intensity?

 

[Simon Bridge]

Have you tried looking it up?
http://en.wikipedia.org/wiki/Sound_intensity
... the intensity of sound waves is proportional to the square of the amplitude - like with any waves.

 

[sardar]

In this interference experiment, the phenomenon of sound interference can be observed. When two sound waves from different sources meet, they can either reinforce or cancel each other out, depending on their relative phases. In this case, when both sources are turned on, the sound waves are in phase and reinforce each other, resulting in a higher intensity of sound at the receptor.

To understand this increase in intensity, we can look at the mathematical equation for sound intensity, which is given by I = P/A, where P is the power of the sound wave and A is the area over which the sound is distributed. When two sound waves meet, the power of each wave adds up, resulting in a higher total power at the receptor. Additionally, the combined area over which the sound is distributed also increases, resulting in a higher intensity of sound at the receptor.

In other words, when two sound waves interfere constructively, the total power and the area over which the sound is distributed both increase, leading to an overall increase in intensity at the receptor. This phenomenon can be explained by the principle of superposition, which states that when two or more waves meet, the resulting wave is the sum of the individual waves.

Therefore, in this interference experiment, the intensity at the receptor is 4 times greater when both sources are turned on because the power and area of the sound waves are adding up, resulting in a stronger and louder sound. This is similar to the concept of constructive interference in light experiments, where the electric fields of two waves add up, resulting in a brighter light.

In conclusion, the increase in intensity observed in this sound interference experiment can be explained by the principle of superposition and the mathematical equation for sound intensity. By understanding the behavior of sound waves and their interactions, we can better explain and predict the results of interference experiments.