Low-frequency sound scatters less off tree trunks because wavelengths exceed trunk diameter.

Evidence

With only two exceptions, sites 3 and 6 in the summer, the decay rate increases (RT30 decreases) as frequency decreases. The physical reason for this behavior is illustrated in Fig. 9, where theoretical calculations of scattering from an infinitely long, rigid single cylinder are shown. — Donald G. Albert, Michelle E. Swearingen, Frank E. Perron, and David L. Carbee, Low Frequency Acoustic Pulse…, 99

Categorization

• DEFINE: Clarifies the physical scaling behind reverberation in forests: scattering strength tracks the ratio of wavelength to cylinder radius.