Enter the sound power level of the fan and the distance from the fan into the calculator to determine the sound pressure level at that point.
Fan Noise Formula
The following formula is used to calculate the sound pressure level of a fan at a certain distance:
Lp = Lw - 20 * log10(D) - 11
Variables:
- Lp is the sound pressure level at the listener’s position (dB)
- Lw is the sound power level of the fan (dB)
- D is the distance from the fan to the listener’s position (meters)
To calculate the sound pressure level, subtract the product of 20 times the logarithm (base 10) of the distance from the fan’s sound power level and then subtract 11 dB for the directivity of the fan.
What is Fan Noise?
Fan noise is the sound pressure generated by a fan as it operates. It is a combination of sounds produced by the motor, the movement of air, and the fan blades cutting through the air. The sound power level (Lw) is a measure of the total sound energy emitted by the fan, while the sound pressure level (Lp) is the sound intensity at a specific distance from the fan. Understanding fan noise levels is important for designing quiet workspaces and living environments.
How to Calculate Fan Noise?
The following steps outline how to calculate the Fan Noise.
- First, determine the sound power level of the fan (Lw) in decibels (dB).
- Next, determine the distance from the fan to the listener’s position (D) in meters.
- Next, gather the formula from above = Lp = Lw – 20 * log10(D) – 11.
- Finally, calculate the Sound Pressure Level (Lp) in decibels (dB).
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
Sound power level of the fan (Lw) = 90 dB
Distance from the fan (D) = 5 meters
