Resistive absorbers only work where air particles move, which pushes them to high frequencies

Evidence

Clearly the larger the surface area available for interaction, the higher the friction and therefore the absorption. This means that porous materials, which consist of a large number of fibers per unit volume, such as high-density rock-wool or fiberglass and plush carpets, will tend to have a high-level absorption. This also explains why curtains that are draped to a fraction of their cloth area absorb more strongly than ones that are flat. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2046 (#expands, via linked claim)

If resistive absorption is to be useful, it must be at a distance from the room boundary—the portion of it that is adjacent to the boundary is doing nothing, and the effectiveness increases with distance from the boundary, or the thickness of the material, up to a maximum at the 1/4-wavelength distance where the particle velocity is maximum (Figure 4.21d). Look at Figure 4.19 and divide those wavelengths by four to get an idea of why resistive absorbers are not attractive solutions at low frequencies—even at a mid-bass frequency of 100 Hz the quarter-wavelength is 2.8 ft (0.86 m), which seriously intrudes on expensive real estate. — , Toole, Floyd E - Sound reproduction-…, 481 (#expands, via linked claim)

Categorization

• XREF: connects to: Higher frequencies produce higher particle velocities, improving porous absorber efficiency; Resistive absorbers are impractical at low frequencies because quarter-wavelengths are huge — , Toole, Floyd E - Sound reproduction-…, 481; Porous absorbers damp sound through velocity-induced frictional losses — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2046

Broader Connections

• Higher frequencies produce higher particle velocities, improving porous absorber efficiency #corroborates (0.95)
• Porous absorbers damp sound through velocity-induced frictional losses #expands (0.90) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2046
• Resistive absorbers are impractical at low frequencies because quarter-wavelengths are huge #expands (0.85) — , Toole, Floyd E - Sound reproduction-…, 481