Does the first reflection point actually matter??

For what it is worth:

The wife and I bought a distressed 3.5 story townhouse in the city of Newburgh NY for super cheap and did a top down restoration.

Except for the top attic floor.

It is there that I have my home office, studio and listening room. The room is insulated with rock wool: 6 inches in the walls and 17 inches in the ceiling. There are two dormers and a gable to break up parallel wall and ceiling reflections. Not that I have much.

My architect, who I know from college days, has designed some recording studios. He told me not to seal the rock wool behind dry wall, but instead to simply cover it with burlap. This would give me a semi-anechoic room. No panels to position etc.

The difference in the sound quality from my old New York City loft - with its tin ceiling, brick walls and huge glass windows - is night and day.

For the amount of money that I was spending anyway to insulate my home to get it to perform to near net zero performance levels, I got the equivalent of a room that is recording studio quality.

The one issue missing from this discussion is your impression of acoustic treatment at first reflection points completely depends on how wide a dispersion speaker you actually use.  A speaker that narrows with frequency, say a horn, will send less info to the side walls as frequency increases.  A ribbon or any planar device will also do this but it can depend on what frequency the planar portion of the speaker is working in. 

So imagine a ribbon working at 3K and above.  You wont get as much energy at 3K and above on first reflection points as they get fairly narrow even at 3K and get even narrower as you get to 10K and above.  This is easily demonstrated by rotating the speaker until it almost faces the side walls, you'll hear bunch of splash as you get more energy on it.  Also the wall material matters- glass is very different frequency emphasis than wood.   There are many different types of absorbers- some work well at HF, and some work better at mids and some are built to be LF absorbers with membranes. 

SO there is no universal answer to this other than to say if you have a wide dispersion speaker, the first reflection point absorption is critical to improving image.   If you have a narrow dispersion speaker you may not hear much difference.  Also you need to buy real absorbers like GIK, or make them, I like the 4 inch thick ones, they absorb more for the same wall space.   

Brad 

Brad,

The one issue missing from this discussion is your impression of acoustic treatment at first reflection points completely depends on how wide a dispersion speaker you actually use.

For the purposes of this argument, alone, I want to argue that first reflection points don't matter, ever.

Again, I don't mean that room treatment doesn't matter.  I just argue that the idea that the first reflection points are some sort of magical acupressure point for speakers seems wishful thinking to me.

What does matter, a lot, is the overall acoustic field. An even decay rate and proper balance of diffusion and absorption.  But if you take a dozen panels placed around evenly in a room, I don't think you could tell that the 1st reflection points do anything more special than the rest.

And I am also _not_ making the argument that speaker to room acoustic matching doesn't matter, it does a great deal.

Best,

E

Yeh Brad that is a very valid point!

Some horns are symmetrical some have more width than height. That gives narrower spread up and down. And will result in less issues with ceiling and floor first reflection points. That I have experienced.

Eric I would put it like this. As we KNOW that the FIRST bounce (reflection point IS the strongest/highest in dB. Then it more energy (dB) that we can transform to friction with absorbing panels. And 2nd, 3rd reflection, and so on is, each decreasing in energy for each reflection that is done.

So if we only have 2 or 4 panels and want to absorb as much reflections from the room boundaries. Where should we places those few panels to get the most absorption as possible with those few panels? Yes at the strongest one of course.

If we wanted to preserve the side reflections but we wanted to absorb the same amount of dB but only treated the 2nd, 3rd and so on reflection points then we need much more coverage than what just 2 or 4 panels could contribute with.

So we see that first reflection points is giving us most bang per square unit of panel/treatment.

(As for me I want in general listen on what is in the recording and not get the "color" and delay of room boundaries.
The "color" is defined by what material the room boundaries consist of. We know that dry walls and concrete walls reflect different amount of dB for each frequency (frequency response). So we can consider that in a concrete there inside that wall sits a mixing engineer that use litle more level on the bass faders on his console compared to the mixing engineer in the dry wall.
Sorry for that dumb analogy.) :D