Sound diffraction

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Gif_Difracción del sonido.gif

First of all my respectful greetings to all the academic community of, we continue with expanding the knowledge related to the essential phenomenon of sound.


The sound waves that reach our ears propagate in any direction, any sound when emitted from a particular source and then travel through the material or elastic medium such as air will usually find on its way with certain obstacles and they cause other intrinsic phenomena to be carried out to this propagation and among which we have already analyzed the phenomenon of reflection, absorption and transmission, and this time we will analyze in general the phenomenon of sound diffraction.

The phenomenon of sound diffraction originates when certain sound waves come to surround an obstacle that they get in their way, but also occurs when these waves manage to pass through a small hole, of course, it is important to note that the development of sound diffraction will depend on the relationship between the wavelength of these sound rays and the size of the obstacle or hole, the above aspects will depend on the diffraction of certain sound waves and this can take place either within an enclosure or outside it.

Sound diffraction

This phenomenon as well as the other phenomena analyzed above (reflection, absorption, transmission) can be found in any space-time where we are, however my dear readers, when focusing on the phenomenon of diffraction we can express that when a sound wave front propagates from one side to another, the phenomenon of diffraction can develop, and this could be due to the fact that these waves surround a body or object that hinders their propagation or because they can pass through a small hole or orifice.

Therefore my friends we can say that when the sound waves go from one side to another generally will get certain objects on their way either large or small in relation to its wavelength, and that relationship makes the phenomenon of diffraction is small or large scale, then you can observe this phenomenon by passing the sound waves through a hole, where, vary the size of the hole to highlight the impact of diffraction as shown in Figure 1 below.

Figure 1. Sound diffraction


In the previous figure we could clearly observe two types of diffraction of certain sound waves when passing through either a small hole or a larger one, with greater diffraction in the smaller hole.

Now you can witness the same diffraction phenomenon but when these waves reach a certain body or obstacle in their path, as shown in figure 2 below.

Figure 2. Diffraction of sound on a wall, acoustic shadow area


In the following figure 2, we can clearly see how the wall or barrier reduces the sound intensity in the place where the receiver of the sound waves is located, highlighting also that it originates what is called an acoustic shadow and it will be related to the mobility of the wall or barrier, but it will also depend on the length of the waves that carry the sound at this moment.


Sound is part of our existence as we have been verifying in each of the previous publications related to the phenomena of reflection, absorption, transmission and now diffraction, and of the latter we could observe its action in the previous figures 1 and 2, where certain sound waves got in their way obstacles or holes that served to develop the phenomenon of diffraction.

This phenomenon could be captured in any area of our existence, although our eyes cannot observe it, however, our auditory systems are able to do so as long as the sound waves are within the spectrum audible to our ears.

Until another opportunity my dear friends.

Note: All images are my own and were created using Power Point and the animated gif was created with the PhotoScape application.

Bibliographic References

[1]Física del sonido.

[2]Sound diffraction at a trailing edge.