What Is the Sound Pressure Level (SPL) Distance Attenuation Calculator?
Sound pressure level distance attenuation quantifies how acoustic intensity dissipates as sound waves expand away from a source.
How Does the Sound Pressure Level (SPL) Distance Attenuation Calculator Work?
Applies geometric inverse-square spreading law (20*log10 of distance ratio) to calculate decibel reduction.
Sound Pressure Level (SPL) Distance Attenuation Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
L_{p2} = L_{p1} - 20 log_{10}left( rac{r_2}{r_1}
ight), quad L_w approx L_p + 20log_{10}(r) + 11
Geometric divergence sound decay from a point source in spherical free field.
How to Use the Sound Pressure Level (SPL) Distance Attenuation Calculator
- Input known SPL at a reference distance and the target distance to evaluate receiver exposure.
Step-by-Step Example Calculation
Outdoor Industrial Machinery Noise
Input Values:
splReferenceDb:85
distanceReferenceM:1
distanceTargetM:15
Worked Steps: Attenuates by 23.5 dB to an SPL of 61.5 dB at 15 meters; sound power Lw = 96.0 dB.
Understanding Your Result
Provides target SPL and total geometric attenuation loss in decibels.
Factors That Affect the Result
- Atmospheric air absorption (humidity/temperature) and ground reflection barriers introduce additional damping at high frequencies.
When Should You Use This Calculator?
- Environmental noise impact assessments, audio concert loudspeaker arrays, and occupational OSHA safety compliance.
Assumptions & Limitations
- Assumes point source in an obstacle-free free-field environment without indoor boundary reverberation.
Frequently Asked Questions
Calculation Accuracy & Reference Note
ISO 9613-2 acoustic propagation standard geometric divergence.