I am going my physics extended essay and I am stuck in explaining my hypothesis. So I am doing an experiment where I have 2 sound sources emitting specific frequencies and I am trying to find fringe (first maximum or the point of constructive interference). Now the problem is I have to use theory to explain why the point of the first constructive interference will decrease as the frequency of emitted sound waves increases. Anyone have an idea please?

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    $\begingroup$ You have to ask yourself what interference is. Why does it occur and when? $\endgroup$ – my2cts Aug 14 '19 at 14:39
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    $\begingroup$ have a look hyperphysics.phy-astr.gsu.edu/hbase/phyopt/slits.html $\endgroup$ – anna v Aug 14 '19 at 14:42
  • $\begingroup$ What do you mean by "decrease"? Do you mean decrease in amplitude? Will the slit spacing and slit width remain constant as you increase sound frequency? $\endgroup$ – David White Aug 14 '19 at 17:23
  • $\begingroup$ Re, "2 sound sources emitting specific frequencies..." You're not going to find much of an interference pattern if the two sources are not emitting the same specific frequency. Your two sources simulate the two slits which, in the classic double-slit experiment, both would be illuminated by the same laser. $\endgroup$ – Solomon Slow Aug 14 '19 at 18:27
  • $\begingroup$ Also, the results may be hard to interpret if you don't perform the experiment in some approximation of an anechoic chamber. (Maybe out of doors with the sound sources suspended above a grassy field). Otherwise, reflections off the walls, floors, ceilings, and other surfaces will create a complex pattern--as if many additional sound sources were present. $\endgroup$ – Solomon Slow Aug 14 '19 at 18:31