I already made a bunch of simulations, not only this configuration but others as well. I will propably put them on my home page as soon as I find some free time.
What's the conclusion from looking at the numbers and simulations?
Floor and ceiling reflections are too early in time, too low in level and to close to the direct sound source to be of much value?
Should a speaker design avoid, enhance or ignore them?
Floor and ceiling reflections are too early in time, too low in level and to close to the direct sound source to be of much value?
Should a speaker design avoid, enhance or ignore them?
but if two wavefronts arrive at the ear at a different time then there is yet no phase relation but they are not sensed as one or are they? I think not but of coruse I may be wrong
Feynman etc. impressive and very wise
😕 😱but are there any simplified formulas that allow us to predict more-or-less precisely when there will occur a specular reflection? Having regard to the wavelength and the distance from the sound source to the reflective surface? 🙂
It took over 2000 posts for anyone to ask this crucial questions 🙂
and the award goes to ...Markus! 😀
Too early for conclusion, but meanwhile I disagree with unimportance of floor reflection.
It can be said that lifting midrange driver 1m above floor is not the way to go. Look at the floor and ceiling reflections in the post #2045. Floor reflection is very strong at the listening position, so is ceiling reflection. Certainly their affect timbre, if nothing else. I think there are other perception factors too.
Hello Elias,
Your wavetank simulations are interesting and are also useful to investigate the best position of the OB in the lateral direction.
Considering your simulation (without elevation), the OB should also be placed touching the lateral wall...
Best regards from Paris, France
Jean-Michel Le Cléac'h
Your wavetank simulations are interesting and are also useful to investigate the best position of the OB in the lateral direction.
Considering your simulation (without elevation), the OB should also be placed touching the lateral wall...
Best regards from Paris, France
Jean-Michel Le Cléac'h
Well, I actually worked on it over the weekend. Since I moved houses last year I always had a timbre and dynamic issue, the ceiling is low, only 2.3m high. I always suspected the ceiling so finally had a whole day to do take measures. So nice to see the graphs confirming it, massive reflexion at 3ms. I stacked some acoustic foam on top of the tweeter and bingo, the reflexion went 15db down.. How does it sound? I can play louder and don't have that terrible high midrange emphasis that made everything shout at me, and now a nice 10ms window to the first reflexion. 🙂
Conclusion? I don't think you'd want such an early strong reflexion, at least not on a forward firing setup. My 2c.
problem is not with the ceiling reflection as such but with that particular speakers in this particular configuration
I'm not sure how you define "wavefront" and I don't know how large your time difference is.
to make myself clear - my only point is that it is a matter of equalization - not of reflection, spectral, not temporal
You have
so the effect of it on the tweeter's "30-50 ms" response can be measured at the listening position, right?
I also disagree with myself ! 😛
At first I thought ITD for direct sound and floor reflection would be the same. Now I see they are not, except for the median plane.
The ITD difference between direct sound and floor reflection is at maximum when speaker is at the side (90 deg).
Here a simple scetch, can see the path difference between direct and reflected sound is higher for the real speaker and smaller for the reflection. This is to say that ITD is higher for real speaker and smaller for the floor reflection.
All the other angles between the median plane and the 90 side causes also ITD altough the value is less than in this extreme side case and diminishing to zero towards median plane.
- Elias
At first I thought ITD for direct sound and floor reflection would be the same. Now I see they are not, except for the median plane.
The ITD difference between direct sound and floor reflection is at maximum when speaker is at the side (90 deg).
Here a simple scetch, can see the path difference between direct and reflected sound is higher for the real speaker and smaller for the reflection. This is to say that ITD is higher for real speaker and smaller for the floor reflection.
All the other angles between the median plane and the 90 side causes also ITD altough the value is less than in this extreme side case and diminishing to zero towards median plane.
An externally hosted image should be here but it was not working when we last tested it.
- Elias
welcome in our highly exclusive club!
😀however not when you tilt Your head 🙂
Elias, yes, that's what my numbers show too. In the median plane the cone of confusion becomes the median plane itself.
Anyway, the ceiling and floor reflections are close to the cone of confusion.
Anyway, the ceiling and floor reflections are close to the cone of confusion.
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Coding FDTD equations is such a great fun I would propably do it without a purpose too 😀