@article {53527,
	title = {Bats increase vocal amplitude and decrease vocal complexity to mitigate noise interference during social communication},
	journal = {Animal Cognition},
	year = {2019},
	month = {Oct-01-2019},
	abstract = {<p>Natural background noises are common in the acoustic environments in which most organisms have evolved. Therefore, the vocalization and sound perception systems of vocal animals are inherently equipped to overcome natural background noise. Human-generated noises, however, pose new challenges that can hamper audiovocal communication. The mechanisms animals use to cope with anthropogenic noise disturbances have been extensively explored in a variety of taxa. Bats emit echolocation pulses primarily to orient, locate and navigate, while social calls are used to communicate with conspecifics. Previous studies have shown that bats alter echolocation pulse parameters in response to background noise interference. In contrast to high-frequency echolocation pulses, relatively low-frequency components within bat social calls overlap broadly with ambient noise frequencies. However, how bats structure their social calls in the presence of anthropogenic noise is not known. Here, we hypothesized that bats leverage vocal plasticity to facilitate vocal exchanges within a noisy environment. To test this hypothesis, we subjected the Asian particolored bat, Vespertilio sinensis, to prerecorded traffic noise. We observed a significant decrease in vocal complexity (i.e., an increased frequency of monosyllabic calls) in response to traffic noise. However, an increase in the duration and frequency of social calls, as have been observed in other species, was not evident. This suggests that signal simplification may increase communication efficacy in noisy environments. Moreover, V. sinensis also increased call amplitude in response to increased traffic noise, consistent with the predictions of the Lombard effect.</p>
},
	keywords = {acoustic communication, bats, Noise, Social calls, vocal plasticity},
	issn = {1435-9448},
	doi = {10.1007/s10071-018-01235-0},
	url = {http://link.springer.com/10.1007/s10071-018-01235-0},
	author = {Jiang, Tinglei and Guo, Xiong and Lin, Aiqing and Wu, Hui and Sun, Congnan and Feng, Jiang and Kanwal, Jagmeet S.}
}
@article {53114,
	title = {The vocal repertoire of the domesticated zebra finch: a data-driven approach to decipher the information-bearing acoustic features of communication signals},
	journal = {Animal Cognition},
	volume = {19},
	year = {2016},
	month = {Jan-03-2016},
	pages = {285 - 315},
	abstract = {<p>Although a universal code for the acoustic features of animal vocal communication calls may not exist, the thorough analysis of the distinctive acoustical features of vocalization categories is important not only to decipher the acoustical code for a specific species but also to understand the evolution of communication signals and the mechanisms used to produce and understand them. Here, we recorded more than 8000 examples of almost all the vocalizations of the domesticated zebra finch, Taeniopygia guttata: vocalizations produced to establish contact, to form and maintain pair bonds, to sound an alarm, to communicate distress or to advertise hunger or aggressive intents. We characterized each vocalization type using complete representations that avoided any a priori assumptions on the acoustic code, as well as classical bioacoustics measures that could provide more intuitive interpretations. We then used these acoustical features to rigorously determine the potential information-bearing acoustical features for each vocalization type using both a novel regularized classifier and an unsupervised clustering algorithm. Vocalization categories are discriminated by the shape of their frequency spectrum and by their pitch saliency (noisy to tonal vocalizations) but not particularly by their fundamental frequency. Notably, the spectral shape of zebra finch vocalizations contains peaks or formants that vary systematically across categories and that would be generated by active control of both the vocal organ (source) and the upper vocal tract (filter).</p>
},
	keywords = {Acoustic signature, classification, Meaning, Regularization, Songbird, vocalization},
	issn = {1435-9448},
	doi = {10.1007/s10071-015-0933-6},
	url = {http://link.springer.com/10.1007/s10071-015-0933-6},
	author = {Elie, Julie E. and Theunissen, Fr{\'e}d{\'e}ric E.}
}
