Possibly foolish question: is it not possible to derive anechoic FR from in-room FR?

[Sashoir]

FFTs and signal processing are topics I've not even been passingly familiar with for a few decades, but: if one has a "true" FR for a loudspeaker from preferred (anechoic, NFS, what have you) meadurement, and a measured response from a certain placement in a certain space of the same loudspeaker, is it not possibly to deconvolve/invert to get the space's transfer function and then apply this deconvolution to other loudspeakers measured with that placement in that space to get pseudo-anechoic measurements? Is that computationally too difficult, or is it more that the variability between enclosures, driver positions, and sensitivity to these boundary conditions is too great for such a constructed measurement to be useful?
Thank you in advance for illuminating my ignorance.
Best,
S

 

[whazzup]

I do not understand the technical aspects, but I believe that's what the Klippel system is doing. Measure in-room and 'work backwards' to remove room influence. How they're doing it.... guess that's their 'secret sauce'?

 

[abdo123]

I do not understand the technical aspects, but I believe that's what the Klippel system is doing. Measure in-room and 'work backwards' to remove room influence. How they're doing it.... guess that's their 'secret sauce'?

not really. it's far from that.

 

[Sashoir]

Thank you! I had assumed instead (because of all the robotics) that it was "just" taking a zillion ultra near field measurements and comparing them to "remove" the echoes.

 

[PierreV]

@whazzup @NTK has provided a lot of insight about how to tackle the problem

DIY 3D Speaker Scanner - the Mathematics and Everything Else

Let me get this out of the way first. Yes, my goal is to figure out how to build a 3D speaker scanner similar to Klippel's. Of course the first step is to figure out the theories. In my post back in August, I wrote that I knew next to nothing about the mathematics of acoustics. I also wrote...

www.audiosciencereview.com

@Sashoir I also have some familiarity with deconvolution techniques (more in the image processing area) and my gut feeling says it won't work for both of the reasons you mentioned (and ambiguous solutions if it did work).

 

[abdo123]

FFTs and signal processing are topics I've not even been passingly familiar with for a few decades, but: if one has a "true" FR for a loudspeaker from preferred (anechoic, NFS, what have you) meadurement, and a measured response from a certain placement in a certain space of the same loudspeaker, is it not possibly to deconvolve/invert to get the space's transfer function and then apply this deconvolution to other loudspeakers measured with that placement in that space to get pseudo-anechoic measurements? Is that computationally too difficult, or is it more that the variability between enclosures, driver positions, and sensitivity to these boundary conditions is too great for such a constructed measurement to be useful?
Thank you in advance for illuminating my ignorance.
Best,
S

The difficulty is that speakers of different sizes, heck, even from different production patches will radiate differently and you could very well change the location of the speaker milimeters or centimeters each time you measure it or measure others and basically it makes this sort of work impossible without some sort of anechoic range (usually above 100 Hz) and some robot making sure the angles are all the same.

 

[Sashoir]

Thanks everyone. I knew there'd be no free lunch: I just couldn't find the bill