Diffraction of Sound Waves Through Slit

In summary, the equation that can be used to calculate diffraction for sound waves is Fraunhofer's Single Slit equation. This equation was originally developed to calculate the diffraction of light waves, and it is based on the principle that waves propagate as spherical waves. However, because sound waves are spherically expanding waves, the usual 1/r^2 dependence of spherically expanding waves is not practically useful for calculating diffraction. Instead, numerical simulations are required to calculate diffraction for sound waves.
  • #1
gex
37
2
Hi there,

I have a scenario in which different frequencies will be played behind a curtain with a 2m opening. I would like to calculate the angle of diffraction for different frequencies played by the piano. One equation that I came across through research is Fraunhofer's Single Slit equation. (http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html) I am just curious as to whether I can apply this to sound even though it was developed for light waves.

-Thank you in advance.
 
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  • #2
Formulas apply, yes. Notes:
the curtain probably isn't a 100% barrier...
the waves at the 2 m opening will probably not be all that plane waves
echos and other acoustics will smear out the results
 
  • #3
Thank you for your response BvU, so to clarify, even though a certain frequency might not diffract far enough to reach a certain point on the concert hall, its reflections off of walls will cause it to eventually reach that point?
 
  • #4
Yes. In agreement with practical experience, I would say. It takes an effort to achieve minima with sound waves: best bet is two speakers and a sine wave. A curtain with an opening is far from ideal. And a piano is a complicated source. But: experiment ! Who knows.
 
  • #5
Cool! Thanks a lot for your help BvU, but if you don't mind I have one more question. Is it possible to quantify the loss in sound intensity as it travels to the back of the concert hall and gets reflected back?
 
  • #6
My estimate is you have to turn to numerical simulations rather soon. Don't think the usual 1/r^2 dependence of spherically expanding waves (i.e. from a point source) is practically useful.
Note that the section on acoustics doesn't even mention diffraction... (but the encompassing sound section does...)
 
  • Like
Likes gex
  • #7
Perfect, thanks a lot for all your help BvU! :wink:
 

Related to Diffraction of Sound Waves Through Slit

1. What is diffraction of sound waves through a slit?

Diffraction of sound waves through a slit is a phenomenon in which sound waves bend and spread out when passing through a narrow opening or slit. This results in the sound waves being heard in areas that would not normally receive direct sound waves.

2. How does diffraction of sound waves through a slit occur?

Diffraction of sound waves through a slit occurs due to the interaction between the sound waves and the edges of the slit. As the sound waves pass through the slit, they encounter resistance from the edges, causing them to bend and spread out.

3. What factors affect the diffraction of sound waves through a slit?

The main factors that affect the diffraction of sound waves through a slit are the width of the slit, the wavelength of the sound waves, and the distance between the slit and the observer. A wider slit, longer wavelength, and shorter distance will result in greater diffraction.

4. What is the significance of diffraction of sound waves through a slit?

The significance of diffraction of sound waves through a slit lies in its ability to allow sound to be heard in areas that would otherwise not receive direct sound waves. This can be useful in situations where sound needs to be directed to a specific location, such as in concert halls or auditoriums.

5. How is diffraction of sound waves through a slit different from other forms of diffraction?

Diffraction of sound waves through a slit is different from other forms of diffraction, such as light diffraction, because sound waves have longer wavelengths and lower frequencies. This means that sound waves are able to diffract around larger objects, making the effects of diffraction more noticeable in everyday situations.

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