a precedence effect in the vertical plane? Can You give any reference for this too? Please be so kind
Any wave interference/addition/superposition applet on the net is a reference. Here is one of the nicer examples:Can You please give any reference for this? In English if possible
Wave Interference
well, very nice but I thought Your argument was from psychophysics and psychoacoustics, You know, when You say "Gestalt" etc. Was "Gestalt" taken into account in this nice applet?
and what about the precedence effect in the vertical plane?oh c'mon Scott!
what I don't know is what You mean by "the point of diffraction"
-that if it weren't for the length of the wavelength vs the size of the object it would be a reflection.
Nobody seems to reference reflection in the context of wavelength, but it's a necessary distinction from diffraction.
Ex. a 250 Hz wave diffracts around your body while a 1000 Hz wave reflects off of your body. Ergo: If a 250 Hz wave diffracts around your body it's not reflecting.
-that if it weren't for the length of the wavelength vs the size of the object it would be a reflection.
Nobody seems to reference reflection in the context of wavelength, but it's a necessary distinction from diffraction.
Ex. a 250 Hz wave diffracts around your body while a 1000 Hz wave reflects off of your body. Ergo: If a 250 Hz wave diffracts around your body it's not reflecting.
c'mon again!
I know that and You know that I know that I ask where is the formula that tells us that 500 Hz wave doesn't specularly reflect under the conditions of Elias' experiment?
c'mon again!
I ask where is the formula that tells us that 500 Hz wave doesn't specularly reflect under the conditions of Elias' experiment?
Sorry. I don't think in formulas.
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Sorry. I don't think it formulas.
???
Did I misuse the term?
"formula: Mathematics A statement, especially an equation, of a fact, rule, principle"
ok then - in other words: How can You tell that a 500 Hz wave doesn't specularly reflect under the conditions of Elias' experiment? Give some reasons please
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I think of a formula as a mathematical expression. Unless it's got a currency sign in front of it I can barely add 2 + 2.
To me it's more of a logic progression, or what I posted in 2104.
I tried ceiling deflectors in FDTD simulation.
The speaker is 40cm box with 30cm radiator. Freq 500Hz. Floor is removed and vertical walls are absorptive. x and y axes are in meters.
This type deflector does not remove ceiling reflection at the listening position, but it breaks the wavefront spreading the energy in time domain. A diffusor
- Elias
The speaker is 40cm box with 30cm radiator. Freq 500Hz. Floor is removed and vertical walls are absorptive. x and y axes are in meters.
This type deflector does not remove ceiling reflection at the listening position, but it breaks the wavefront spreading the energy in time domain. A diffusor
An externally hosted image should be here but it was not working when we last tested it.
- Elias
ok then - in other words: How can You tell that a 500 Hz wave doesn't specularly reflect under the conditions of Elias' experiment? Give some reasons please
500 Hz is 2.26 feet (using a wavelength calculator).
Acoustic center for the driver on-baffle virtually connected to the floor is within 2.26 feet. Within 2.26 feet the wavelength is bounded to the baffle and floor (in the same manner a large wavelength will bound to and diffract around a smaller object). If it's enough above this amount (as in the meter example) then sure enough - reflection for this wavelength. Put enough of a delay on that reflection (again, relative to the wave's length) and you'll get an echo.
I tried ceiling deflectors in FDTD simulation.
The speaker is 40cm box with 30cm radiator. Freq 500Hz. Floor is removed and vertical walls are absorptive. x and y axes are in meters.
This type deflector does not remove ceiling reflection at the listening position, but it breaks the wavefront spreading the energy in time domain. A diffusor
Thanks! What happens when you place them like this:
Also try longer panels and/or closer together.
Attachments
It strange indeed. The measurements should reveal similar (15dB) difference as you measured on ceiling absorption.
Or are your speakers somehow nonconventional ?
Not at all, just a pair of Orions. I may be blind?
2m distance, mid heigh 87cm, tweeter height 107cm, mic at 1m, ceiling 2,25m.
pads on the floor only:
An externally hosted image should be here but it was not working when we last tested it.
pads on floor and on top of the speaker:
An externally hosted image should be here but it was not working when we last tested it.
Obviously one is missing, no floor, no ceiling pads. silly me.
I did think about a deflector on hinges first but it seemed too difficult on paper.
Are You sure?
Isn't it that for a reflection of a wave to occur the reflecting surface must be no closer than a quarter of a wavelength from a sound source?
The 500 Hz wave will be reflected. There is no doubt about it. If the floor is "mirror-like", the reflection will be specular. No doubt about that too.Originally Posted by graaf
ok then - in other words: How can You tell that a 500 Hz wave doesn't specularly reflect under the conditions of Elias' experiment?
Rudolf
then why would it be disregarded by a human auditory system?
once again a couple of links to information that a floor reflection is an important distance and elevation perception cue:
Francis Rumsey, Tim McCormick "Sound and Recording"
Linkwitz's 2009 AES Paper
Human Systems Integration Division @ NASA Ames - Projects
http://www2.ph.ed.ac.uk/teaching/course-notes/documents/67/1569-SoundLocalisation1.pdf
moreover:
Re: [Sursound] Distance perception
Did anyone say that it is disregarded?
In Elias' example it is almost a grazing reflection. That means, that the time difference between the initial sound and the reflection is quite short. And the angle between initial sound and reflection is narrow. Compare that to the wavelength of 500 Hz and tell us, what aspect of the reflection makes you still worry.
Rudolf
None of those links describe the frequency range of the floor reflection that affects the distance perception.
Here we are talking about low-mid freqs.
For normal living room environment, the situation I'm most interested, I think the ceiling deflectors are very unpractical and not appealing. There should be found another alternative method to achieve low floor (and/or/or not ceiling) reflection at the listening position.
in that particular reflection nothing really worries me
I am trying to understand the results of Elias' test:
it is clear that with 400Hz low pass and also 700 Hz low pass the shifting effect is not that severe - perhaps because the reflection is barely audible? and in turn perhaps this is because the angle is relatively narrow, the delay is relatively short and the wave is relatively long?
just a hypothesis