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NFS, Spinoramas, and non vertical/horizontal off-axis response

Mario Sanchez

Jan 11, 2021
So, if my understanding is not mistaken, NFS can scan for the entire sphere across which the speaker is radiating energy and compute the far-field response at any point on that sphere, while the CTA2034 graph generated from the NFS scan uses *only* the 360 degrees horizontal and vertical responses (like spinorama)? Please kindly correct me if I'm mistaken.
I know Amir sometimes take advantage of this full-sphere scan and posts balloon plots for some speakers at certain problematic frequencies using the NFS's scan results, but is there any way to consistently incorporate these non horizontal/vertical measurements into the existing measurement suite (DI curves, for example) ?
This inclusion of non-horizontal and vertical measurements probably won't change results by much, but I think it would be nice if the extra data points are put to use.
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Major Contributor
Forum Donor
Aug 11, 2019
US East
You are correct that the NFS can compute the speaker response at any arbitrary location in space.

The CTA2034 method only uses measurements in the horizontal and vertical orbits for all calculations. The reason is that almost all listening rooms have vertical walls and horizontal floor, and usually a horizontal ceiling. The reflected sound we hear is therefore mostly originated from the horizonal and vertical outputs. Those sound radiation that came from other angles required many more bounces to reach the listener, and is much more attenuated in comparison. That is the reason only the horizontal and vertical orbits are needed, the other angles contribute relatively little.
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