ASA/ANSI S12.18-1994 (R2023): Sound Pressure Level
Sound pressure is the difference between the pressure from a sound wave and the ambient pressure of what the sound is traveling through (usually air)….
ANSI/AMCA 320-23: Sound Testing Of Fans
A slower fan speed does not produce a lower sound level. So, what determines a silent fan? The lowest fan sound level during operation is…