Sound diffraction arises from gradual pressure decay, not abrupt wave cutoff

Evidence

Diffraction occurs because the variations in air pressure, due to the com­ pressions and rarefactions in the sound wave, cannot go abruptly to zero after passing the edge of an object. This is because there is interaction between the adjacent molecules that are propagating the wave. In order to allow the compressions and rarefactions to die out gracefully in the bound­ ary between the wave and the shadow, there must be a region in which part of the propagating wave changes direction, and it is this bent part of the wave that forms the diffracted component. — David Howard, Jamie Angus, coustics and Psychoacoustics, 417

Categorization

Category: Causal Relationships

• DEFINE: Explains the mechanism that makes diffraction occur, clarifying the physics behind the term.

Related

• Sound bends around obstacles because pressure changes cannot end abruptly at shadow boundaries (similarity 0.96)
• Diffraction arises because air-pressure waves cannot abruptly end at an edge (similarity 0.95)
• Sound bends around obstacles through a process called diffraction (similarity 0.89)
• Lower frequencies diffract more around obstacles than higher frequencies do (similarity 0.86)
• More diffraction occurs for longer-wavelength, lower-frequency sound (similarity 0.85)
• Diffraction occurs around solid objects as well as through openings. (similarity 0.84)
• Sound diffraction arises when a wavefront’s edge acts as a secondary source (similarity 0.84)
• A sound wave’s pressure component arises from the force driving molecular displacement. (similarity 0.84)
• Downwind sound is bent downward and waveguides along the ground, gaining intensity (similarity 0.83)
• Wind gradients refract sound toward slow regions and extend its range (similarity 0.82)
• Atmospheric physics creates striking asymmetries in how sound travels (similarity 0.82)
• Wind speed gradients, not wind itself, refract sound and break reciprocity (similarity 0.81)
• Flat surfaces reflect low-frequency sound specularly but scatter high-frequency sound (similarity 0.81)
• Sound bends like light because temperature changes its speed. (similarity 0.81)
• Sound diffracts strongly only when wavelengths exceed opening size (similarity 0.81)

Broader Connections

• Molecular interaction prevents sound pressure from cutting off sharply at edges #corroborates (0.90) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 422
• Sound bends around obstacles through a process called diffraction #expands (0.80) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 421