Frequency and penetration depth

  • Thread starter Mathysics
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why does the increase of sound frequency will decrease the penetration depth?

how can this related to diffraction of sound?? Is it because they can be easily reflected??

need answer desperately, thx
 

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  • #2
Born2bwire
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Simply because the wavelength of the sound wave decreases with increasing frequency and the attenuation of the wave is dependent upon the depth of penetration in terms of wavelengths. Given the same properties at 100 Hz and say 1 KHz, the waves will be attenuated by the same factor if both of them penetrate 1 wavelength into a lossy material. The difference though is that the 1 KHz will have to penetrate less distance to cover a single wavelength versus the 100 Hz.

Physically the reason is more complicated. I am not too sure about the physical explanations of attenuation and reflection when it comes to sound waves as I do electromagnetic waves but the physics are the same. I could attempt at an explanation but I'm sure that some of the other posters can do it far more competently.
 
  • #3
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Simply because the wavelength of the sound wave decreases with increasing frequency and the attenuation of the wave is dependent upon the depth of penetration in terms of wavelengths. Given the same properties at 100 Hz and say 1 KHz, the waves will be attenuated by the same factor if both of them penetrate 1 wavelength into a lossy material. The difference though is that the 1 KHz will have to penetrate less distance to cover a single wavelength versus the 100 Hz.

Physically the reason is more complicated. I am not too sure about the physical explanations of attenuation and reflection when it comes to sound waves as I do electromagnetic waves but the physics are the same. I could attempt at an explanation but I'm sure that some of the other posters can do it far more competently.

ok thx that was very useful!
 

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