Strutt|Input Data|Empirical|Fan inserts sound power levels into the active row of the worksheet.
The total sound power has been calculated using the formula:
`L_W = 20log_10 P + 10log_10 V + 40`
`P` is the fan total static pressure, Pa
`V` is the fan volume, m3/s
Octave band sound power levels have then been calculated by adding spectral corrections as follows:
|Fan Type||63 Hz||125 Hz||250 Hz||500 Hz||1 kHz||2 kHz||4 kHz|
Blade-pass frequency is calculated is calculated as: BPF = (rpm*number of impeller blades)/60. With this option selected, 5 dB is added to the octave band containing the BPF and 3 dB is added to the octave band containing first harmonic.