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
Few people know that Goethe make his point against Newton in color theory....While Newton search for a theoretical mathematical corpuscules light theory, Goethe described for the first times in history the way of colors to comes from light and dark in the world in relation to physiology....Goethe was a colossus of intelligence but in too much fields for the average people to understand him really....And to this day, Goethe reflexions seems not to go to a dead end, like a corpuscule theory of light and colors... Edwin Land was a Goethe disciple for example.... :).

In acoustic there is something similar....And Michael Green put it right by noting that sound is also pressure, not an abstract mathematical wave only, but a living wave....
We exist in a universe of waves...beginning with the subatomic, density and type variants all....

It just 'thins out' the further off we rise from what we percieve as solid ground.

And we're just another version of it, making waves of our own.

"What state do you live in?"  Quantum....

"Zip code?"  (Hand over a thumb drive...)

J'accuse:  The number of things agreed upon = the number not.
The universe is subject to the Bell Curve as much as we 'average out' in our HO about what we hear, how we hear it, and how we feel (or don't) about it ....

Flies in the fluxes of universal ambers...in the midst of all the other waves...the daily surf...

Not terribly sci about it, but it makes for my day. *S*
I were thinking about..
If we ONLY look at the side walls reflections.
Then the first reflection points that the sound bouncing off.

My thoughts goes like this:
First reflection point is weaker (lower dB) than the direct. And what reflects of that surface is probably more higher frequencies than lower ones (Hz). 

That side point will act as a muted bass shy speaker that is delayed as it were placed further away..

Can this side walls reflection points contribute to a wider sound stage?
Or some other benefits that can be a argument to not treat side walls reflections?

(And of course the our experiences will vary greatly when we have all different distances from the speaker to the side wall in our unique rooms. So I would like to know what distance is used when we tell about our experience.)

A experience I have (sidewalls 80 cm away) it is like that helps or make it possible to hear sounds/instruments somewhere between the speaker and the first reflection point.. so extreme right or left will be beyond the speaker. Yes now when I think about it the sound stage is then wider.. 

But it is unintended wider and nothing the artist/producer were aiming for. And when first reflection point reflect a uncontrolled frequency response/range depending on what type of surface the effect will be more or less pronounced depending on the different frequency range different instruments has..

So I think I have answered my own question somewhat.. but how are your thoughts on this?
optimize, some of your points have been addressed in previous responses.

That side point will act as a muted bass shy speaker that is delayed as it were placed further away..

Can this side walls reflection points contribute to a wider sound stage? 
Or some other benefits that can be a argument to not treat side walls reflections?

Because of how our brain processes reflections, how we perceive reflected sound depends on how long those reflections are delayed compared to the direct path from source to ear.  If the path of the reflected sound is longer than about 6 meters longer than the direct path from the source to the ear, the reflection will add to the spaciousness of the room.  Any reflection that is shorter than that will generally not be distinguished as a separate sound and will result in a spacial smear.  Another consideration is that the dB level of sound decreases as the distance increases, and the dB level further decreases every time it bounces off of another surface.  It has been my experience that reflections that have a path about 2-4 meters longer than the direct path are especially detrimental to precise localization of instruments and voices if those reflected signals are not at least -20 dB compared to the direct sound.  

So the answer is that some reflections off of side walls are beneficial, and some are detrimental.  I have left the sidewalls of my room untreated from about 0.5 meters forward from the first reflection point to the front corners.  Doing so gives me better sound stage width at the expense of increased slap echo.  I've devised a way to deflect the first reflection point away from the ear, which results in superb imaging in my rather narrow (~4.5 meter wide) room.  My approach is different than traditional absorption or diffusion.  It is more consistent with the approach described by Duke LeJuene above. 

The first sidewall reflection point matters in the design of a recording studio control room. Those I have been involved in used angles which direct the reflections away from the normal listening position.
If I read your post right, your room is less than 2 M wide.   I don't know how your room is laid out otherwise, but it seems likely to me that your side wall first reflection points have a delay of less than 5 milliseconds compared to the direct signal.  Some say that those very short delays don't compromise imaging as much as those having a delay of 5-20 milliseconds.  So you may not get much benefit from trying to treat your sidewall first reflections as others.  


We can clearly say it is more than "some".
More exactly half of all reflections is good and the other half is harmful for stereo image.

Experiment: 
Put a wall of panels from your face in sweet spot that extends right in the middle to your front wall between the speakers.

The sound stage is incredibly and will never be better than this.. ..yes it looks stupid and is impractical but just as a experiment.

In short we have one room for left and another for right and the reflections from each speaker is there BUT they are totally separated.

That shows us how "harmful" to the sound stage perception, the first reflection point from the right speaker in the left wall that reach the left ear.. that were intended for the other ear.. and vice versa.

So half of all reflections (when we can see the experiment as we have two separate rooms left and right) is not good or is just destroying the sound quality. And if you have done the experiment then you will most likely agree.