Vegetation attenuation thresholds differ measurably across cover types and soil states
Evidence
In an important experiment Aylor (1971) measured the transmission of random noise through dense corn, a dense hemlock plantation, an open pine stand, a dense hardwood brush stand, and in an overcultivated soil. In particular the relationship between attenuation and frequency can be modeled and the model applied to all other typologies of vegetation. Each cover has a different threshold to excess attenuation: for example, corn 6 dB/100 ft for each doubling of frequency between 500 and 4,000 Hz. The stems of hemlock, pine, and brush have an excess of attenuation of about 5 dB/100 ft at 4,000 Hz. Bare ground has an attenuation effect at frequencies between 200 and 1,000 Hz, depending on the amount of air in the soil (permeability). Tilling soil reduces the frequency of peak attenuation from 700 to 350 Hz. — Almo Farina, Soundscape Ecology, 331
Categorization
- XREF: This is the Aylor study that is one of the core acoustic papers the whole methods index plugs into; it gives concrete per-cover dB figures. — connects to: Leaf veins filter vibratory signals toward the leaf apex as low-pass channels — Almo Farina, Soundscape Ecology: Principles,…, 332; Excess attenuation increases with frequency in vegetated habitats — Almo Farina, Soundscape Ecology: Principles,…, 418; Vegetation substrate type shapes the spectral character of wind noise — Almo Farina, Soundscape Ecology: Principles,…, 1255 (+6 more)
Broader Connections
- Excess attenuation increases with frequency in vegetated habitats
#expands(0.88) — Almo Farina, Soundscape Ecology, 418 - Ground and vegetation attenuate noise in complementary frequency ranges.
#expands(0.86) — Donald Aylor, Noise Reduction by Vegetation and Ground, 122 - Vegetation substrate type shapes the spectral character of wind noise
#expands(0.85) — Almo Farina, Soundscape Ecology, 1255 - Leaf width and canopy leaf area drive sound scattering in dense vegetation
#expands(0.84) — Almo Farina, Soundscape Ecology, 321 - Primary rainforest and forest edge habitats show sharply different spectral noise profiles
#exemplifies(0.82) — Almo Farina, Soundscape Ecology, 335 - Each habitat has a distinctive ambient noise spectral profile
#exemplifies(0.80) — Almo Farina, Soundscape Ecology, 1256 - Prior noise studies conflicted after omitting ground attenuation as a variable.
#complicates(0.78) — Donald Aylor, Noise Reduction by Vegetation and Ground, 4 - Each degradation aspect traces to specific physical mechanisms in habitat
#expands(0.72) — Almo Farina, Soundscape Ecology, 663