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1.
J Acoust Soc Am ; 150(3): 1821, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34598611

RESUMO

Small explosive charges, called seal bombs, used by commercial fisheries to deter marine mammals from depredation and accidental bycatch during fishing operations, produce high level sounds that may negatively impact nearby animals. Seal bombs were exploded underwater and recorded at various ranges with a calibrated hydrophone to characterize the pulse waveforms and to provide appropriate propagation loss models for source level (SL) estimates. Waveform refraction became important at about 1500 m slant range with approximately spherical spreading losses observed at shorter ranges. The SL for seal bombs was estimated to be 233 dB re 1 µPa m; however, for impulses such as explosions, better metrics integrate over the pulse duration, accounting for the total energy in the pulse, including source pressure impulse, estimated as 193 Pa m s, and sound exposure source level, estimated as 197 dB re 1 µPa2 m2 s over a 2 ms window. Accounting for the whole 100 ms waveform, including the bubble pulses and sea surface reflections, sound exposure source level was 203 dB re 1 µPa2 m2 s. Furthermore, integrating the energy over an entire event period of multiple explosions (i.e., cumulative sound exposure level) should be considered when evaluating impact.


Assuntos
Bombas (Dispositivos Explosivos) , Ruído , Animais , Explosões , Som , Espectrografia do Som
2.
J Acoust Soc Am ; 150(3): 2189, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34598649

RESUMO

Relatively little is known about spinner dolphins in Malaysian waters and the wider Southeast Asian region. This note represents the first known acoustic recording of the species sighted opportunistically in the northern Straits of Malacca. Over a brief 20 min sighting, 46 whistles were recorded and four tonal types were detected, with 54.4% being upsweep whistles. The whistle duration ranged from 36 to 977 ms and the frequency ranged from 6.6 to 23.8 kHz. Fifty-seven click trains with a mean interclick interval of 41.5 ± 19.3 ms were detected. These findings provide a baseline for future regional acoustic research on this species.


Assuntos
Golfinhos , Stenella , Acústica , Animais , Malásia , Espectrografia do Som , Vocalização Animal
3.
J Acoust Soc Am ; 150(2): 1286, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34470260

RESUMO

In the context of building acoustics and the acoustic diagnosis of an existing room, it introduces and investigates a new approach to estimate the mean absorption coefficients solely from a room impulse response (RIR). This inverse problem is tackled via virtually supervised learning, namely, the RIR-to-absorption mapping is implicitly learned by regression on a simulated dataset using artificial neural networks. Simple models based on well-understood architectures are the focus of this work. The critical choices of geometric, acoustic, and simulation parameters, which are used to train the models, are extensively discussed and studied while keeping in mind the conditions that are representative of the field of building acoustics. Estimation errors from the learned neural models are compared to those obtained with classical formulas that require knowledge of the room's geometry and reverberation times. Extensive comparisons made on a variety of simulated test sets highlight different conditions under which the learned models can overcome the well-known limitations of the diffuse sound field hypothesis underlying these formulas. Results obtained on real RIRs measured in an acoustically configurable room show that at 1 kHz and above, the proposed approach performs comparably to classical models when reverberation times can be reliably estimated and continues to work even when they cannot.


Assuntos
Acústica , Som , Simulação por Computador , Espectrografia do Som , Aprendizado de Máquina Supervisionado
4.
J Acoust Soc Am ; 150(2): 1524, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34470262

RESUMO

In this work, vocal tract characteristic changes under the out-of-breath condition are explored. Speaking under the influence of physical exercise is called out-of-breath speech. The change in breathing pattern results in perceptual changes in the produced sound. For vocal tract, the first four formants show a lowering in their average frequency. The bandwidths BF1 and BF2 widen, whereas the other two get narrowed. The change in bandwidth is small for the last three. For a speaker, the change in frequency and bandwidth may not be uniform across formants. Subband analysis is carried out around formants for comparing the variation of the vocal tract with the source. A vocal tract adaptive empirical wavelet transform is used for extracting formant specific subbands from speech and source. The support vector machine performs the subband-based binary classification between the normal and out-of-breath speech. For all speakers, it shows an F1-score improvement of 4% over speech subbands. Similarly, a performance improvement of 5% can be seen for both male and female speakers. Furthermore, the misclassification amount is less for source compared to speech. These results suggest that physical exercise influences the source more than the vocal tract.


Assuntos
Acústica da Fala , Voz , Feminino , Humanos , Masculino , Espectrografia do Som , Fala
5.
PLoS One ; 16(9): e0257074, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34473797

RESUMO

Changes in the acoustic signalling of animals occupying urban ecosystems is often associated with the masking effects of noise pollution, but the way in which they respond to noise pollution is not straightforward. An increasing number of studies indicate that responses can be case specific, and some species have been found to respond differently to high levels of natural versus anthropogenic noise, as well as different levels of the latter. While the perception of noise between species may vary with its source, amplitude and temporal features, some species may possess broader environmental tolerance to noise pollution, as they use higher frequency vocalizations that are less masked by low-frequency urban noise. In this study, we explored the song variation of two closely related leaf warblers, the Common Chiffchaff Phylloscopus collybita and the Willow Warbler Phylloscopus trochilus, inhabiting urban green spaces and nonurban forests. The main goal of our study was to evaluate the impact of moderate levels of noise pollution on the songs of species which use higher frequency vocalizations and large frequency bandwidth. Previous studies found that the Common Chiffchaff modified their song in response to intense noise pollution, while no such data is available for the Willow Warbler. However, the majority of urban green spaces, which serve as wildlife hot spots in urban environments are usually polluted with moderate noise levels, which may not mask the acoustic signals of species that communicate with higher frequency. We analysed the spectral and temporal song parameters of both warblers and described the ambient noise present in males' territories. Additionally, we looked at the social and seasonal aspects of bird song, since there is more than just noise in urban ecosystems which may affect acoustic communication. We found no evidence for noise-related bird song divergence in either species, however, we showed that social factors, time of day and season influence certain Common Chiffchaff and Willow Warbler song characteristics. Lack of noise-related bird song divergence may be due to the relatively low variation in its amplitude or other noise features present within the song frequency range of the studied species. Similar results have previously been shown for a few songbird species inhabiting urban ecosystems. Although in many cases such results remain in the shadow of the positive ones, they all contribute to a better understanding of animal communication in urban ecosystems.


Assuntos
Ruído , Estações do Ano , Fatores Sociais , Aves Canoras/fisiologia , Vocalização Animal/fisiologia , Animais , Modelos Biológicos , Pressão , Espectrografia do Som , Especificidade da Espécie
6.
J Acoust Soc Am ; 150(1): 225, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34340515

RESUMO

The sound-transmission, beam-formation, and sound-reception processes of a short-finned pilot whale (Globicephala macrorhynchus) were investigated using computed tomography (CT) scanning and numerical simulation. The results showed that sound propagations in the forehead were modulated by the upper jaw, air components, and soft tissues, which attributed to the beam formation in the external acoustic field. These structures owned different acoustic impedance and formed a multiphasic sound transmission system that can modulate sounds into a beam. The reception pathways composed of the solid mandible and acoustic fats in the lower head conducted sounds into the tympano-periotic complex. In the simulations, sounds were emitted in the forehead transmission system and propagated into water to interrogate a steel cylinder. The resulting echoes can be interpreted from multiple perspectives, including amplitude, waveform, and spectrum, to obtain the acoustic cues of the steel cylinder. By taking the short-finned pilot whale as an example, this study provides meaningful information to further deepen our understanding of biosonar system operations, and may expand sound-reception theory in odontocetes.


Assuntos
Baleia Comum , Baleias Piloto , Acústica , Animais , Som , Espectrografia do Som
7.
Sci Rep ; 11(1): 14969, 2021 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-34294820

RESUMO

Potential of ultrasonic vocalizations (USVs) to reflect a degree of discomfort of a caller is mostly investigated in laboratory rats and mice but poorly known in other rodents. We examined 36 (19 male, 17 female) adult yellow steppe lemmings Eolagurus luteus for presence of USVs during 8-min experimental trials including 2-min test stages of increasing discomfort: isolation, touch, handling and body measure. We found that 33 of 36 individuals vocalized at isolation stage, i.e., without any human impact. For 14 (6 male and 8 female) individuals, a repeated measures approach revealed that increasing discomfort from isolation to handling stages resulted in increase of call power quartiles and fundamental frequency, whereas call rate remained unchanged. We discuss that, in adult yellow steppe lemmings, the discomfort-related changes of USV fundamental frequency and power variables follow the same common rule as the audible calls of most mammals, whereas call rate shows a different trend. These data contribute to research focused on searching the universal acoustic cues to discomfort in mammalian USVs.


Assuntos
Arvicolinae/fisiologia , Espectrografia do Som/métodos , Vocalização Animal/fisiologia , Animais , Feminino , Masculino , Isolamento Social , Ultrassom
8.
Sci Rep ; 11(1): 15404, 2021 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-34321592

RESUMO

This work develops a robust classifier for a COVID-19 pre-screening model from crowdsourced cough sound data. The crowdsourced cough recordings contain a variable number of coughs, with some input sound files more informative than the others. Accurate detection of COVID-19 from the sound datasets requires overcoming two main challenges (i) the variable number of coughs in each recording and (ii) the low number of COVID-positive cases compared to healthy coughs in the data. We use two open datasets of crowdsourced cough recordings and segment each cough recording into non-overlapping coughs. The segmentation enriches the original data without oversampling by splitting the original cough sound files into non-overlapping segments. Splitting the sound files enables us to increase the samples of the minority class (COVID-19) without changing the feature distribution of the COVID-19 samples resulted from applying oversampling techniques. Each cough sound segment is transformed into six image representations for further analyses. We conduct extensive experiments with shallow machine learning, Convolutional Neural Network (CNN), and pre-trained CNN models. The results of our models were compared to other recently published papers that apply machine learning to cough sound data for COVID-19 detection. Our method demonstrated a high performance using an ensemble model on the testing dataset with area under receiver operating characteristics curve = 0.77, precision = 0.80, recall = 0.71, F1 measure = 0.75, and Kappa = 0.53. The results show an improvement in the prediction accuracy of our COVID-19 pre-screening model compared to the other models.


Assuntos
COVID-19/diagnóstico , Tosse/classificação , COVID-19/epidemiologia , Tosse/virologia , Aprendizado Profundo , Humanos , Aprendizado de Máquina , Programas de Rastreamento/métodos , Redes Neurais de Computação , Curva ROC , SARS-CoV-2/isolamento & purificação , Sensibilidade e Especificidade , Som , Espectrografia do Som/métodos , Tomografia Computadorizada por Raios X/métodos
9.
J Acoust Soc Am ; 149(5): 3241, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-34241090

RESUMO

The vocal repertoire of the pantropical spotted dolphin (Stenella attenuata) is poorly documented, with no published information about acoustic signals from South Atlantic Ocean populations. We conducted passive acoustic monitoring and recording of S. attenuata population in the Santos Basin, Brazil, using a towed hydrophone array during line-transects surveys. Our monitoring yielded whistle samples derived from eight groups of S. attenuata, from which we selected 155 whistles for further analysis. Approximately 48% of the whistles presented ultrasonic frequency values, with maximum frequencies up to 31.1 kHz. Across the sample, the number of steps ranged from 0 to 20 and inflection points ranged from 0 to 8. On average, end frequencies were higher than start frequencies, and whistles generally presented wide frequency ranges, with an average of 11.3 kHz. The most predominant whistle contour category was "ascending-descending." Our study provides new information regarding the acoustic repertoire of this poorly documented species and will aid efforts for using acoustics to identify and monitor cetaceans in this region.


Assuntos
Golfinho Nariz-de-Garrafa , Stenella , Animais , Oceano Atlântico , Brasil , Espectrografia do Som , Vocalização Animal
10.
Sci Rep ; 11(1): 11847, 2021 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-34088923

RESUMO

Acoustical geographic variation is common in widely distributed species and it is already described for several taxa, at various scales. In cetaceans, intraspecific variation in acoustic repertoires has been linked to ecological factors, geographical barriers, and social processes. For the common bottlenose dolphin (Tursiops truncatus), studies on acoustic variability are scarce, focus on a single signal type-whistles and on the influence of environmental variables. Here, we analyze the acoustic emissions of nine bottlenose dolphin populations across the Atlantic Ocean and the Mediterranean Sea, and identify common signal types and acoustic variants to assess repertoires' (dis)similarity. Overall, these dolphins present a rich acoustic repertoire, with 24 distinct signal sub-types including: whistles, burst-pulsed sounds, brays and bangs. Acoustic divergence was observed only in social signals, suggesting the relevance of cultural transmission in geographic variation. The repertoire dissimilarity values were remarkably low (from 0.08 to 0.4) and do not reflect the geographic distances among populations. Our findings suggest that acoustic ecology may play an important role in the occurrence of intraspecific variability, as proposed by the 'environmental adaptation hypothesis'. Further work may clarify the boundaries between neighboring populations, and shed light into vocal learning and cultural transmission in bottlenose dolphin societies.


Assuntos
Acústica , Golfinho Nariz-de-Garrafa/fisiologia , Som , Vocalização Animal/fisiologia , Animais , Oceano Atlântico , Comportamento Animal , Biodiversidade , Ecologia , Geografia , Mar Mediterrâneo , Espectrografia do Som
11.
Artif Intell Med ; 117: 102085, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34127246

RESUMO

BACKGROUND AND PURPOSE: Snoring is one of the sleep disorders, and snoring sounds have been used to diagnose many sleep-related diseases. However, the snoring sound classification is done manually which is time-consuming and prone to human errors. An automated snoring sound classification model is proposed to overcome these problems. MATERIAL AND METHOD: This work proposes an automated snoring sound classification method using three new methods. These methods are maximum absolute pooling (MAP), the nonlinear present pattern, and two-layered neighborhood component analysis, and iterative neighborhood component analysis (NCAINCA) selector. Using these methods, a new snoring sound classification (SSC) model is presented. The MAP decomposition model is applied to snoring sounds to extract both low and high-level features. The presented model aims to attain high performance for SSC problem. The developed present pattern (Present-Pat) uses substitution box (SBox) and statistical feature generator. By deploying these feature generators, both textural and statistical features are generated. NCAINCA chooses the most informative/valuable features, and these selected features are fed to k-nearest neighbor (kNN) classifier with leave-one-out cross-validation (LOOCV). The Present-Pat based SSC system is developed using Munich-Passau Snore Sound Corpus (MPSSC) dataset comprising of four categories. RESULTS: Our model reached an accuracy and unweighted average recall (UAR) of 97.10 % and 97.60 %, respectively, using LOOCV. Moreover, a nocturnal sound dataset is used to show the universal success of the presented model. Our model attained an accuracy of 98.14 % using the used nocturnal sound dataset. CONCLUSIONS: Our developed classification model is ready to be tested with more data and can be used by sleep specialists to diagnose the sleep disorders based on snoring sounds.


Assuntos
Ronco , Som , Análise por Conglomerados , Humanos , Polissonografia , Ronco/diagnóstico , Espectrografia do Som
12.
Atten Percept Psychophys ; 83(6): 2694-2708, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33987821

RESUMO

Speech perception, like all perception, takes place in context. Recognition of a given speech sound is influenced by the acoustic properties of surrounding sounds. When the spectral composition of earlier (context) sounds (e.g., a sentence with more energy at lower third formant [F3] frequencies) differs from that of a later (target) sound (e.g., consonant with intermediate F3 onset frequency), the auditory system magnifies this difference, biasing target categorization (e.g., towards higher-F3-onset /d/). Historically, these studies used filters to force context stimuli to possess certain spectral compositions. Recently, these effects were produced using unfiltered context sounds that already possessed the desired spectral compositions (Stilp & Assgari, 2019, Attention, Perception, & Psychophysics, 81, 2037-2052). Here, this natural signal statistics approach is extended to consonant categorization (/g/-/d/). Context sentences were either unfiltered (already possessing the desired spectral composition) or filtered (to imbue specific spectral characteristics). Long-term spectral characteristics of unfiltered contexts were poor predictors of shifts in consonant categorization, but short-term characteristics (last 475 ms) were excellent predictors. This diverges from vowel data, where long-term and shorter-term intervals (last 1,000 ms) were equally strong predictors. Thus, time scale plays a critical role in how listeners attune to signal statistics in the acoustic environment.


Assuntos
Fonética , Percepção da Fala , Estimulação Acústica , Humanos , Idioma , Som , Espectrografia do Som , Acústica da Fala
13.
J Acoust Soc Am ; 149(4): 2908, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33940877

RESUMO

Modern active sonar systems can (almost) continuously transmit and receive sound, which can lead to more masking of important sounds for marine mammals than conventional pulsed sonar systems transmitting at a much lower duty cycle. This study investigated the potential of 1-2 kHz active sonar to mask echolocation-based foraging of sperm whales by modeling their echolocation detection process. Continuous masking for an echolocating sperm whale facing a sonar was predicted for sonar sound pressure levels of 160 dB re 1 µPa2, with intermittent masking at levels of 120 dB re 1 µPa2, but model predictions strongly depended on the animal orientation, harmonic content of the sonar, click source level, and target strength of the prey. The masking model predicted lower masking potential of buzz clicks compared to regular clicks, even though the energy source level is much lower. For buzz clicks, the lower source level is compensated for by the reduced two-way propagation loss to nearby prey during buzzes. These results help to predict what types of behavioral changes could indicate masking in the wild. Several key knowledge gaps related to masking potential of sonar in echolocating odontocetes were identified that require further investigation to assess the significance of masking.


Assuntos
Ecolocação , Cachalote , Animais , Som , Espectrografia do Som , Baleias
14.
Mar Pollut Bull ; 168: 112437, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33957495

RESUMO

The Arctic has been a refuge from anthropogenic underwater noise; however, climate change has caused summer sea ice to diminish, allowing for unprecedented access and the potential for increased underwater noise. Baseline underwater sound levels must be quantified to monitor future changes and manage underwater noise in the Arctic. We analyzed 39 passive acoustic datasets collected throughout the Canadian Arctic from 2014 to 2019 using statistical models to examine spatial and temporal trends in daily mean sound pressure levels (SPL) and quantify environmental and anthropogenic drivers of SPL. SPL (50-1000 Hz) ranged from 70 to 127 dB re 1 µPa (median = 91 dB). SPL increased as wind speed increased, but decreased as both ice concentration and air temperature increased, and SPL increased as the number of ships per day increased. This study provides a baseline for underwater sound levels in the Canadian Arctic and fills many geographic gaps on published underwater sound levels.


Assuntos
Acústica , Som , Regiões Árticas , Canadá , Ruído , Espectrografia do Som
15.
Nat Commun ; 12(1): 2562, 2021 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-33963187

RESUMO

Songbirds acquire songs by imitation, as humans do speech. Although imitation should drive convergence within a group and divergence through drift between groups, zebra finch songs sustain high diversity within a colony, but mild variation across colonies. We investigated this phenomenon by analyzing vocal learning statistics in 160 tutor-pupil pairs from a large breeding colony. Song imitation is persistently accurate in some families, but poor in others. This is not attributed to genetic differences, as fostered pupils copied their tutors' songs as accurately or poorly as biological pupils. Rather, pupils of tutors with low song diversity make more improvisations compared to pupils of tutors with high song diversity. We suggest that a frequency dependent balanced imitation prevents extinction of rare song elements and overabundance of common ones, promoting repertoire diversity within groups, while constraining drift across groups, which together prevents the collapse of vocal culture into either complete uniformity or chaos.


Assuntos
Comportamento Imitativo/classificação , Aprendizagem , Espectrografia do Som/classificação , Vocalização Animal/classificação , Animais , Feminino , Tentilhões , Masculino
16.
Am J Primatol ; 83(5): e23249, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33792937

RESUMO

Human vocal ontogeny is considered to be a process whereby a large repertoire of discrete sounds seemingly emerges from a smaller number of acoustically graded vocalizations. While adult chimpanzee vocal behavior is highly graded, its developmental trajectory is poorly understood. In the present study, we therefore examined the size and structure of the chimpanzee vocal repertoire at different stages of ontogeny. Audio recordings were collected on infant (N = 13) and juvenile (N = 13) semi-wild chimpanzees at Chimfunshi Wildlife Orphanage, Zambia, using focal and ad libitum sampling. All observed call types were acoustically measured. These were predominantly grunts, whimpers, laughs, screams, hoos, and barks and squeaks. A range of spectral and temporal acoustic parameters were extracted, and fuzzy c-means clustering was used to quantify the size and structure of the repertoire. The infant and juvenile vocal repertoires were both best described with the same number of clusters. However, compared to infants, juvenile call clusters were less distinct from one another and could be extracted only when a low level of overlap between call clusters was permitted. Moreover, the acoustic overlap between call clusters was significantly higher for juveniles. Overall, this pattern shows greater acoustic overlap in juvenile vocalizations compared to infants, suggesting a trend toward increased acoustic gradation in chimpanzee vocal ontogeny. This may imply in contrast to humans, chimpanzees become increasingly proficient in using graded signals effectively rather than developing a larger repertoire of more discrete sounds in ontogeny.


Assuntos
Pan troglodytes , Vocalização Animal , Acústica , Animais , Espectrografia do Som
17.
Sci Rep ; 11(1): 8762, 2021 04 22.
Artigo em Inglês | MEDLINE | ID: mdl-33888792

RESUMO

Blue whales were brought to the edge of extinction by commercial whaling in the twentieth century and their recovery rate in the Southern Hemisphere has been slow; they remain endangered. Blue whales, although the largest animals on Earth, are difficult to study in the Southern Hemisphere, thus their population structure, distribution and migration remain poorly known. Fortunately, blue whales produce powerful and stereotyped songs, which prove an effective clue for monitoring their different 'acoustic populations.' The DGD-Chagos song has been previously reported in the central Indian Ocean. A comparison of this song with the pygmy blue and Omura's whale songs shows that the Chagos song are likely produced by a distinct previously unknown pygmy blue whale population. These songs are a large part of the underwater soundscape in the tropical Indian Ocean and have been so for nearly two decades. Seasonal differences in song detections among our six recording sites suggest that the Chagos whales migrate from the eastern to western central Indian Ocean, around the Chagos Archipelago, then further east, up to the north of Western Australia, and possibly further north, as far as Sri Lanka. The Indian Ocean holds a greater diversity of blue whale populations than thought previously.


Assuntos
Balaenoptera/fisiologia , Vocalização Animal , Migração Animal , Animais , Oceano Índico , Estações do Ano , Espectrografia do Som , Especificidade da Espécie
18.
Sci Rep ; 11(1): 6660, 2021 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-33758251

RESUMO

Detailed neural encoding of voice pitch and formant structure plays a crucial role in speech perception, and is of key importance for an appropriate acquisition of the phonetic repertoire in infants since birth. However, the extent to what newborns are capable of extracting pitch and formant structure information from the temporal envelope and the temporal fine structure of speech sounds, respectively, remains unclear. Here, we recorded the frequency-following response (FFR) elicited by a novel two-vowel, rising-pitch-ending stimulus to simultaneously characterize voice pitch and formant structure encoding accuracy in a sample of neonates and adults. Data revealed that newborns tracked changes in voice pitch reliably and no differently than adults, but exhibited weaker signatures of formant structure encoding, particularly at higher formant frequency ranges. Thus, our results indicate a well-developed encoding of voice pitch at birth, while formant structure representation is maturing in a frequency-dependent manner. Furthermore, we demonstrate the feasibility to assess voice pitch and formant structure encoding within clinical evaluation times in a hospital setting, and suggest the possibility to use this novel stimulus as a tool for longitudinal developmental studies of the auditory system.


Assuntos
Estimulação Acústica , Encéfalo/fisiologia , Percepção da Altura Sonora , Voz , Adulto , Fatores Etários , Biomarcadores , Cognição , Humanos , Recém-Nascido , Pediatria , Espectrografia do Som , Percepção da Fala
19.
J Exp Biol ; 224(Pt 6)2021 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-33771935

RESUMO

Dwarf sperm whales (Kogia sima) are small toothed whales that produce narrow-band high-frequency (NBHF) echolocation clicks. Such NBHF clicks, subject to high levels of acoustic absorption, are usually produced by small, shallow-diving odontocetes, such as porpoises, in keeping with their short-range echolocation and fast click rates. Here, we sought to address the problem of how the little-studied and deep-diving Kogia can hunt with NBHF clicks in the deep sea. Specifically, we tested the hypotheses that Kogia produce NBHF clicks with longer inter-click intervals (ICIs), higher directionality and higher source levels (SLs) compared with other NBHF species. We did this by deploying an autonomous deep-water vertical hydrophone array in the Bahamas, where no other NBHF species are present, and by taking opportunistic recordings of a close-range Kogia sima in a South African harbour. Parameters from on-axis clicks (n=46) in the deep revealed very narrow-band clicks (root mean squared bandwidth, BWRMS, of 3±1 kHz), with SLs of up to 197 dB re. 1 µPa peak-to-peak (µPapp) at 1 m, and a half-power beamwidth of 8.8 deg. Their ICIs (mode of 245 ms) were much longer than those of porpoises (<100 ms), suggesting an inspection range that is longer than detection ranges of single prey, perhaps to facilitate auditory streaming of a complex echo scene. On-axis clicks in the shallow harbour (n=870) had ICIs and SLs in keeping with source parameters of other NBHF cetaceans. Thus, in the deep, dwarf sperm whales use a directional, but short-range echolocation system with moderate SLs, suggesting a reliable mesopelagic prey habitat.


Assuntos
Ecolocação , Acústica , Animais , Ecossistema , Espectrografia do Som , Vocalização Animal , Baleias
20.
J Acoust Soc Am ; 149(3): 1923, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33765819

RESUMO

Short-finned pilot whales (Globicephala macrorhynchus) are large, deep-diving predators with diverse foraging strategies, but little is known about their echolocation. To quantify the source properties of short-finned pilot whale clicks, we made 15 deployments off the coast of Tenerife of a deep-water hydrophone array consisting of seven autonomous time-synced hydrophone recorders (SoundTraps), enabling acoustic localization and quantification of click source parameters. Of 8185 recorded pilot whale clicks, 47 were classified as being recorded on-axis, with a mean peak-to-peak source level (SL) of 181 ± 7 dB re 1 µPa, a centroid frequency of 40 ± 4 kHz, and a duration of 57 ± 23 µs. A fit to a piston model yielded an estimated half-power (-3 dB) beam width of 13.7° [95% confidence interval (CI) 13.2°-14.5°] and a mean directivity index (DI) of 22.6 dB (95% CI 22.5-22.9 dB). These measured SLs and DIs are surprisingly low for a deep-diving toothed whale, suggesting we sampled the short-finned pilot whales in a context with little need for operating a long-range biosonar. The substantial spectral overlap with beaked whale clicks emitted in similar deep-water habitats implies that pilot whale clicks may constitute a common source of false detections in beaked whale passive acoustic monitoring efforts.


Assuntos
Ecolocação , Baleia Comum , Baleias Piloto , Acústica , Animais , Espectrografia do Som , Vocalização Animal , Baleias
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