Sound down a tube (eg shotgun mic)

[Athiril]

I want to be able to figure out how sound works down a tube.

Leading to me being able to calculate where I should place slits on a tube and at what size given a tube diameter (and length if necessary) to make a good shotgun mic tube.

The slits allow wave cancellation.

So there is some internal reflection and also diffraction going on.. would like some kind of pointer on this.edit: did find this stating slit pattern is not important, but diameter is. Etc.

http://bioacoustics.cse.unsw.edu.au/archives/html/naturerecordists/2004-04/msg00143.html

 

[LightHero]

To answer your question, the key to understanding how sound works down a tube is an understanding of wave behavior. In particular, the principles of reflection and diffraction are important for understanding how sound behaves in tubes of different sizes and with different slit patterns. When it comes to calculating where and what size slits should be placed on a tube to make a good shotgun mic tube, it is important to understand the concept of wave cancellation. Wave cancellation occurs when two waves of equal magnitude and opposite phase interact, resulting in a net amplitude of zero. This can be achieved by making sure that the length of the tube is an odd multiple of a quarter wavelength of the sound being produced. This will ensure that the waves reflecting off of the end of the tube will be 180 degrees out of phase, resulting in wave cancellation. Additionally, the diameter of the tube and the size of the slits will affect the amount of diffraction occurring at the slits, which can also affect the wave cancellation. In general, the pattern of the slits is not as important as the diameter and length of the tube, as the latter two parameters have more significant effects on the behavior of the waves. For more information on designing a microphone tube, you may want to consult the literature on acoustics such as the books mentioned in this article: https://www.acoustics.org/press/152nd/snyder.htm