Thesis (Ph.D.)-- University of Adelaide, Dept of Zoology, 1982. / Typescript (photocopy).

Bats are noted for having extremely powerful biosonar systems that enable them to move through and hunt through the thick foliage. They have a single emitter (mouth or nose) and two receivers in their biosonar system (ears). Some bat species, such as those belonging to the group's rhinophid and hipposiderid, feature intricate pinna motion patterns. These pinnae are divided into two groups: stiff movements and non-rigid motions. To understand how pinna sense worked has been studied in this thesis. The rigid pinna movements displayed a significantly different rotation, with revolutions axes spanning 180° in horizontal and curvature, according to axis-angle representations. The classification of landmarks on the pinna surface has explained two types of non-stiffed pinna movements. Additionally, a bio-inspired pinna has been used to explore the acoustic impact of the stiff pinna movements. All the given results showed precise accuracy in the motion of variance bats pinnae. The research initiative was initiated with a comprehensive exploration of various design concepts, primarily focused on elucidating the intricate interplay between actuator geometry and the resultant deformation of the pinna. Employing a structured design code facilitated the generation of an array of configurations, each subject to stringent conditions and parameter settings necessitating subsequent validation. After this design exploration, a tri-tiered hierarchy of forces, encompassing nominal, intermediate, and elevated magnitudes, was applied to instigate a systematic optimization process aimed at determining the most favorable deformation pattern. Computational simulations leveraging Finite Element Analysis (FEA) were conducted, accompanied by a rigorous material characterization procedure, to effectively quantify the extent of deformation across the array of configurations. A consequential phase of the investigation involved the implementation of Principal Component Analysis (PCA) to differentiate the inherent variability within the different deformation arrangements, shedding light on their relative structural and morphological distinctions. The culmination of the study encompassed the utilization of the Genetic Algorithm (GA), a sophisticated optimization technique, to facilitate the fine-tuning of deformation patterns in pursuit of the overarching goal: the deliberate induction of substantial and diverse variations in pinna morphology. In summary, the research trajectory progressed sequentially through design conceptualization, force-induced optimization, computational simulations incorporating FEA and material characterization, Variability analysis via PCA, and culminated in the deployment of the GA to achieve the prime objective of inducing pronounced variability in pinna configuration. The work was done as following, starting with design concepts, the main benefit of this is to understand how the geometry of actuator affects the pinna deformation. Using the design code to present several configurations that must have conditions and parameters to be validated. After that applying 3 different forces (zero, medium, and high) to get the optimization for pattern. Applying the FEA simulations with help of material characterization to display the displacement of the arrangements. Finally doing the Variability analysis by using the principal component analysis. Then concluding the work by using the Genetic algorithm for optimizations to reach the main goal which is large variability in the pinna shape. / Doctor of Philosophy / This research delves into the fascinating world of bats and their extraordinary biosonar systems, specifically focusing on the intricate mechanics of their pinnae—the external ear structures. Bats, known for their remarkable ability to navigate dense foliage using biosonar, have been a subject of keen scientific interest. The study explores the design and functionality of bat pinnae, with a special emphasis on understanding how different movements contribute to their biosonar capabilities. The investigation began with a comprehensive exploration of design concepts, aiming to unravel the complex relationship between actuator geometry and pinna deformation. A structured design code was employed to generate a range of configurations, each subjected to stringent conditions and parameters, requiring subsequent validation. Following this design exploration, a three-tiered hierarchy of forces—ranging from nominal to elevated magnitudes—was applied to initiate a systematic optimization process. Computational simulations, utilizing Finite Element Analysis (FEA) and rigorous material characterization, were conducted to quantify the extent of pinna deformation across various configurations. The study further implemented Principal Component Analysis (PCA) to discern inherent variability in different deformation patterns, shedding light on their structural and morphological distinctions. The research culminated in the deployment of the Genetic Algorithm (GA), a sophisticated optimization technique, to deliberately induce substantial and diverse variations in pinna morphology. In summary, the research trajectory progressed from design conceptualization to force-induced optimization, incorporating computational simulations and material characterization. Variability analysis through PCA provided insights into structural distinctions, and the use of the Genetic Algorithm aimed at achieving the overarching goal of inducing pronounced variability in pinna configuration. This work not only enhances our understanding of bat biosonar systems but also offers potential applications in bio-inspired design and acoustic engineering.

Typescript (photocopy) / 310 leaves : ill., map ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Zoology, 1982

Typescript (photocopy) / 310 leaves : ill., map ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Zoology, 1982

Mon étude, effectuée en République dominicaine, indique que Pinna carnea est un mollusque que l'on trouve dans les prés sous-marins et non pas dans les replats sableux adjacents. Les densités de population étaient basses (1-7/100 m2) et les structures de taille étaient biaisées envers les gros individus. Des expériences indiquent, que les larves n'ont pas de préférence de substrat lors de la fixation, qu'il y a moins de prédation chez les gros individus, et qu'il y a une mortalité réduite dans les prés sous-marins. P. carnea semble être limité aux prés sous-marins car cet habitat fournit une protection contre les prédateurs et les perturbations physiques. La croissance juvénile rapide peut être une stratégie évolutive pour réduire sa vulnérabilité aux prédateurs. La prédominance de gros individus peut représenter une accumulation d'événements de recrutement causée par le ralentissement de croissance lorsqu'ils ont atteint >150 mm de longueur.

We examined aspects of hearing in the red bat (Lasiurus borealis) related to its use of biosonar. Evoked potential audiograms, obtained from volume-conducted auditory brainstem responses, were obtained in two bats, and the sound pressure transformation of the pinna was measured in three specimens. Field-recorded echolocation signals were analysed for comparison. The fundamental sonar search calls sweep from 45 to 30 kHz (peak energy at 35 kHz), approach-phase calls sweep from 65 to 35 kHz (peak 40 kHz) and terminal calls sweep from 70 to 30 kHz (peak 45 kHz). The most sensitive region of the audiogram extended from 10 kHz to 45-55 kHz, with maximum sensitivity as low as 20 dB SPL occurring between 25 and 30 kHz. A relative threshold minimum occurred between 40 and 50 kHz. With increasing frequency, the acoustic axis of the pinna moves upwards and medially. The sound pressure transformation was noteworthy near 40-45 kHz; the acoustic axis was closest to the midline, the -3 dB acceptance angles showed local minima, and the pinna gain and interaural intensity difference were maximal. These results are related to the known echolocation and foraging behavior of this species and match the spectral components of approach- and final-phase calls. We conclude that coevolution with hearing prey has put a higher selective pressure on optimizing localization and tracking of prey than on improving detection performance.

Bats are known for their highly capable biosonar systems which make them be able to navigate and forage in dense vegetation. Their biosonar system consists of one emitter (nose or mouth) and two receivers (ears). Some bat species, e.g. in the rhinolophid and hipposiderid families, have complicated pinna motion patterns. It has been shown that these pinna motion patterns fall into two distinct categories: rigid motions and non-rigid motions. In the current work, the pinna of Pratt's leaf-nosed bat (Hipposideros pratti) was used as a biological model system to understand how a sensor could benefit from variability. Hence, the variability in the rigid pinna motions and in the non-rigid pinna motions has been investigated by tracking a dense set of landmarks on the pinna surface with stereo vision. Axis-angle representations have shown that the rigid pinna motions exhibited a large continuous variation with rotation axes covering 180 degrees in azimuth and elevation. Distributions of clusters of the landmarks on the pinna surface have shown that the non-rigid pinna motions fall into at least two subgroups. Besides, the acoustic impact of the rigid pinna motions have been investigated using a biomimetic pinna. Normalized mutual information between the acoustic inputs with different rotation axes has shown that different rotation axes can provide at least 50% new sensory information. These results demonstrate that the variability in the pinna motions is an interesting concept for sensor, and how the bats approach that needs to be further investigated. / Master of Science / Sensors have been developed for a long time, and they can be used to detect the environments and then deliver the required sensing information. There are many different types of sensors, such as vision-based sensors (infrared camera and laser scanner) and sound-based sensors (sonar and radar). Ultrasonic transducers are one of the sound-based sensors, and they are more stable and reliable in environments where smoke or steam is present. Similar to human-made ultrasonic transducers, bats have developed highly capable biosonar systems that consist of one ultrasonic emitter (nose or mouth) and two ultrasonic receivers (ears), and these biosonar systems enable them to fly and hunt in cluttered environments. Some bats, e.g. rhinolophid and hipposiderid bats, have dynamic noseleaves (elaborate baffle shapes surrounding the nostrils) and pinna (outer ear), and these could enhance the sensing abilities of bats. Hence, the purpose of this thesis has been to investigate this variability to improve the human-made sensors by focusing on the dynamic pinna of the bats. It has been shown that bats have two distinct categories of pinna motions: rigid motions which change only the orientation of the pinna, and non-rigid motions which change also the shape of the pinna. However, the variability within the rigid and non-rigid pinna motions has received little attention. Therefore, the present work has investigated the variability in the rigid pinna motions and in the non-rigid pinna motions. Landmark points were placed on the pinna of certain bats and the pinna motions were tracked by high-speed video cameras. The rigid pinna motions exhibit a large continuous variation in where the pinna is orientated during rotation. Distributions of clusters of the landmarks on the pinna have shown that the non-rigid pinna motions fall into at least two subgroups. The acoustic impacts of the rigid pinna motions have been studied by a biomimetic pinna which reproduced the observed range of the rigid pinna motions. Ultrasonic signals mimicking the bats were emitted to be received by the biomimetic pinna. Based on these signals, it has been shown that different rotation axes and even small changes can provide over 50% new sensory information. These findings give engineers a potential way to improve the human-made sensors.

La especie endémica Pinna nobilis (Linnaeus, 1758) es el mayor bivalvo del mar Mediterráneo y uno de los mayores del mundo, pudiendo tener un tamaño superior a 1 m de longitud. Las poblaciones de la especie se han visto reducidas durante las últimas décadas por diversas causas de origen antrópico. Actualmente, la situación de la especie es crítica en todo el Mediterráneo, como consecuencia de la mortalidad masiva producida por el protozoo parásito Haplosporidium pinnae. La gravedad es tal, que se considera que la mortalidad es del 100% en las poblaciones afectadas, habiendo sido declarada en España en el año 2019, como especie en peligro de extinción. La presente tesis doctoral tiene como objetivos principales evaluar el estado de las poblaciones de P. nobilis antes y después del evento de mortalidad masiva, así como el estudio de la influencia de las variables ambientales sobre la actividad de las valvas de la especie. El estudio se llevó a cabo en la provincia de Alicante y de manera puntual, en estaciones de muestreo situadas en el resto de la Comunidad Valenciana. Se realizaron censos mediante equipo de buceo autónomo, comprobándose como, antes del evento de mortalidad, iniciado a finales de 2016, la densidad y distribución de tallas dependieron de los factores ambientales de cada localidad. A finales del año 2018 la mortalidad detectada fue del 100 % y se comprobó como la dispersión de los efectos causados por el protozoo se produjo de sur a norte de la Comunidad Valenciana. Para el estudio de la influencia de los factores ambientales en P. nobilis, se diseñó y fabricó un sistema de monitorización específico y se desarrolló un experimento de seguimiento in situ con seis individuos durante dos años. Las nacras estuvieron sincronizadas la mayor parte del tiempo y revelaron dos patrones estacionales de actividad, mostrando especial sensibilidad a las corrientes con dirección bimodal, como las producidas por las olas. Parte del presente trabajo de tesis doctoral se incluye dentro del concepto Ciencia Ciudadana, demostrando como los voluntarios con la formación, medios necesarios y supervisión adecuada, pueden obtener datos científicos de calidad.

Bats are a paragon of evolutionary success. They rely on parsimonious sensory inputs provided by echolocation, yet are able to master lives in complex environments. The outer ears (pinnae) of bats are intricately shaped receiver baffles that encode sensory information through a diffraction process. In some bat species with particularly sophisticated biosonar systems, such as horseshoe bats (Rhinolophidae), the pinnae are characterized by static as well as dynamic geometrical features. Furthermore, bats from these species can deform their pinnae while the returning ultrasonic waves impinge on them. Hence, these dynamic pinna geometries could be a substrate for novel, dynamic sensory encoding paradigms. In this dissertation, two aspects of this dynamic sensing process were investigated: (i) Do local shape features impact the acoustic effects during dynamic deformation of the bat pinna? and (ii) do these shape deformations provide a substrate for the dynamic encoding of sensory information? For this, a family of simplified biomimetic prototypes has been designed based on obliquely truncated cones manufactured from sheets of isobutyl rubber. These prototypes were augmented with biomimetic local shape features as well as with a parsimonious deformation mechanism based on a single linear actuator. An automated setup for the acoustic characterization of the time-variant prototype shapes has been devised and used to characterize the acoustic responses of the prototypes as a function of direction. It was found that the effects of local shape features did interact with each other and with the deformation of the overall shape. The impact of the local features was larger for bent than for upright shape configurations. Although the tested devices were much simpler than actual bat pinnae, they were able to reproduce numerical beampattern predictions that have been obtained for deforming horseshoe bat pinnae in a qualitative fashion. The dynamically deformable biomimetic pinna shapes were estimated to increase the sensory encoding capacity of the device by unit[80]{%} information when compared to static baffles. To arrive at this estimate, spectral clustering was used to break up the direction- and deformation-depended device transfer function into a discrete signal alphabet. For this alphabet, we could estimate the joint signal entropy across a bending cycle as a measure for sensory coding capacity. The results presented in this thesis suggest that bat biosonar posses unique dynamic sensing abilities which have no equivalent in man-made technologies. Sensing paradigms derived from bat biosonar could hence inspire new deformable wave-diffracting structures for the advancement in sensor technology. / Ph. D.

Many animal species are known for their unparalleled abilities to encode sensory information that supports fast, reliable action in complex environments, but the mechanisms remain often unclear. Through fast ear motions, bats can encode information on target direction into time-frequency Doppler signatures. These species were thought to be evolutionarily tuned to Doppler shifts generated by a prey's wing beat. Self-generated Doppler shifts from the bat's own flight motion were for the most part considered a nuisance that the bats compensate for. My findings indicate that these Doppler-based biosonar systems may be more complicated than previously thought because the animals can actively inject Doppler shifts into their input signals. The work in this dissertation presents a novel nonlinear principle for sensory information encoding in bats. Up to now, sound-direction finding has required either multiple signal frequencies or multiple pressure receivers. Inspired by bat species that add Doppler shifts to their biosonar echoes through fast ear motions, I present a source-direction finding paradigm based on a single frequency and a single pressure receiver. Non-rigid ear motions produce complex Doppler signatures that depend on source direction but are difficult to interpret. To demonstrate that deep learning can solve this problem, I have combined a soft-robotic microphone baffle that mimics a deforming bat ear with a CNN for regression. With this integrated cyber-physical setup, I have able to achieve a direction-finding accuracy of 1 degree based on a single baffle motion. / Doctor of Philosophy / Bats are well-known for their intricate biosonar system that allow the animals to navigate even the most complex natural environments. While the mechanism behind most of these abilities remains unknown, an interesting observation is that some bat species produce fast movements of their ears when actively exploring their surroundings. By moving their pinna, the bats create a time-variant reception characteristic and very little research has been directed at exploring the potential benefits of such behavior so far. One hypothesis is that the speed of the pinna motions modulates the received biosonar echoes with Doppler-shift patterns that could convey sensory information that is useful for navigation. This dissertation intends to explore this hypothetical dynamic sensing mechanism by building a soft-robotic biomimetic receiver to replicate the dynamics of the bat pinna. The experiments with this biomimetic pinna robot demonstrate that the non-rigid ear motions produce Doppler signatures that contain information about the direction of a sound source. However, these patterns are difficult to interpret because of their complexity. By combining the soft-robotic pinna with a convolutional neural network for processing the Doppler signatures in the time-frequency domain, I have been able to accurately estimate the source direction with an error margin of less than one degree. This working system, composed of a soft-robotic biomimetic ear integrated with a deep neural net, demonstrates that the use of Doppler signatures as a source of sensory information is a viable hypothesis for explaining the sensory skills of bats.