Good sealing of loudspeaker cabinets is required for similar reasons.Īnother implication of diffraction is the fact that a wave which is much longer than the size of an obstacle, like the post in the auditorium above, cannot give you information about that obstacle. Good soundproofing requires that a room be well sealed, because any openings will allow sound from the outside to spread out in the room - it is surprising how much sound can get in through a small opening. Besides being able to hear the sound when you are outside the door as in the illustration above, this spreading out of sound waves has consequences when you are trying to soundproof a room. This aspect of diffraction also has many implications. You may perceive diffraction to have a dual nature, since the same phenomenon which causes waves to bend around obstacles causes them to spread out past small openings. There are other factors such as the higher air absorption of high frequencies involved, but diffraction plays a part in the experience. The thunder from a distant strike will be experienced as a low rumble since it is the long wavelengths which can bend around obstacles to get to you. The thunder from a close bolt of lightning will be experienced as a sharp crack, indicating the presence of a lot of high frequency sound. Another common example of diffraction is the contrast in sound from a close lightning strike and a distant one. The fact that diffraction is more pronounced with longer wavelengths implies that you can hear low frequencies around obstacles better than high frequencies, as illustrated by the example of a marching band on the street. Diffraction in such cases helps the sound to "bend around" the obstacles. The fact that you can hear sounds around corners and around barriers involves both diffraction and reflection of sound. Important parts of our experience with sound involve diffraction.
That principle is none other than the principle of the diffraction of light.Diffraction of Sound Diffraction of Soundĭiffraction: the bending of waves around small* obstaclesand the spreading out of waves beyond small* openings.* small compared to the wavelength So next time you see a rainbow pattern on your CD/DVD, try to understand the principle of the phenomenon behind it. You might not even be aware of the fact because you are so accustomed to the phenomenon. So you see that you see several examples of diffraction in your very own daily life. There are also several other insects having very fine regular structures where diffraction of light occurs. The iridescent color of peacock feathers,.There are various other examples of diffraction grating present in nature that are: This is mainly due to the diffraction of light from the meat fibers. Luncheon meat appears to be a little iridescent. Speaking into a microphone is a good example of diffraction of sound in daily life. The setting sun appears to be red because of the diffraction of light from dust particles in the atmosphere. The setting sun is also a good example of the diffraction of light. You’ll see that your friends inside your classroom will hear you speak. A simple way of explaining this phenomenon is to stand and talk in the hallway adjacent to your classroom. The sound spreads as well as fills the room on the other side of the door. Radio waves bend around buildings and hence, the reception is still good on the opposite side.ĭiffraction of sound waves occurs when these waves pass through a door. Radio waves (specially AM) diffract when they come in contact with buildings. This effect is much less defined than the ones seen in a CD/DVD but it actually happens which is our point here. A standard vinyl record, when seen from a low angle perpendicular to the grooves, might actually provide a rainbow-like effect. The similar effect discussed above can also be seen in a standard vinyl record.
The closely spaced tracks on a CD/DVD act as a form of diffraction grating to form the rainbow pattern. The surface has the application of a thin layer of metal that makes the pits more visible. One surface of a compact disk/DVD has many tiny pits in the plastic that are arranged within concentric rings. This rainbow pattern effect is mainly a side effect of their manufacture. The rainbow pattern that you see on compact disks or DVDs is also a good example of diffraction of light.
You’ll see the seven colors of the rainbow, on the hologram of a credit card/ debit card or other similar cards that exhibit such holograms. Let’s go through them without further ado. We have highlighted a few examples of diffraction of light/sound/radio in our daily life. This phenomenon is basically the bending of light around the corners of an aperture or an obstacle. Diffraction refers to those phenomena that occur when a wave encounters an obstacle.