Pure-tone notes exploit reverberation to travel farther in dense forest

Evidence

Narrow-frequency bandwidth notes (NFB) are pure tones that do not have great changes in frequency; these tones are emitted by birds that live in dense forests and differ from frequency-modulated notes. These notes benefit from reverberation, allowing the transmission of a longer and louder signal as demonstrated by playback experiments conducted by Slabbekoorn et al. (2002) on the green hylia (Hylia prasina), a bush warbler passerine (family Cettiidae) living in dense forests of tropical Africa. Its song is quite simple, composed of two successive NFB.

Longer notes produced a stronger behavioral response, demonstrating that reverberation can improve signal transmission when the signal design is adapted as in NFBs.

— Almo Farina, Soundscape Ecology, 432

Categorization

• DEFINE: Defines NFB (narrow-frequency-bandwidth pure tones) and the mechanism by which reverberation aids their transmission in dense forest.
• XREF: connects to: Dense multi-layered jungle vegetation makes hearing more efficient than sight — Almo Farina, Soundscape Ecology: Principles,…, 341; Forest birds favor pure tones around 2,200 Hz where attenuation is lowest — Almo Farina, Soundscape Ecology: Principles,…, 422; Gothic cathedral acoustics may echo the reverberation of primeval evergreen forests — Schafer, Murray R, The Soundscape- Our Sonic Environment…, 83 (+1 more)

Broader Connections

• Gothic cathedral acoustics may echo the reverberation of primeval evergreen forests #responds-to (0.75) — Schafer, Murray R, The Soundscape- Our Sonic Environment…, 83