Fan Noise

Overview

Engineering reference data for Fan Noise in acoustics.

Key Formulas

Speed of Sound

$c = \sqrt{\gamma R T}$

Speed of sound in an ideal gas.

Sound Level

$L = 10 \log_{10}(I/I_0)$

Decibel level.

Wavelength

$\lambda = c / f$

Wavelength = speed / frequency.

Variables

Symbol	Description	Unit
$c$	Speed of sound	m/s
$L$	Sound level	dB
$\lambda$	Wavelength	m
$f$	Frequency	Hz

Octave Band Correction Factors

To calculate sound power levels in specific octave bands, add these correction factors to the overall sound power level.

Discharge Velocity Guidelines for Quiet Operation

To minimize noise generation, the discharge air velocity from fans should not exceed the following limits:

ACMA Certified Fan Sound Levels (Example)

The following table provides an example of certified sound-power levels for different fan models across octave bands.

Unit Conversion Note: The velocity limits can be converted using: 1 m/s = 3.6 km/h = 196.85 ft/min = 2.237 mph.

Interactive Charts

References

• Original Source