Climate change is breaking Earth's beat

International audienceForests, deserts, rivers, and oceans are filled with animal vocalizations and geological sounds. We postulate that climate change is changing the Earth's natural acoustic fabric. In particular, we identify shifts in acoustic structure that all sound-sensitive organisms, marine and terrestrial, may experience. Only upstream solutions might mitigate these acoustic changes

Sonotope patterns within a mountain beech forest of Northern Italy: a methodological and empirical approach

According to the Sonotope Hypothesis, the heterogenous nature of the acoustically sensed, but not yet interpreted, environmental sounds (i.e., sonoscape) is created by the spatial and temporal conformation of sonic patches (sonotopes) as recently been described in a Mediterranean rural landscape. We investigated the Sonotope Hypothesis in a mountain beech forest of the Northern Apennines, Italy that is notoriously poor in soniferous species. Our aim was to test whether sonotopes were temporally distinct over seasonal and astronomical timeframes and spatially configured in relation to vegetation variables. We used the Acoustic Complexity Index (ACItf) to analyze the heterogeneity of sonic information gathered from an array of 11 sound recorders deployed within a lattice of eleven 4-ha hexagonal sample sites distributed throughout a 48-ha managed beech forest. We visualized and described the temporal patterns of ACItf between seasons (May–June and July–August 2021), across six astronomical periods (Night I, Morning Twilight, Morning, Afternoon, Evening Twilight, and Night II), and according to two aggregated frequency classes (≤2000 and >2000 Hz). We introduced Spectral Sonic Signature (SSS) calculated from the sequence of ACItf values along frequency bins as a descriptor of the dynamic production of sounds across spatial and temporal scales. We calculated Mean Spectral Dissimilarity to compare SSS values across temporal periods and between sample sites. We identified sonotopes by grouping similar SSS for each sample site generated from cluster analyses and visualized their spatial arrangements. Frequencies ≤2000 Hz (mainly geophonies from wind and rain) were more prevalent than frequencies >2000 Hz (mainly biophonies from songbirds). Despite there being no strong relationship to vegetation variables and minimal biophony and anthropophony, distinct sonotopes still emerged for every astronomical and seasonal period. This suggests that the sonoscape expresses distinct spatial and temporal sonotope configurations associated with the temporal and spatial patterns of geophysical events that generate geophonies with minimal animal or anthropogenic occurrences. A new strategy based on the reintroduction of indigenous trees and shrubs in managed clearings should be considered for enhancing local biodiversity conservation along with ecoacoustic monitoring based on the Sonotope Hypothesis

THE SOUNDSCAPE APPROACH FOR THE ASSESSMENT AND CONSERVATION OF MEDITERRANEAN LANDSCAPES: PRINCIPLES AND CASE STUDIES

Abstract The fine-grained mosaic of natural and human-modified patches that characterizes the Mediterranean region has created a multifaceted system that is difficult to investigate using traditional ecological techniques. In this context, sounds have been found to be the optimum model to provide indirect and timely information about the state of ecosystems. The sonic nature of the environment (the soundscape) represents an important component of the landscape, and the new discipline of soundscape ecology has recently been shown to have appropriate tools for investigating the complexity of the environment. In the last decade, technological advances in the acoustic field have led researchers to carry out wide-scale and long-term ecological research using new and efficient tools, such as digital low cost sound recorders, and autonomous software and metrics. Particularly in the Mediterranean region, where land transformation occurs at a very rapid rate, soundscape analysis may represent an efficient tool with which to:1) track transformations in the community balance, 2) indicate the most acoustically complex parts (bioacoustic hotspots) of the land mosaic, 3) prevent environmental degradation, and 4) decide whether protection or restoration actions are most appropriate. Conserving the quality of Mediterranean sounds means preserving the natural dynamics of its animal populations and also involves maintaining the cultural heritage, human identity, and the spiritual values of the area

Editorial: Advances in ecoacoustics

Presentation of a Special Issue on ecoacoustics with analysis of the contributions and of the current knowledge gaps

Relationships of sound pressure and particle velocity during pile driving in a flooded dock

Underwater sound is characterized by two different components, directional particle motion and scalar pressure waves. Here, we studied sound pressure and particle motion during experimental pile driving in a confined industrial-sized shipbuilding dock. The pile driving noise was generated by a 200 kg hammer striking a 7.5m steel pile. Noise data were collected using a hydrophone and a 3-axis accelerometer along 27 equally spaced locations. The results show that the relationship between the two components is approximately linear, as theory suggests, but the recorded values of particle velocity are generally larger than expected, particularly for the z-axis velocity which is shown to have a magnitude of 1 to 10 times (average 3.5) that of the theoretical velocity for a plane wave at the same sound pressure.Moreover, sound pressure and particle motion showed a different frequency distribution. For sound pressure, a shallow water cut-off frequency below approximately 400 Hz was observed in the power spectrum, which was not observed for particle velocity. This could be due to ground roll waves, but also wind induced waves and vibration on the cable could cause an increase in the low frequency vertical velocities.</p

Sonotopes reveal dynamic spatio-temporal patterns in a rural landscape of Northern Italy

A sonotope is characterized as a sonic patch that forms a hierarchical link between a finer, local scaled acoustic community and the coarser landscape scaled sonoscape. Unfortunately, the concept of sonotopes has yet to be empirically supported. We tested the hypothesis that a spatially explicit sample of sonic information from a heterogeneous landscape would exhibit spatially unique sonotopes with distinct spatio-temporal patterns and acoustic communities. We used the Acoustic Complexity Index (ACItf) to analyze sonic information (WAV) gathered from an array of 10 sound recorders deployed within a lattice of 10, 4-ha hexagonal sample sites distributed evenly throughout a 48-ha undivided heterogeneous landscape in Northern Italy. We examined the temporal patterns of sonic activity (ACItf) between seasons (March – July and August – November 2021) and across five astronomical periods of a 24-h day (Night I, Morning Twilight, Day, Evening Twilight, and Night II). We used cluster analyses to identify sonotopes from groupings of similar ACItf values for each sample site and visualized the spatial arrangements of sonotopes throughout our study area between seasons and among astronomical periods. Sonic activity from bird biophonies increased in March – July during the Day but in August – November greater sonic activity shifted to crepuscular and nocturnal periods with the biophonies from crickets. Sonotopes exhibited spatially unique, dynamic arrangements of patch size and placement depending on the season and astronomical period. We discuss how acoustic communities and continuous geophonies play a role in the arrangement of sonotopes and their relation to the sonoscape

Determining temporal sampling schemes for passive acoustic studies in different tropical ecosystems

Among different approaches to exploring and describing the ecological complexity of natural environments, soundscape analyses have recently provided useful proxies for understanding and interpreting dynamic patterns and processes in a landscape. Nevertheless, the study of soundscapes remains a new field with no internationally accepted protocols. This work provides the first guidelines for monitoring soundscapes in three different tropical areas, specifically located in the Atlantic Forest, Rupestrian fields, and the Cerrado (Brazil). Each area was investigated using three autonomous devices recording for six entire days during a period of 15 days in both the wet and dry seasons. The recordings were processed via a specific acoustic index and successively subsampled in different ways to determine the degree of information loss when reducing the number of minutes of recording used in the analyses. We describe for the first time the temporal and spectral soundscape features of three tropical environments. We test diverse programming routines to describe the costs and the benefits of different sampling designs, considering the pressing issue of storing and analyzing extensive data sets generated by passive acoustic monitoring. Schedule 5 (recording one minute of every five) appeared to retain most of the information contained in the continuous recordings from all the study areas. Less dense recording schedules produced a similar level of information only in specific portions of the day. Substantial sampling protocols such as those presented here will be useful to researchers and wildlife managers, as they will reduce time- and resource-consuming analyses, whilst still achieving reliable results