Assessing the effect of sound file compression and background noise on measures of acoustic signal structure

Araya‐Salas, Marcelo; Smith‐Vidaurre, Grace; Webster, Michael S.

doi:10.1080/09524622.2017.1396498

Cited by 47 publications

(43 citation statements)

References 31 publications

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“…However, we believe that the magnitude of this bias is not strong enough to compromise our comparisons since we expect larger spectral divergence between populations than the mean frequency measurement error of 86 Hz caused by lossy compression (Araya‐Salas et al . ).…”

Section: Methodsmentioning

confidence: 97%

Vocal divergence between two disjunct populations of Giant Antshrike (Batara cinerea) is related to environmental conditions

Sementili‐Cardoso

Donatelli

2018

Austral Ecology

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Variation in the avian vocal signals emitted may have a significant impact on species evolution. Vocal divergence in suboscine species like Giant Antshrike (Batara cinerea) may be associated with selective adaptation, since learning has little influence on vocal development and variation in acoustic structure cannot be attributed to learning deviation. Consequently, tracheophone suboscine species are ideal subjects to explore vocal variation, since cultural evolution does not seem to influence vocal variation in this group. Environmental conditions may determine the selection of vocal features because acoustic transmission could be attenuated under certain conditions of temperature, humidity and vegetation cover. Here, we examined vocalizations of Giant Antshrike and assessed possible acoustic variations between two disjunct groups (Andean and Atlantic), correlating the differences to the environmental structure. Univariate and multivariate analysis show temporal and spectral differences between both groups. Andean individuals produce vocalizations with longer duration, faster trill rates, shorter syllable duration and higher frequencies. Environmental features are different between the two populations, and they are correlated to the acoustic structure of vocalizations. Temporal variations arise directly from climatic influence, while spectral divergence could be a secondary effect of morphological adaptation to habitat structure.

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Section: Methodsmentioning

confidence: 97%

Vocal divergence between two disjunct populations of Giant Antshrike (Batara cinerea) is related to environmental conditions

Sementili‐Cardoso

Donatelli

2018

Austral Ecology

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“…We quantified 12 fine structural characteristics of the songs of Olive Sparrows that described the frequency and temporal traits of songs. We included four measurements based on the spectrum (Araya‐Salas and Smith‐Vidaurre , Sueur , Araya‐Salas et al ), including (1) mean frequency (the average of the frequencies in the signal weighted by their amplitude), (2) standard deviation of the mean frequency, (3) first quartile frequency (based on the power spectrum, the smallest discrete frequency in kHz where the summed energy under the frequency value has to exceed 25% of the total energy), and (4) third quartile frequency (based on the power spectrum, the smallest discrete frequency in kHz where the summed energy under the frequency value has to exceed 75% of the total energy).…”

Section: Methodsmentioning

confidence: 99%

Geographic variation and divergence of songs in the Olive Sparrow species complex

2020

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Phenotypic traits such as songs are important in species recognition. Variation in acoustic traits can form barriers to gene flow and promote speciation. Therefore, understanding song divergence is crucial in groups with controversial taxonomy such as Olive Sparrows (Arremonops rufivirgatus), a widespread Neotropical species of songbird with multiple allopatric populations. Taxonomic authorities disagree on the number of Olive Sparrow subspecies, placing them into either two or three main groups. These groups may represent separate species based on morphological traits, but trait divergence within the complex has not been examined. We studied geographic variation in the characteristics of the songs of Olive Sparrows at two geographical levels: among three proposed groups and among five allopatric populations. In a second analysis, we evaluated the strength of acoustic divergence within the complex by comparing acoustic distances among groups and allopatric populations of Olive Sparrows with the acoustic distance among three recognized species in the genus Arremonops. We analyzed 802 songs from 174 individuals across 81 locations and measured 12 variables to describe the fine structural characteristics of the songs of Olive Sparrows, Green‐backed Sparrows (A. chloronotus), Black‐striped Sparrows (A. conirostris), and Tocuyo Sparrows (A. tocuyensis). We found significant acoustic variation in the Olive Sparrow complex at both geographical levels. Our divergence analysis also revealed that vocal divergence within the complex is similar to or greater than that found between recognized species in the genus. Together, these results suggest that acoustic diversity within the Olive Sparrow complex probably originated by isolation in tandem with selective and/or non‐selective factors.

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“…Xeno‐canto provide recordings in mp3 format, which we converted into wav format using Audacity (Audacity Team ) as required for subsequent analyses. Compression to mp3 format does not appear to bias estimated parameters, but may affect the precision of certain measurements (Araya‐Salas et al ); however, by sampling across a wide range of taxa we hope to accommodate for any potential effect. We did not choose recordings based on sampling rate, bitrate, or number of mp3 channels.…”

Section: Methodsmentioning

confidence: 99%

“…We analyzed the recordings using a combination of approaches. First, we analyzed recordings in the statistical program R (R Core Team) using the package ‘warbleR’ (Araya‐Salas and Smith‐Vidaurre ), which allowed for efficient measuring of acoustic parameters, quantifying by default 29 different audio parameters. From these 29 parameters, we only retained those four which had previously been suggested to describe audio complexity: spectral entropy (complexity of the audio elements, Tchernichovski et al ), spectral flatness (distribution of energy across spectral bands, Tachibana et al ), modulation index (accumulated absolute difference between adjacent measurements of fundamental frequencies divided by the frequency range, Nottebohm ) and bandwidth (maximum – minimum frequency, Seddon et al ).…”

Section: Methodsmentioning

confidence: 99%

Identifying ecological drivers of interspecific variation in song complexity in songbirds (Passeriformes, Passeri)

Crouch

Mason‐Gamer

2019

Journal of Avian Biology

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A diversity of selective pressures and stochastic processes have likely created substantial variation in song structure, creating difficulties in quantifying the influence of specific ecological factors. This problem is further compounded by differences in study taxa and methods of data analysis between studies. Large comparative studies offer the potential to mitigate some of these methodological difficulties by maximizing the power of statistical analyses and minimizing the probability of misidentifying the magnitude and direction of relationships between independent and dependent variables. In this study, we quantified song complexity for 367 species of globally distributed songbirds (Passeriformes, Passeri). We quantified eight individual acoustic variables that have previously been linked to audio complexity which we analyzed independently, and after applying multivariate statistics to the variables. We used Bayesian linear mixed effect models to test multiple hypotheses regarding song complexity: that it should be greater in open habitats, in migratory species, for sexually monomorphic species, at higher latitudes and altitudes, and that it should co‐vary with clutch size characteristics. Our results challenge perceptions of the effect of habitat structure on song complexity; for instance, counter to expectation, we found songs in closed environments to have reduced syllable diversity. Additionally, our results suggest song complexity may not be ubiquitously a means of communicating male quality, with no significant difference between recordings from monomorphic and dimorphic species. By estimating song complexity in multiple ways, and quantifying these over large taxonomic and spatial scales, we are able to gain a more nuanced understanding of how song complexity is potentially affected by a range of biotic and abiotic factors. Our results also suggest that caution is required when making generalized statements about the relative influence of different factors on song complexity; more densely‐sampled, group‐specific studies are necessary complements to this taxonomically broad analysis.

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Assessing the effect of sound file compression and background noise on measures of acoustic signal structure

Cited by 47 publications

References 31 publications

Vocal divergence between two disjunct populations of Giant Antshrike (Batara cinerea) is related to environmental conditions

Vocal divergence between two disjunct populations of Giant Antshrike (Batara cinerea) is related to environmental conditions

Geographic variation and divergence of songs in the Olive Sparrow species complex

Identifying ecological drivers of interspecific variation in song complexity in songbirds (Passeriformes, Passeri)

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