Ear Deformations Give Bats a Physical Mechanism for Fast Adaptation of Ultrasonic Beam Patterns

Gao, Li; Balakrishnan, Sreenath; He, Weikai; Yan, Zhen; Müller, Rolf

doi:10.1103/physrevlett.107.214301

Cited by 66 publications

(90 citation statements)

References 24 publications

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“…By using their unique sound focusing structures, odontocetes can optimize the energy impinging on a target, which would result in increased target detection, discrimination and overall foraging success. Anatomical adaptation is common in many other animals and across sensory modalities (Estes, 1972;Forrester et al, 1996;Gao et al, 2011). Therefore, our proposed focusing mechanism for odontocetes is not unusual, but rather is consistent with adaptive sensory behavior clearly demonstrated in many other animal species.…”

Section: Discussionmentioning

confidence: 48%

Support for the beam focusing hypothesis in the false killer whale

Kloepper

Buck

Smith

et al. 2015

Journal of Experimental Biology

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The odontocete sound production system is complex and composed of tissues, air sacs and a fatty melon. Previous studies suggested that the emitted sonar beam might be actively focused, narrowing depending on target distance. In this study, we further tested this beam focusing hypothesis in a false killer whale. Using three linear arrays of hydrophones, we recorded the same emitted click at 2, 4 and 7 m distance and calculated the beamwidth, intensity, center frequency and bandwidth as recorded on each array at every distance. If the whale did not focus her beam, acoustics predicts the intensity would decay with range as a function of spherical spreading and the angular beamwidth would remain constant. On the contrary, our results show that as the distance from the whale to the array increases, the beamwidth is narrower and the received click intensity is higher than that predicted by a spherical spreading function. Each of these measurements is consistent with the animal focusing her beam on a target at a given range. These results support the hypothesis that the false killer whale is 'focusing' its sonar beam, producing a narrower and more intense signal than that predicted by spherical spreading.

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Section: Discussionmentioning

confidence: 48%

Support for the beam focusing hypothesis in the false killer whale

Kloepper

Buck

Smith

et al. 2015

Journal of Experimental Biology

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“…In bats, for example, the movement of the ears is fast and unpredictable, and is of special importance because of the bats' superior localization ability. Researchers have previously used high-speed video to capture this movement (Gao et al, 2011), but have not benefited from automated detection of events. Similarly, the method can be used to analyze interactions between cleaner fish and their clients (Bshary and Grutter, 2002;Bshary and Würth, 2001), which hitherto required laborious processing of videos and may be strongly biased by the subjectivity of the observer.…”

Section: Discussionmentioning

confidence: 99%

Automated detection of feeding strikes by larval fish using continuous high-speed digital video: a novel method to extract quantitative data from fast, sparse kinematic events

Shamur

Zilka

Hassner

et al. 2016

Journal of Experimental Biology

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Using videography to extract quantitative data on animal movement and kinematics constitutes a major tool in biomechanics and behavioral ecology. Advanced recording technologies now enable acquisition of long video sequences encompassing sparse and unpredictable events. Although such events may be ecologically important, analysis of sparse data can be extremely time-consuming and potentially biased; data quality is often strongly dependent on the training level of the observer and subject to contamination by observer-dependent biases. These constraints often limit our ability to study animal performance and fitness. Using long videos of foraging fish larvae, we provide a framework for the automated detection of prey acquisition strikes, a behavior that is infrequent yet critical for larval survival. We compared the performance of four video descriptors and their combinations against manually identified feeding events. For our data, the best single descriptor provided a classification accuracy of 77-95% and detection accuracy of 88-98%, depending on fish species and size. Using a combination of descriptors improved the accuracy of classification by ∼2%, but did not improve detection accuracy. Our results indicate that the effort required by an expert to manually label videos can be greatly reduced to examining only the potential feeding detections in order to filter false detections. Thus, using automated descriptors reduces the amount of manual work needed to identify events of interest from weeks to hours, enabling the assembly of an unbiased large dataset of ecologically relevant behaviors.

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“…These shape changes are driven by specialized musculatures (Schneider and Möhres 1960;Schneider 1961;Göbbel 2002) and are known to occur during pulse emission (for the noseleaf (Feng et al2012;He et al 2015)) or echo reception (for the pinnae (Yin et al 2015)). Noseleaf and pinna motions are fast and occur on a similar time scale as the durations of the biosonar pulses and echoes (Gao et al 2011;Feng et al 2012;He et al 2015). Hence, these motions could change the acoustic characteristics of the biosonar emission and reception during a single pulse or a single echo.…”

Section: Dynamic Information Encoding: Noseleaf and Pinna Motionsmentioning

confidence: 99%

“…Hence, these motions could change the acoustic characteristics of the biosonar emission and reception during a single pulse or a single echo. Indeed, such changes have been predicted by numerical analysis (Gao et al 2011;He et al 2015) and demonstrated with biomimetic physical prototypes Fu et al 2016). Time variant acoustic characteristics would allow the bats to sense their environments through "multiple views" and hence could enhance the quantity -and perhaps also the quality -of the sensory information available to the animals.…”

Section: Dynamic Information Encoding: Noseleaf and Pinna Motionsmentioning

confidence: 99%

Quantitative approaches to sensory information encoding by bat noseleaves and pinnae

Müller

2018

Can. J. Zool.

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The biosonar systems of horseshoe bats (Rhinolophidae) and Old World round leaf-nosed bats (Hipposideridae) incorporate a pervasive dynamic at the interfaces for ultrasound emission (noseleaves) and reception (pinnae). Changes in the shapes of these structures alter the acoustic characteristics of the biosonar system and could hence influence the encoding of sensory information. The focus of the present work is on approaches that can be used to investigate the hypothesis that the interface dynamic effects sensory information encoding. Mutual information can be used as a metric to quantify the extent to which the different ultrasonic emission and reception characteristics (beampatterns) provide independent views of the environment. Two different quantitative approaches have been taken to evaluate the relationship between dynamically encoded additional sensory information and sensing performance in finding the direction of a biosonar target. The first approach is to determine an upper bound on the number of different directions that can be distinguished by virtue of distinct spectral signatures. The second approach is based on a lower bound (Cramér–Rao) on the variance of direction estimates. All these different metrics demonstrate that the peripheral dynamics seen in bats result in the encoding of additional sensory information that is suitable for enhancing biosonar performance.

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Ear Deformations Give Bats a Physical Mechanism for Fast Adaptation of Ultrasonic Beam Patterns

Cited by 66 publications

References 24 publications

Support for the beam focusing hypothesis in the false killer whale

Support for the beam focusing hypothesis in the false killer whale

Automated detection of feeding strikes by larval fish using continuous high-speed digital video: a novel method to extract quantitative data from fast, sparse kinematic events

Quantitative approaches to sensory information encoding by bat noseleaves and pinnae

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