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Old 31st May 2012, 11:29 PM   #61
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Originally Posted by markus76 View Post
Hi David,

I'm not so sure about this because once you add head movement (and therefore HRTF-based directional "distortion") into the (aural) picture, height information (or the lack of) is probably of great importance for increased realism.
A reflection from the floor or ceiling is not going to give a sense of increased realism though. As Dave points out our binaural hearing can't easily separate the time delayed reflections that arrive from a different elevation but same azimuth, the result is comb filtering and sometimes a "stretching" of the apparent vertical size of the image.

The only hope we have to reproduce some actual height data in a stereo recording is HRTF related changes in the high treble frequencies, but most recordings made with normal mics would not encode such data, (unless added electronically as an HRTF effect during mixing) and floor/ceiling reflections are likely to corrupt any such HRTF encoded height data, not enhance it.

As far as I can see, floor and ceiling reflections are only harmful.
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Last edited by DBMandrake; 31st May 2012 at 11:33 PM.
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Old 31st May 2012, 11:31 PM   #62
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[QUOTE=boris81;3043847]It's not a U-Frame, it's technically a dipole with damped rear wave. [QUOTE]

Hi, is there a back panel on the "enclosure"? Its hard to tell from the sketchup image.

Do you think you are getting a raditation pattern somewhere between dipole and cardioid or super-cardioid?
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Old 1st June 2012, 01:37 AM   #63
boris81 is offline boris81  United States
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Originally Posted by samadhi View Post
Hi, is there a back panel on the "enclosure"? Its hard to tell from the sketchup image.

Do you think you are getting a raditation pattern somewhere between dipole and cardioid or super-cardioid?

Waveguie and Cardioid on a Slim Baffle

Post #50 describes the current state of the "enclosure". I decided to go open back and use "driver mufflers" to absorb some of the rear wave. I have trouble getting measurements from 90-160 degrees indoors but from what I was able to get I would say the response is supercardioid.

I was planing to do outside measurements this weekend but I found out the landlord is showing the upstairs apartment to potential tenants. It will not look good if they walk on me blasting sweeps in the backyard. It might be some time before I get reliable polars.
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Old 1st June 2012, 06:28 AM   #64
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Originally Posted by DBMandrake View Post
A reflection from the floor or ceiling is not going to give a sense of increased realism though.
It might or it might not. Nobody has ever shown which reflections from what directions are the most relevant for increased realism. Any reflection creates comb filtering yet we don't perceive it as such. Time is very relevant to our hearing.
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Old 1st June 2012, 03:00 PM   #65
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How do SPL and reflection intensity interact?

I've notice that low to medium SPL/reflections don't impart a confused sound whereas very high SPL/reflections do.
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Old 1st June 2012, 03:01 PM   #66
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Good question. Short answer: we don't know.
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Old 1st June 2012, 04:20 PM   #67
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I had imagined that as the reflecting surfaces area grew with SPL intensity .. the surfaces become too close together to form complete (sort of) waves at our listening position.

... that the polar response (area produced by a given SPL) .. in air ... is as a conduit for subsequent sound waves. Sound waves travel right out to the polar edge very quickly .. (waves riding waves). As the SPL increases ... so does the area of the "conduit"? .. and therefore the shorter the distance becomes to another reflective area?

Last edited by puppet; 1st June 2012 at 04:24 PM.
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Old 1st June 2012, 04:31 PM   #68
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Originally Posted by puppet View Post
How do SPL and reflection intensity interact?

I've notice that low to medium SPL/reflections don't impart a confused sound whereas very high SPL/reflections do.
Yep, that's my experience too. An excessively reflective/reverberant room becomes confused and overwhelming at high SPL, while the same or even higher SPL in a more damped room sounds fine, and both sound fine at low SPL.

Why ? I don't know, my guess is there is some sort of threshold effect in our perception of reverberation level, as SPL increases we pass that threshold sooner in a reverberant room.

I also notice that my subjective opinion of how reverberant the room is and perceived direct to reflected ratio changes with SPL level.
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Old 1st June 2012, 04:46 PM   #69
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Originally Posted by DBMandrake View Post
Yep, that's my experience too. An excessively reflective/reverberant room becomes confused and overwhelming at high SPL, while the same or even higher SPL in a more damped room sounds fine, and both sound fine at low SPL.

Why ? I don't know, my guess is there is some sort of threshold effect in our perception of reverberation level, as SPL increases we pass that threshold sooner in a reverberant room.

I do notice that my subjective opinion of how reverberant the room is and perceived direct to reflected ratio changes with SPL level.
I understand.

... was thinking when I posted above was that SPL intensity was like a balloon where the physics for sound waves on the inside might differ slightly from the sound waves physics outside the balloon. A perfect environment inside this cloud (waves appear at the edge almost instantly in all directions) .. until the balloons edge encounters another independent surface (brought on by increased SPL intensity). Then the "perfect environment" inside the SPL structure is upset.
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Old 1st June 2012, 08:18 PM   #70
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I understand.

... was thinking when I posted above was that SPL intensity was like a balloon where the physics for sound waves on the inside might differ slightly from the sound waves physics outside the balloon.
Well, physics stays the same regardless of SPL. What changes is our perception. There are little muscles in our ear that might have a bigger impact on sound perception than commonly thought.
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