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Old 10th June 2016
Gear Maniac
soundthinker's Avatar

Still trying to formulate a real question, but looking at ETCs from Studio RES, Pressed Lizard, Blackbird C, and MyRoom mkII, I'm struck by how the mkII ETC slope, while longer, also goes significantly lower (dB) before leveling off. I may be misreading this because of the different scales used in the figures. It looks like almost 70 dB between the initial diffuse field and the noise floor.

I'm also intrigued by how even with slat gaps of only 6mm, there is still a 20dB drop from the initial sound to the diffuse field. I would have thought that with less porous absorber exposed, this would be higher. Is this more a function of the diffusers ability to absorb (scatter) energy? I know in the Blackbird design presentation floating around they make a big deal about how much the high prime 2d diffusers 'absorb'.

EDIT: I just found the .PDF and RPG uses the term 'attenuation' instead of absorb. And they state Blackbird's walls have an attenuation of 51dB.

Last edited by soundthinker; 10th June 2016 at 09:23 PM.. Reason: Found Blackbird pdf