194 Theoretical limit for a sound wave at 1 atmosphere environmental pressure; pressure waves with a greater intensity behave as shock waves.
188 Space Shuttle liftoff as heard from launch tower (less than 100 feet) [1] [2].
180 Krakatoa volcano explosion at 1 mile (1.6 km) in air [3]
160 M1 Garand being fired at 1 meter (3 ft); Space Shuttle liftoff as heard from launch pad perimeter (approx. 1500 feet) [4] [5].
150 Jet engine at 30 m (100 ft)
140 Low Calibre Rifle being fired at 1m (3 ft); the engine of a Formula One car at 1 meter (3 ft)
130 Threshold of pain; civil defense siren at 100 ft (30 m)
120 Space Shuttle from three mile mark, closest one can view launch.[6] [7]. Train horn at 1 m (3 ft). Many foghorns produce around this volume.
120 Concert of music, louder if indoors.
110 Football stadium during kickoff at 50 yard line; chainsaw at 1 m (3 ft)
100 Jackhammer at 2 m (7 ft); inside discothèque
90 Loud factory, heavy truck at 1 m (3 ft), kitchen blender
80 Vacuum cleaner at 1 m (3 ft), curbside of busy street, PLVI of city
70 Busy traffic at 5 m (16 ft)
60 Office or restaurant inside
50 Quiet restaurant inside
40 Residential area at night
30 Theatre, no talking
20 Whispering
10 Human breathing at 3 m (10 ft)
0 Threshold of human hearing (with healthy ears); sound of a mosquito flying 3 m (10 ft) away
A 3 dB increase in the level of continuous noise doubles the sound power, however experimentation has determined that the response of the human ear results in a perceived doubling of loudness for approximately every 10 dB increase (part of Stevens' power law).
I think thats what ur after.
More importantly, you are looking for a HSF that is quiet at HIGH RPM. This can be very difficult to find. You are best off 'making your own hsf'.
I believe the Tuniq Tower is very good. Get rid of those 120mm fans, and get the biggest fan u can fit in your case, 200mm if possble. Use two, and build a intake and outtake venturi to channel the air. This will achive your goal of of quite, while maintaining good temps.
Bottom line... u cannot get low noise from high RPM
L8RR