Sound diffraction arises when a wavefront’s edge acts as a secondary source

Evidence

When a wave interacts with a geometrical discontinuity like a boundary, scattering occurs. Reflection can be interpreted as the simple case of backscattering from a boundary layer. More general scattering in acoustics is called diffraction. It is a complex phenomenon that is difficult to analyse and model. A solid object or its edge acts as a kind of secondary source. Huygens’ principle interprets a wavefront as a set of directed secondary sources that maintains a regular wave propagation. A geometrical discontinuity disturbs this propagation and makes diffraction the secondary observable source. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 259

Categorization

• DEFINE: Clarifies reflection as backscattering and diffraction as scattering from edges and boundaries.