Objects near two-thirds wavelength produce interference because reflection and diffraction combine

Evidence

In addition to the scattering effects, interference effects happen when the scattering object is about two thirds of a wavelength (2/3 λ) in size. This is because at this frequency, both reflection from and diffraction around the object is occurring. In this situation, the waves on the two sides of the object can influence or interact with each other. This results in enhanced reflection from or diffraction around the object at particular wavelengths. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 437

Categorization

• corroborated: 2 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 437