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Why can't this be easier?

ohnonotagain

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Feb 27, 2022
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As I sit here having measured the size and shape of my room and its acoustic response, wondering where the reflections are coming from in an L-shaped room with a desk and all manner of other furniture in it, getting to the stage where I have to start engaging trial and error and figuring out how to do that without sticking things irreversibly to the wall or ceiling, and I can't help thinking: it's 2024, this should be at least a bit less manual by now.

I have an iPad Pro with a built-in LiDAR which can generate a 3D scan of a room. I have a measurement microphone and software that allows me to analyse the frequency response of the room. Surely it wouldn't be beyond the wit of man to combine the two? Do a 3D scan of the room, do a frequency sweep measuring from the listening position, and when you put the crosshairs on a given frequency, indicate where in the room the reflections come from for peaks and nulls? Maybe even show the effect on frequency response of adding various kinds of panel in different places in the room?

As far as my Googling shows, there isn't anything that will do the whole thing joined up end-to-end. You'd have thought a manufacturer of acoustic treatment would have realised they could earn a good deal of business by showing people how to use their products. I'd pay good money to save my time and be confident of a good result. (And they'd get my money instead of me playing around with some spare Rockslab Sonic that I had lying around to see if it's worth making panels out of.)
 
Rock mineral wool is very efficient, it'll work nicely. It's just not pretty and it's quite nasty stuff to handle and breath. But I guess we're talking about a consumer friendly product here.
 
Do you realise that in REW you can view the reflections and their distance (minus the speaker to listening position) in metres? And you see what are the worst (early and loud) reflections to deal with first.
 
Do a 3D scan of the room, do a frequency sweep measuring from the listening position, and when you put the crosshairs on a given frequency, indicate where in the room the reflections come from for peaks and nulls?
You may be misunderstanding room modes.

When you have a strong bass peak at 78Hz or whatever, that's not a particular part of your room, like the right-hand side wall, that's emitting said peak.

It's the inherent dimensions of your room that cause a standing wave at 78Hz, and you are coincidentally sitting in the constructive part of said wave.

No amount of rockslab applied to any part of your room will fix that peak.
 
You may be misunderstanding room modes.

When you have a strong bass peak at 78Hz or whatever, that's not a particular part of your room, like the right-hand side wall, that's emitting said peak.

It's the inherent dimensions of your room that cause a standing wave at 78Hz, and you are coincidentally sitting in the constructive part of said wave.

No amount of rockslab applied to any part of your room will fix that peak.

Do you mean to write "not always a particular part of your room". Reflections off the right-hand wall will cause peaks and nulls too?
 
Yes but it is the main axial modes, length,width, height which are/can be the most destructive.
And if you have a pair of speakers whose on and off axis response are similar then side wall absorption becomes moot.
Keith
 
Yes but it is the main axial modes, length,width, height which are/can be the most destructive.
And if you have a pair of speakers whose on and off axis response are similar then side wall absorption becomes moot.
Keith

Agree on the first point, I think "strong" is the bit I missed in @staticV3 post

Disagree on the 2nd point, it is moot (I suppose) in a big enough room. Side wall reflections totally wreck clarity and soundstage within the first 20ms if loud enough and not even, based on personal experience. More so if off axis response is similar (intuitively not based on experience).
 
Just depends on the FR of the speaker, if a design has a ‘rough’ off-axis then yes it might well benefit from absorption but if the speaker has an off axis which mirrors the on ( contemporary active designs for example) then absorption isn’t necessary.
Keith
 
You have the REW room simulator tho for square shaped rooms. You also have table (from VBA) to show you first three peeks and deaps based on actual measurements (with measurement microphone) and do averaging for the first one in order to deal with it and lower the impact on rest (similar to helm resonator [bass trap]/opposite sub's 180° phase high methods but for free).
Reed: https://www.audiosciencereview.com/...modes-in-rew-measurements.53174/#post-1922366
So it's virtual bass area FIR + PEQ afterwards and preserving good impulse response.
 
Just depends on the FR of the speaker, if a design has a ‘rough’ off-axis then yes it might well benefit from absorption but if the speaker has an off axis which mirrors the on ( contemporary active designs for example) then absorption isn’t necessary.
Keith

I think you are talking in an idealised scenario where the right and left reflections arrive in a similar fashion and at similar times. And where the room is of a particular size and shape, probably not L shaped like the OP. There is no doubt for me that the absorption I have makes a massive difference. To my ears and rudimentary measurements. Would you insist that absorption is moot if the right wall is closer to both speakers than the left wall?
 
HI

I find the idea fascinating. That would be a most useful software.
I don't know enough about software development to comment on the feasibility or cost ( a non-trivial concern) of such an undertaking, but it would be useful.

Peace.
 
Yes but it is the main axial modes, length,width, height which are/can be the most destructive.
In a rectangular room with symmetrical layout, yes, but even then it is not a particular spot on the wall that creates the mode.
And in an L-shaped room the mode structure is more complicated, there might be no more length and width mode but combined ones.
And if you have a pair of speakers whose on and off axis response are similar then side wall absorption becomes moot.
Keith
Early (and strong) lateral reflections have a major impact on sound (SBIR) and soundstage. If the reflections are sufficiently smooth and symmetrical (L-shape again?) then the effect might be rather benign and even preferable with some recordings but with others it might not. Absorption or diffusion is rarely moot.
 
Perhaps not totally moot but my experience from last L-shaped room was that they were not the main issue. Surprisingly minor.
 
It's the inherent dimensions of your room that cause a standing wave at 78Hz, and you are coincidentally sitting in the constructive part of said wave.
I was under the impression that these standing waves relate to one dimension of the room (as opposed to the volume of the room), and thought based on that that using panels that effectively change that dimension - at least for some of the room - ought to have an effect either on the wavelength, or on the magnitude of the standing wave effect. I'm interested to learn why it doesn't work like that :)
 
Perhaps not totally moot but my experience from last L-shaped room was that they were not the main issue. Surprisingly minor.
My challenge is not that the shape of the room causes issues with the acoustics, but that the shape of the room makes all the calculations harder, and the online calculators don't help ;)
 
I was under the impression that these standing waves relate to one dimension of the room (as opposed to the volume of the room), and thought based on that that using panels that effectively change that dimension - at least for some of the room - ought to have an effect either on the wavelength, or on the magnitude of the standing wave effect. I'm interested to learn why it doesn't work like that :)
If you place rock wool in 1m thickness then it will have an effect. But I think you won't be doing that. For upper frequencies it's fine. For bass problems just get Dirac and be happy. :)

I agree that more graphical in-depth soft would be sweet.
 
@ohnonotagain it's back to front refractions that mater the most. Sure you will have refractions and from other walls and they can be problematic but to less extent. For first fundamental low end refraction the length of the room is most important and determine where it will be, following two are larger part harmonic propagations of that first one. So when you deal with first one you dealt and with most part of following two. As first one is low in low bass usually the acoustic panels and such don't help there. Big resonator bass trap or opposite firing sub's with phase switch do but that's expensive and not very suitable regarding the space it takes. So do the virtual bass area (as part of FIR correction) and PEQ for peaks. DSP correction ain't neither straight forward nor really cheap or easy to implement but it's still best thing to do and at least not space consuming and after all cheaper. I ain't saying that limited sound isolation is not useful, it is but in range of mids and highs.
 
My challenge is not that the shape of the room causes issues with the acoustics, but that the shape of the room makes all the calculations harder, and the online calculators don't help ;)
I have the same issue. But the measurement mic tells you more than a calculator.
 
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