Acoustic Horn Design – The Easy Way (Ath4)

This material would be preferred (for an axisymmetric ATH4). MDF is a suitable alternative, but requires several sealants/protective coatings.
 

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We still know less how you realized the free-standing calculations. Would you please show obervation fields for one of your free-standing calculations that we are able to assess what's going on inside and outside the horn.
Attached is the demo project. There are no observation fields yet but you can easily add as many as you want manually. At least you can inspect the freestanding conditions right away.
 

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Well it does display the intensity along an arc but some far-field features are indeed observable only in the far-field (this is 1.5 x 2 m)...

(BTW, the white area beind the waveguide doesn't mean that there's a boundary. The waveguide really stands in free air - just the observation field is not present there at the moment, which has something to do with how this particular simulation is constructed.)

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Maybe I should explain this in more detail as it is really not that intuitive.

This is the interior of our waveguide, nothing surprising here (gray=wall surface; red=driving elements):

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However, from the rear it looks transparent, and that's because it is actually acoustically transparent from the rear side of the surface - just as if it wasn't there (!):

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What we can do is to close the volume of the waveguide (which we have to do somehow) by adding a back side wall that is just a flat dics (!):

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...which looks like this if we turn off the display of the waveguide interior:

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From the front it then looks like this (the back side is visible but transparent again (!) - it's not really there):

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This is just a convenient way how to simulate a free standing horn without the need to model its back side in full detail...
 

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