What Is the Acoustic Barrier Sound Diffraction Calculator (Maekawa Model)?
The Acoustic Barrier Sound Diffraction Calculator determines noise attenuation achieved by solid walls, earth berms, and industrial noise barriers.
How Does the Acoustic Barrier Sound Diffraction Calculator (Maekawa Model) Work?
It computes acoustic path length difference over the barrier lip, derives the dimensionless Fresnel number N, and applies the Maekawa formula.
Acoustic Barrier Sound Diffraction Calculator (Maekawa Model) Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
Maekawa acoustic diffraction theory relating optical path length difference to edge wave shadow attenuation.
How to Use the Acoustic Barrier Sound Diffraction Calculator (Maekawa Model)
- Enter distance from noise source to barrier and barrier to receiver.
- Specify effective height of the wall top above the direct sightline.
- Choose acoustic evaluation frequency in Hz.
Step-by-Step Example Calculation
Highway Noise Wall at 500 Hz
Input Values:
Understanding Your Result
Insertion Loss (dB): Decibel reduction in sound level at the receiver.
Fresnel Number (N): Dimensionless parameter indicating diffraction severity.
Path Length Difference: Geometric detour sound must travel around the barrier top.
Factors That Affect the Result
- Positioning the barrier closer to either the source or the receiver maximizes path difference δ and noise reduction.
- Higher frequencies experience dramatically greater shadow attenuation.
When Should You Use This Calculator?
- Highway sound wall design, HVAC rooftop chiller screening, electrical substation noise abatement, and factory boundary walls.
Assumptions & Limitations
- Assumes an infinitely long straight barrier without significant end diffraction and quiet ambient wind conditions.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Based on Maekawa (1968) and FHWA Highway Noise Barrier Design Handbook.