Anechoic Chamber

The acoustic noise is measured in an semianechoic chamber by means of B & K precision integrating sound level meter with back ground noise level below 20dBA.

The fan is running in non-resistant air with microphone at a distance of one meter from the fan intake.

Sound pressure level (SPL) which is environmentally dependent and sound power level (PWL) are defined as SPL = 20 log10 P/Pref

SPL = 20 log10 P/Pref

PWL = 10 log10 W/Wref

P =Pressure

Pref= A reference pressure

W =Acoustic power of the source

Wref =An acoustic reference power

Fan noise data is usually plotted as Sound Power Level against the octave frequency bands.

The measurement standard is according to : CNS 8753(which is comparable to DIN 45365)