Sources of background noise and their influence on vertebrate acoustic communication

Abstract

Many animals rely on long-range communication for species recognition, mate selection and territorial defense, but background noise from the environment can constrain their communication. Background noise from both biotic and abiotic sources is ubiquitous. In general, acoustic noise from abiotic sources, including anthropogenic noise, has energy mostly below 1 kHz. Arthropods tend to produce sounds in the 4-10 kHz range, while birds, amphibians and mammals generally have vocalizations with frequencies between 1 and 5 kHz. There are several ways that signalers could improve the efficiency of their acoustic signals to counteract the constraints of background noise. Signalers could make long-term and short-term signal adjustments to increase the detectability and discriminability of their signals. As predicted by signal detection theory adjustments can include increases in contrast between signals and noise, such as the intensity of the signal, the structure of the signal and an increase in signal redundancy. Our study reviews the sources of acoustic background noise, adjustments made by signalers to increase signal efficacy, and the influence of acoustic background noise on the evolution of acoustic communication in terrestrial vertebrate species.

Lombard effect onset times reveal the speed of vocal plasticity in a songbird

“…This omission from the literature is surprising given that many animals are often exposed to sudden changes in noise levels. In undeveloped natural habitats, falling branches, gusts of wind or the calls of conspecifics and heterospecifics are potential sources of intermittent high-amplitude noise bursts (Luther and Gentry, 2013). In urban areas, peaks in traffic during the morning and evening rush hours contribute to a daily fluctuation in noise levels, while short bursts of often very loud noise from sources such as car alarms, car horns, construction work or passing vehicles are common throughout the day (Warren et al, 2006;Luther and Gentry, 2013).…”

Gliding lizards use the position of the sun to enhance social display

“…Many studies have shown that animals can adjust aspects of acoustic communication (e.g. call frequency, amplitude and duration) to compensate for background noise [8,9]. Examples of adaptations for visual signals are relatively rare, but some bird species have been shown to orient or selectively display in sunlight to increase the conspicuousness of iridescent or short-wavelength-rich plumage [10][11][12].…”

Sounds of the city: The effects of urbanization and noise on mountain and black-capped chickadee communication.

“…Acoustic communication is a critical element involved in many different aspects of animal life, but especially so in avian systems, where it plays a key role in competition, mate attraction and reproduction (Collins, 2004). Because vocal communication is so important to avian fitness, human interference on signal transmission and perception is of paramount concern (Rabin & Greene, 2002;Patricelli & Blickley, 2006;Slabbekoom & den Boer-Visser, 2006;Warren et al, 2006;Luther & Gentry, 2013).…”