Which specific Noiseblockers? The SX-1's were tested back when we first released the PA Series and were found to be one of the worst performers with insufficient air pressure.
Unsure - it was a while ago and they were sent to Australia for the testing and remained there... basically, they weren't included in the testing linked to in the OP because they were already known to perform worse than the fans that were tested when it came to cfm vs noise. (IE: other fans moved more air with less noise).