Whether a surface reflects or scatters waves depends on roughness relative to wavelength

Evidence

Sound that is incident on an object is not just diffracted around it—some of the incident energy will be reflected, or scattered, from the side facing the incident wave, as shown in Figure 1.47. As in the case of diffraction, it is the size of the object with respect to the wavelength that determines how much and in what way the energy is scattered. When the object is large with respect to the wavelength, most of the sound incident on the object is scattered according to the laws of reflection, and there is very little spreading or diffraction of the reflected wave, as shown in Figure 1.48. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 435 (#corroborates, via linked claim)

Categorization

Category: Causal Relationships

Related

• Flat surfaces reflect low-frequency sound specularly but scatter high-frequency sound (similarity 0.94)
• Acoustic diffusion needs surface bumps sized between an eighth and a half wavelength (similarity 0.89)
• Sound bends around obstacles through a process called diffraction (similarity 0.87)
• How bumps reflect sound depends on bump height relative to wavelength. (similarity 0.87)
• Whether a surface reflects specularly or diffusely depends on wavelength, not polish (similarity 0.87)
• Reflection from a bumpy surface depends on bump height relative to wavelength. (similarity 0.87)
• Reflection and diffraction of sound both depend on object size relative to wavelength (similarity 0.86)
• Element-based acoustic models scale poorly as wavelength shortens (similarity 0.85)
• Sound scatters or diffracts around loudspeakers based on wavelength relative to size (similarity 0.85)
• Regularly spaced surface bumps diffuse sound only at specific frequencies (similarity 0.83)
• A piston’s radiation efficiency depends on size relative to wavelength, not absolute size (similarity 0.83)
• Acoustic wavelength size relative to objects governs how sound interacts with them (similarity 0.83)
• Any change in surface reflectivity, not just bumps, causes sound diffusion (similarity 0.83)
• Reflected sound fields dominate at low frequencies for almost all sources (similarity 0.82)
• Free-field radiation requires the source to be far from reflecting surfaces (similarity 0.82)

Broader Connections

• How bumps reflect sound depends on bump height relative to wavelength. #expands (0.92)
• Flat surfaces reflect low-frequency sound specularly but scatter high-frequency sound #exemplifies (0.90)
• Reflection and diffraction of sound both depend on object size relative to wavelength #corroborates (0.85) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 435
• Radiation directivity depends on wavelength relative to source size #corroborates (0.80)