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Does the first reflection point actually matter??

Hello my friends,

So please read the whole post before commenting. The question is nuanced.

First, as you probably know I’m a huge fan of the well treated room, and a fan boy of GIK acoustics as a result, so what I am _not_ arguing is against proper room treatment. I remember many years ago, perhaps in Audio magazine (dating myself?) the concept of treating the first reflection points came up, and it seems really logical, and quickly adopted. Mirrors, flashlights and lasers and paying the neighbor’s kid (because we don’t have real friends) to come and hold them while marking the wall became common.

However!! In my experience, I have not actually been able to tell the difference between panels on and off that first reflection point. Of course, I can hear the difference between panels and not, but after all these years, I want to ask if any of you personally know that the first reflection point really matters more than other similar locations. Were we scammed? By knowing I mean, did you experiment? Did you find it the night and day difference that was uttered, or was it a subtle thing, and if those panels were moved 6" off, would you hear it?


Best,


Erik
erik_squires
ozzy's avatar
ozzy
7,213 posts
 
I am using Stillpoints Aperture 2's at first reflection point but they really clicked into place when I added another set of Apertures in the center, between the speakers that is.

ozzy
tony1954's avatar
tony1954
892 posts
 
Personally I never quite understood the idea of the "first reflection point", but simply deferred to popular opinion. If speakers generate sound in a cone-shaped pattern in both horizontal and vertical planes, then why is the first reflection on the adjacent wall any more impactful on SQ than the first reflection point anywhere along the edge of the sound wave.
mahgister's avatar
mahgister
12,581 posts
 
Because acoustic equations ask for some origin point in space and time...

But sound is not reducible to physical linear waves equations only, like many other phenomenon....

« The ears speak» -Groucho Marx

then why is the first reflection on the adjacent wall any more impactful on SQ than the first reflection point anywhere along the edge of the sound wave.
Because of the timing aspect.....

But i created my room acoustic without being slave to  an equation, on the contrary not obeying to the sound wave, i decide to command to the sound wave... This is active device controls of the room....
sandthemall
543 posts
 
I used a lot of formulas but a simple one that gets you 'good enough' to start from is 1/5 from the sides walls and 1/5 from the back wall.  I got best imaging closer to the back wall and a little further from the side walls. Start with best speaker/audio rack placement and no acoustic support...get the best sound and then move on to the surfaces.
brownsfan
1,508 posts
 
@tony1954, we are more sensitive to localization clues in the horizontal plane.  Most of us have our ears mounted on the side of our head, not the tops and bottoms.  :)   So early reflection points on the side wall tends to be most impactful,  Back walls that are close to the main listening position can also be more impactful in terms of confusing localization clues.  In certain cases where a room is very wide or where the main listening position is well removed from the rear wall, floor and ceiling can be more impactful.  Conventional wisdom is that you would like to have all reflections arriving at the ear with a delay of 5 to 20 milliseconds down 20 dB relative to the direct signal.  Reflections arriving at the ear within that window tend to smear the localization clues provided by the direct signal.  Reflections earlier than 5 ms tend to merge well with the direct signal, and those reflections arriving later than 20 milliseconds tend to be perceived as separate echos adding to the spaciousness of the room. 
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