FIG 5 - uploaded by Zhongchang Song
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Simulated sound signals in different reception points at the forehead in the horizontal plane and 0.8 m away from the source. Points A-Q are the receiving signals located in different positions. The amplitudes of all the waveforms were relative to the highest amplitude of the signals.
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The wave propagation, sound field, and transmission beam pattern of a pygmy sperm whale (Kogia breviceps) were investigated in both the horizontal and vertical planes. Results suggested that the signals obtained at both planes were similarly characterized with a high peak frequency and a relatively narrow bandwidth, close to the ones recorded from...
Citations
... As sounds propagate forward into the forehead, the acoustic structures, including the melon, dense connective tissue layer, upper jaw, nasal passages, and air sacs, modulate sounds into a narrow, forward-oriented beam [8,9]. Beam formation involves a series of stages [10], and the respective functions of various anatomical structures involved in beam modulation have been investigated through modeling [11][12][13][14], suggesting skull structures and acoustic fats are important in achieving directional transmission. ...
Sound reception was investigated in the Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) at its most sensitive frequency. The computed tomography scanning, sound speed, and density results were used to develop a three-dimensional numerical model of the porpoise sound-reception system. The acoustic fields showed that sounds can reach the ear complexes from various pathways, with distinct receptivity peaks on the forward, left, and right sides. Reception peaks were identified on the ipsilateral sides of the respective ears and found on the opposite side of the ear complexes. These opposite maxima corresponded to subsidiary hearing pathways in the whole head, especially the lower head, suggesting the complexity of the sound-reception mechanism in the porpoise. The main and subsidiary sound-reception pathways likely render the whole head a spatial receptor. The low-speed and -density mandibular fats, compared to other acoustic structures, are significant energy enhancers for strengthening forward sound reception. Based on the porpoise reception model, a biomimetic receptor was developed to achieve directional reception, and in parallel to the mandibular fats, the silicon material of low speed and density can significantly improve forward reception. This bioinspired and biomimetic model can bridge the gap between animal sonar and artificial sound control systems, which presents potential to be exploited in manmade sonar.
... In addition, sperm whales (Physeteroidea) are recognized as one of the most diverse groups and include 'macroraptorial' sperm whales such as Acrophyseter and Livyatan [23,24], possible relatives of the present-day Physeter [25], and two clades of pygmy sperm whales (Kogiidae): Scaphokogiinae [26,27] and Kogiinae [28][29][30][31]. Unlike the other toothed cetaceans, both fossil and extant physeteroids are characterized by the presence of a supracranial basin that houses their highly specialized forehead organs, which in turn are responsible for a highly derived sound production system [31,32]. These organs (i.e. the melon and spermaceti) are rich in lipids and fatty oils, being heavily regulated by the surrounding facial muscles [33]. ...
... In extant Kogia, two regions of the melon can be distinguished: an outer region, with a high abundance of triglycerides, and the inner core, with a predominance of wax esters [47]. This gradient of high and low-weight lipids along with the muscular tuning regulates the sound propagation capabilities of the melon by changing the shape of the organ [31,32]. Considering our Peruvian fossil kogiids, bite marks on the rostrum constitute at least 60% of the total number found within each specimen. ...
Shark–cetacean trophic interactions, preserved as bite marks in the fossil record, mostly correspond to isolated or fragmentary findings that bear limited information about major trophic patterns or roles. Here, we provide evidence of focalized foraging by sharks in the form of tooth bite marks over physeteroids fossil bones from the late Miocene of Peru. These findings indicate that sharks were targeting the forehead of coeval physeteroids to actively feed on their lipid-rich nasal complexes. Miocene physeteroids displayed a broad diversity, including giant predatorial forms, small benthic foragers and suction feeders. Like their extant relatives, these animals exhibited enlarged fatty forehead organs responsible for their sound production capabilities, thus evolving taxon-specific cranial architecture. Bite marks are found on the cranial bones where these structures were attached, indicating that sharks actively targeted this region; but also, in areas that would only be accessible following the consumption of the surrounding soft tissues. The shape of the bite marks and their distribution suggests a series of consecutive scavenging events by individuals of different shark species. Similar bite patterns can be recognized on other Miocene physeteroids fossils from across the globe, suggesting that sharks actively exploited physeteroid carcasses as fat sources.
... These conclusions are consistent with previous numerical studies on common dolphin (Delphinus delphis), harbor porpoise (Phocoena phocoena), and bottlenose dolphin (T. truncatus) (Aroyan et al., 1992;Au et al., 2010;Song et al., 2017b;Wei et al., 2017Wei et al., , 2018. Odontocetes are a master in handling the acoustic law. ...
We demonstrated that the feats of the dolphin biosonar system can be achieved through physical implementation. Numerical and experimental results suggested that dolphins have evolved to intelligently manipulate physical laws. Gradient distributions of sound speed and density in the forehead counterpart can enhance the main beam by gathering more sound energy to reinforce the main beam and lowering side lobes. As dolphins prove to accomplish efficient control on their biosonar capabilities in multiple ways, this paper provides an additional aspect to enrich our understanding of how one of the best natural biosonar systems works and build a step to inspire additional advanced sound control systems.
... The odontoncetes evolve to have a sac of oil in their head, called the melon, to do this beamforming. As an example, a model of this effect can be seen in the Kogia in [104]. Sperm whales were thought not to beamform [105], until it was disproven in [106] and further analysed in [107] and [108]. ...
The sperm whale, Physeter macrocephalus, possesses the largest biosonar in nature. Made ofmultiple oil sacs, the sperm whale sonar is tailored to function from the sea surface downto a depth of 2 kilometers, emitting clicks as loud as 236 dB, and is multipurpose, as itproduces clicks for either echolocation or socializing. However, the liquid wax that composesits sonar, made the sperm whales the target of whaling until 1986, when the remainingpopulation was far too small to remain commercially viable, especially with the arrival ofsimilar products from the petrochemical industry. The sperm whale population still facessome human threats, with the ingestion of plastic and collision with boats continuing to takea toll on their numbers. Studying sperm whales thus will have outcomes in multiple fields,in conservation, ethology, as well as in bioacoustics. Understanding the mechanism thatgoverns the sperm whale sonar will help to study these other fields, as it is a key element inthe sperm whale life. Aiming for this goal, this thesis analyzes three databases with distinctcharacteristics, obtaining the trajectory of sperm whale dives. Clicks were also linked withthe sperm whale that emitted them over multiple years of recording of the same population.An efficient End-to-End deep learning classifier was trained to classify biosonar waveforms.A simulation of wave propagation through the sperm whale head was also developed tobetter understand the complex mechanism of this sonar. Finally, a coupling method wasdeveloped to improve the parameters of the simulation using the recorded clicks from theaforementioned databases.
... 通信声信号可结合机器学习、卷积神经网络等人工 智能算法进行识别与分类 [52−54] . 许多研究以通信 [34] ; (c)小抹香鲸头 部声发射系统的水平截面声速重建; (d)小抹香鲸头部声发射系统的垂直截面声速重建 [36] ; (e)中华白海豚头部声发射系统的水 ...
... 平截面声速重建; (f)中华白海豚头部声发射系统的垂直截面声速重建 [38] structions of finless porpoise for sound emission system in vertical section [34] ; (c) sound speed reconstructions of pygmy sperm whale for sound emission system in horizontal section; (d) sound speed reconstructions of pygmy sperm whale for sound emission system in vertical section [36] ; (e) sound speed reconstructions of the Indo-Pacific humpback dolphin for sound emission system in horizontal ...
Odontocetes have evolved for millions of years to own a unique echolocation system. The exceptional performance of odontocetes echolocation system can provide reference to artificial sonar systems, acoustic metamaterials and sound control designs. Research on odontocetes biosonar requires interdisciplinary effort, including acoustics, biology, biomimetics, anatomy, physiology and signal analysis. In this paper, we review odontoctes’ biosonar emission process from aspects of anatomy, biosonar signal and beam formation. To begin, computed tomography scanning and untrasound measurements are combined to reconstruct the sound speed and density distributions. To follow, efforts are thrown to probe into the biosonar signal and its corresponding acoustic behavior. Numerical simulations are used to investigate the odontocetes’ biosonar beam formation. The secret of exceptional performance of odontocetes’ echolocation system lies in their unique anatomy. Odontocete integrates acoustic structures with different acoustic impedances, namely solid bony structures, air space and soft tissues as a whole emission system to efficiently modulate sound propagation and sound beam formation. These acoustic structures are well organized in the forehead, forming a natural acoustic metamaterial to perform a good control of sounds. These results can enlighten artificial sonar designs.
... Odontocetes have a remarkable capability to actively control produced sounds (Au 1993, Au andHastings 2008). This ability stems from their complex sound production and beam formation systems, which involve different sets of anatomical structures including the solid skull, fluid air components and soft tissues (Aroyan et al 1992, Cranford et al 1996, Song et al 2016, 2017b, Wei et al 2015, Zhang et al 2017. The combination of these structures forms a natural acoustic material, which provides a gradient of sound speeds and densities to efficiently influence echolocation beam formation (e.g. ...
... The relationships were then combined with CT scanning data of the whole head to reconstruct its sound speed and density distributions (Zhang et al 2017). Details of the sound speed and density reconstruction could be found in our previous studies , 2017b, Zhang et al 2017. ...
... To meet the computing requirements, the numerical models in figure 2 were meshed into small size elements one-tenth of the wavelength of the sound waves travelling in the media. After sounds were excited at the source, the wave propagations in the models followed the pre-set acoustic equations, which can be found in our previous studies (Song et al 2016, 2017b, Zhang et al 2017. All soft tissues and air components were modeled as fluids, and bony structures were treated as solids in which the shear waves and compressional waves were both considered. ...
Sound transmission and reception are both vital components to odontocete echolocation and daily life. Here, we combine computed tomography (CT) scanning and finite element modeling to investigate the acoustic propagation of finless porpoise (Neophocaena asiaorientalis sunameri) echolocation pulses. The CT scanning and finite element method wave propagation model results support the well-accepted jaw-hearing pathway hypothesis and suggest an additional alternative auditory pathway composed of structures, mandible (lower jaw) and internal mandibular fat, with different acoustic impedances, which may also conduct sounds to the ear complexes. The internal mandibular fat is attached to the ear complex and encased by the mandibles laterally and anteriorly. The simulations show signals in this pathway initially propagate along the solid mandibles and are transmitted to the acoustically coupled soft tissue of the internal mandibular fat which conducts the stimuli posteriorly as it eventually arrives at ear complexes. While supporting traditional theories, this new bone-tissue conduction pathway might be meaningful to understand the hearing and sound reception processes in a wide variety of odontocetes species.
... Simple physical considerations suggest that anatomical features characterized by relatively strong density contrasts with respect to the surrounding medium (water) most significantly contribute to characterizing the HRTF, and thus to sound localization. Since the density of soft tissues found in marine mammal bodies is close to that of water (Norris and Harvey, 1974;Reysenbach de Haan, 1957), it is inferred that features such as the mandible, the cranium, or small air sacs play the most important roles, similar to the external ears of terrestrial mammals (Aroyan et al., 1992;Song et al., 2017;Wei et al., 2016). One important difference in the sound localization performance of terrestrial mammals vs cetaceans is the latter's ability to localize sound sources within the median plane with a very high accuracy (Renaud and Popper, 1975). ...
Mammals use binaural or monaural (spectral) cues to localize acoustic sources. While the sensitivity of terrestrial mammals to changes in source elevation is relatively poor, the accuracy achieved by the odontocete cetaceans' biosonar is high, independently of where the source is. Binaural/spectral cues are unlikely to account for this remarkable skill. In this paper, bone-conducted sound in a dolphin's mandible is studied, investigating its possible contribution to sound localization. Experiments are conducted in a water tank by deploying, on the horizontal and median planes of the skull, ultrasound sources that emit synthetic clicks between 45 and 55 kHz. Elastic waves propagating through the mandible are measured at the pan bones and used to localize source positions via either binaural cues or a correlation-based full-waveform algorithm. Exploiting the full waveforms and, most importantly, reverberated coda, it is possible to enhance the accuracy of source localization in the vertical plane and achieve similar resolution of horizontal- vs vertical-plane sources. The results noted in this paper need to be substantiated by further experimental work, accounting for soft tissues and making sure that the data are correctly mediated to the internal ear. If confirmed, the results would favor the idea that dolphin's echolocation skills rely on the capability to analyze the coda of biosonar echoes.
Odontocete (echolocating whale) skulls exhibit extreme posterior displacement and overlapping of facial bones, here referred to as retrograde cranial telescoping. To examine retrograde cranial telescoping across 40 million years of whale evolution, we collected 3D scans of whale skulls spanning odontocete evolution. We used a sliding semilandmark morphometric approach with Procrustes superimposition and PCA to capture and describe the morphological variation present in the facial region, followed by Ancestral Character State Reconstruction (ACSR) and evolutionary model fitting on significant components to determine how retrograde cranial telescoping evolved. The first PC score explains the majority of variation associated with telescoping and reflects the posterior migration of the external nares and premaxilla alongside expansion of the maxilla and frontal. The earliest diverging fossil odontocetes were found to exhibit a lesser degree of cranial telescoping than later diverging but contemporary whale taxa. Major shifts in PC scores and centroid size are identified at the base of Odontoceti, and early burst and punctuated equilibrium models best fit the evolution of retrograde telescoping. This indicates that the Oligocene was a period of unusually high diversity and evolution in whale skull morphology, with little subsequent evolution in telescoping.
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A dolphin's biosonar may effectively discriminate subtle differences among targets. In order to investigate the possible physical mechanism of target discrimination, in this study, a finite element model excited by a biomimetic click pulse was proposed. The acoustic scattering field and stress distribution of a stainless steel shell were simulated. The biomimetic click experiments were then conducted to verify the theoretical predictions in an anechoic tank. The experimental results showed a good agreement with the model simulations. Furthermore, the elastic time-frequency features of three cylindrical shells with different wall thickness were obtained using a fractional Fourier transform filter to eliminate specular reflection and cross-term interference. To compare discrimination capacity of the time-frequency features with and without the specular reflection, a time-frequency correlator was applied to calculate the correlation coefficient between different shells. The results indicated that the time-frequency features can be represented in high resolution with less cross-term interference, and these features without specular reflection showed a good capacity to discriminate the shells with different wall thickness.
