Timeline for Simulation of a pressure field developed by a song
Current License: CC BY-SA 3.0
8 events
| when toggle format | what | by | license | comment | |
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| Apr 20, 2015 at 16:11 | comment | added | teatime | Ok, despite the potential physics clusterfuck, this did lead me to a good place, though I just used the normalised votages from the wav file - hilbert be damned. I did this because I did the hilbert transform on the wav, and listened to it, no difference to my ears, so the minutiae of how it chances the signal seems to be unneeded. Having implemented this in the simulation I've gotten some really nice and smooth plots :) Jazzmaniac, I am just interested in making nice looking visualisations, albeit ones with some footing in reality. Thanks a lot for both your help. | |
| Apr 20, 2015 at 16:02 | vote | accept | teatime | ||
| Apr 20, 2015 at 15:21 | comment | added | Jazzmaniac | You are aware that Hilbert envelopes are fundamentally acausal? | |
| Apr 20, 2015 at 15:16 | comment | added | JRE | Yes, it doesn produce the shells you are discussing. No argument. If you now place a plane across your shells, you will get the rings I've been trying to describe, which the OP specifically mentions. I did, however, miss that the OP wants to use multiple speakers. That only means that you have to do sums from each speaker at each point on the plane. The Hilbert doesn't give you average power (or amplitude,) though you can get it from averaging the results. It gives you instantaneous amplitude for specific samples, which I think should give you better time and space resolution. | |
| Apr 20, 2015 at 15:06 | comment | added | Jazzmaniac | Your physics is way off, as is the suggestion that average power and instantaneous Hilbert envelope magnitude have any relation. The OP also explicitly asked for a model of a point like source. Such a geometry inevitably does produce spherical shells of constant pressure or displacement. The accurate answer to his question is so simple that I really wonder what point you try to convey by making the answer so complicated and also physically wrong. | |
| Apr 20, 2015 at 14:58 | comment | added | JRE | When the sound hits the flat surface, the sound pressure exerts a force on the surface which results in a deformation of that surface. This can be likened to determining the instantaneous power at that spot at that moment, hence the use of the hilbert transform to get the instantaneous amplitude. The simple ring display (obviously) isn't a good simulation. The calculated time of arrival for various angles is more realistic, though probably not really all that accurate. Since the OP's ultimate goal is "pretty picture drawing," inaccurate physics/mathematics need not be a hindrance. | |
| Apr 20, 2015 at 14:49 | comment | added | Jazzmaniac | The method you suggest might give a nice looking visualisation, but has nothing to do with the physics of sound propagation. Where would the instantaneous power come from? Or what component of the speaker-field system performs a Hilbert transform? If you read the OPs question so that he wants the mean field pressure instead of the actual microscopic oscillating pressure changes, then averaging the pressure over a finite spatial region would be the way to go. | |
| Apr 20, 2015 at 12:23 | history | answered | JRE | CC BY-SA 3.0 |