Velocity of the air flowing through the current duct, and causes the pressure drop that produces the calculated sound. To avoid that the channels will resonate which in turn would generate more noise than the speed should in a circular duct not exceed about 11 m / s while in a rectangular, the rate should be less than about 7 m / s.
Refers to the diameter of the circular duct. Circular duct is the main option in the calculations and priorities into account before the rectangular duct.
The width of the rectangular duct.
Does the height of the current rectangular duct.
Shows how much the sound generated in a normal sheet metal duct. The calculation is an approximation of the more exact values used ljudalstringsdiagram from the current channel manufacturer.
As the air flows in a duct, it causes friction which in turn creates noise.