Climate shapes signal propagation through humidity and temperature-dependent sound absorption

Evidence

Signaling systems may diverge along an ecological gradient, and this has great implications in speciation and diversification. Several studies have focused on environmental drivers such as vegetation but little attention has been devoted, as already stressed, on the effects of climatic changes on signal transmission (Snell- Rood 2012). In fact, climate is important for sound propagation because humidity, temperature, and air turbulence largely depend on climatic conditions. It is well known that a signal decreases in intensity because of spherical spreading, but atmospheric absorption represents an important proxy. This sound absorption increases with the frequency of sound but it varies also for temperature and relative humidity. So, signaling systems are conditioned by climate. … Snell-Rood (2012) reports that although an avian vocalization may have an absorption of only 0.1 dB/m, this effect may be 10 dB on a surface of 1 ha of territory. It remains unclear if the value of absorption between species is the same within the species, and the effect of climate change on the evolution of acoustic signals remains to be investigated. This point is of extreme importance. We have often observed how seasonality favors or can affect signal transmission, expressed as a useful time to sing. It is well documented that during bad weather conditions, song activity is significantly depressed. — Almo Farina, Soundscape Ecology, 756

Categorization

• XREF: connects to: Global warming has shifted frog calling seasons earlier by ten to thirteen days — Almo Farina, Soundscape Ecology: Principles,…, 294; Climate change alters how far animal acoustic signals travel. — Bernie Krause and Almo Farina, Using Ecoacoustic Methods to Survey the…, 32; Wind refraction and humidity structure alter sound propagation in air — Almo Farina, Soundscape Ecology: Principles,…, 1895 (+6 more)

Broader Connections

• Wind refraction and humidity structure alter sound propagation in air #expands (0.90) — Almo Farina, Soundscape Ecology, 1895
• Wind gradients refract sound toward slow regions and extend its range #expands (0.85)
• Atmospheric physics creates striking asymmetries in how sound travels #expands (0.80)
• Wind gradients bend sound waves and explain downwind audibility #expands (0.80)
• Sound propagation depends on interactions with objects and the medium #expands (0.75) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 322