Bat Ears Research Articles

Bat Ear Correction Steps and Outcomes for Better Life Support.

An unusually projecting human ear is known as a prominent ear, otapostasis, or bat ear. It might be both bilateral and unilateral. The scapha and antihelix of the big concha are not well formed. It is the outcome of cartilage deformity that occurred during early ear development in utero. After the child reaches five years old, the abnormality can be corrected at any time. In order to prevent psychological suffering, the procedure should ideally be performed as soon as possible. Otoplasty correction is reshaping the ear cartilage to bring the ear closer to the side of the head. The cartilage is reshaped, but the skin is left in place. Hearing remains unaffected by the operation. It is mainly done for aesthetic reasons. Although they are uncommon, the post-operative consequences from the operation include hematoma development, keloid formation, infection, and asymmetry in the ears. Otoplasty is a cosmetic operation that involves permanent sutures to alter the size, shape, or location of the ear. The main purpose of otoplasty is to treat promin auris, or bulging ears. Promin auris, the principal indication for otoplasty, is the subject of this review. The indications, contraindications, and method utilized in otoplasty are reviewed in this exercise, which also emphasizes the need of pre- and post-operative care for patients having this surgery. Otoplasty results are generally lifelong and will improve the self-confidence. The goals of otoplasties are to make the ears appear more natural in comparison to the head and help with the overall contour of the ears. Final ear surgery results will be visible after a two week recovery period, with small improvements appearing for up to 12 months post-procedure. A proper understanding of the diagnosis, indications, and surgical techniques will lead to positive outcomes in otoplasty.

Measuring and analyzing sound using phone microphone and free software

In Fall 2022 acoustics class, the students developed class projects using their smart phones to measure sound. In a laboratory exercise, the phones were calibrated against a standard microphone. A microphone circuit was bread boarded and calibrated to demonstrate the inner workings of electret microphone technology. Students developed projects around the measurement of sound, including measuring striking a cymbal, analyzing piano chords, analyzing guitar chords, characterizing reverberation time in a warehouse, and determining the amplification from a 3D printed human ear and bat ear. The sound files from the phone were edited to isolate the relevant sound and converted to WAV files using Garageband software. The WAV files were imported into Python for post-processing, such as windowing, filtering, and FFT. Most projects used a waterfall plot to demonstrate some time-frequency analysis. The ease with which the students mastered sound measurement and processing led to unexpectedly mature projects. The low cost of the equipment makes this approach a widely deployable educational paradigm.

The quest for the biosonar image of the world

The large differences in the wavelength of visible light and the ultrasonic pulses of bat biosonar raise the question whether the sensory world of bats is the same as that of humans and other visual animals, completely different, or something in-between. Pioneering research on this question has focused on the range dimension of biosonar perception exploiting the straightforward relationship between echo delay and target range. Furthermore, since bat ears are typically no more than a single order of magnitude longer than the respective ultrasonic wavelengths, the beam patterns of the animals are fairly wide, which can be expected to result in a much better resolution for range than along the cross-range dimension. Bats that use their biosonar to navigate in densely vegetated environments receive echoes containing contributions from many unresolved scatterers, i.e., “clutter echoes.” Extracting useful information from clutter has been studied using real-world data collected with biomimetic sonar systems and analyzed with deep-learning methods. The results demonstrate that useful information can be extracted from clutter echoes without the formation of an image, i.e., without a systematic spatial representation of resolved objects. Hence, many interesting aspects of how bats experience their sensory worlds may still be left to be discovered.

External Ears in Chiroptera: Form-Function Relationships in an Ecological Context

External ears in mammals direct and enhance perception of sound. In bats, where navigation and foraging are strongly contingent on reception of sound, we would expect correlations between bat external ear morphology and echolocation signal structure, acoustic and aerodynamic properties, and foraging strategies. Using Web search engines, we collected peer-reviewed literature on these relationships, with the aim of summarising the knowledge on these correlations and establishing general form-function patterns. The literature on the relationship echolocation-ear, and foraging strategy was scant (six and ten publications, respectively). Fifteen more examined the aerodynamic properties and 46 the acoustic properties. Because of the complexity of the subject, few attempts exist that examine ear properties (acoustic, aerodynamic, shape) at the same time for more than a few species. The number of species so far examined represents less than 15% of the total number of species of bats. Although the available information did not allow to propose general patterns of morphological response of external ears to the factors examined, our findings suggested that further analyses of the relationship form-function in bat ears should consider the study of ears as integrated, multivariate morphological entities in which shape, aerodynamic characteristics, and acoustic properties, are an integrated, multivariate whole that ultimately contributes to the bat foraging behaviour.

Otoplasty: a graduated approach

BackgroundBat ear deformity is a common presentation among the ENT patients (22.5%). Many surgical procedures have been described to manage such a problem. A thorough study of the anatomical anomalies contributing to such deformity is required by any plastic surgeon in handling this anomaly.ResultsModified anterior scoring (Chong-Chet) was done on 45 bat ear deformities in 31 patients. Good surgical results were obtained in 97.7% of patients, and the surgical time ranged from 60 t0 90 min. Postoperative pain and infection were minimal and effectively managed.ConclusionsThe modified Chong-Chet anterior scoring is a reliable and effective surgical tool for managing bat ear deformity done through one postauricular incision. This technique could be used in young as well as adult patients because it renders the auricular cartilage easier to manipulate.

The external ear morphology and presence of tragi in Australian marsupials.

Multiple studies have described the anatomy and function of the external ear (pinna) of bats, and other placental mammals, however, studies of marsupial pinna are largely absent. In bats, the tragus appears to be especially important for locating and capturing insect prey. In this study, we aimed to investigate the pinnae of Australian marsupials, with a focus on the presence/absence of tragi and how they may relate to diet. We investigated 23 Australian marsupial species with varying diets. The pinnae measurements (scapha width, scapha length) and tragi (where present) were measured. The interaural distance and body length were also recorded for each individual. Results indicated that all nectarivorous, carnivorous, and insectivorous species had tragi with the exception of the insectivorous striped possum (Dactylopsila trivirgata), numbat (Myrmecobius fasciatus), and nectarivorous sugar glider (Petaurus breviceps). No herbivorous or omnivorous species had tragi. Based on the findings in this study, and those conducted on placental mammals, we suggest marsupials use tragi in a similar way to placentals to locate and target insectivorous prey. The Tasmanian devil (Sarcophilus harrisii) displayed the largest interaural distance that likely aids in better localization and origin of noise associated with prey detection. In contrast, the smallest interaural distance was exhibited by a macropod. Previous studies have suggested the hearing of macropods is especially adapted to detect warnings of predators made by conspecifics. While the data in this study demonstrate a diversity in pinnae among marsupials, including presence and absence of tragi, it suggests that there is a correlation between pinna structure and diet choice among marsupials. A future study should investigate a larger number of individuals and species and include marsupials from Papua New Guinea, and Central and South America as a comparison.

The Role of Anterior Subperichondrial Rasping in Antihelixoplasty of Prominent Ears

The Role of Anterior Subperichondrial Rasping inAntihelixoplasty of Prominent EarsBackground: Prominent ears also known as Bat ears is acommon ear deformity that can cause emotional problems tothe individual involved. Various techniques have been describedeach with its advantages and disadvantages.Aim of Work: The aim of otoplasty is reducing the cephaloauricularangle to 15-20 degrees, emphasis on the antihelicalfold with a smooth helical rim, concha reduction and lobulopexy.Each ear is analyzed individually regarding its problemareas and the appropriate surgical approach with least possiblemorbidity is used.Material and Methods: In this study, five patients wereoperated upon in Kasr Al-Aini Hospital between October2015 to September 2016. The authors preferred technique forsuperior crus and antihelix formation was combined anteriorsubperichondrial rasping through an ventral incision withposterior transverse mattress 3/0 polyester (Ethibond) sutureson round body needle.Conclusion: This technique is easy, efficient with satisfactoryoutcome, could be done in most patients of variousages with minimal or absent complication rate.

Sonar signal representation mimicking the inner ear of horseshoe bats

Current models of the initial stages of auditory processing in mammals usually agree that the input signals are split into a bank of bandpass filters. However, the available models differ substantially in their level of complexity and the number of parameters needed. In the current work, the varying levels of complexity in filterbank models of the basilar membrane have been evaluated in the context of modeling the cochlear processing of natural biosonar echoes in horseshoe bats. To this end, three different types of filterbank models have been implemented to represent the range of complexity spanned by models that are in use for the human inner ear: The simplest model, a gammatone filterbank, is a linear model with symmetric filter transfer functions. The gammachirp filterbank is also linear, but mimics the asymmetric transfer functions of the basilar membrane. Finally, the dual resonance nonlinear (DRNL) model adds a level-dependent behavior. Here, all three models have been adapted to the specifics of the basilar membrane of horseshoe bats which is characterized by an “auditory fovea” with exceptionally high filter qualities. The outputs of the different models have been encoded into a sequence of neural spike times before being evaluated with various information-theoretic methods.

Hipposideros pinna motion patterns as an inspiration for dynamic biomimetic sensing

Many bat species, e.g., among the horseshoe bats (Rhinolophidae) and Old-World roundleaf-nosed bats (Hipposideridae), have highly mobile pinnae. Experiments with biomimetic reproductions of the pinnae shapes/motion patterns in these species have demonstrated a dynamic enhancement of the performance in acoustic direction-finding paradigms. It could hence be hypothesized that reproducing the full range of pinna mobility patterns in bats will allow realizing the full range of the animals' biosonar capabilities. Pinna motions in rhinolophid and hipposiderid bats have been shown to fall into two distinct categories, being either rigid rotations (i.e., changes in orientation but not in the shape itself) or deformations that change both pinna orientation and shape. To characterize the variability in the rigid rotations, landmarks on the pinnae of hipposiderid bats have been tracked using stereovision. From this kinematics data, an axis-angle representation of the pinna rotations was estimated. The results showed that the axes of pinna rotations can scatter widely in orientation, covering a range of directions that extends 180 degrees in azimuth and 180 degrees in elevation, about 40 times larger than the estimated error of the employed method. Hence, biomimetic reproductions of bat ear mobility should explore how to make use of such a variability.

Correction of prominent ear by the two parallel incision technique with definition and folding of the antihelix by vertical mattress sutures

BackgroundMultiple techniques have been advocated over the years for correction of the prominent ear. The basic techniques used to correct prominent ears with a missing antihelix depends on incision, scoring, bending and reposition of the auricular cartilages. This study was undertaken to correct prominent ears using cartilage incision and vertical mattress sutures to define antihelix.Patients and MethodsThis study was carried out on 13 patients (25 ears) in the period between February 2014 and June 2017, twelve patients of them were presented with bilateral prominent ears and one patient was presented with unilateral prominent (bat) ear. This series comprised 8 males and 5 females. Their ages ranged between 7 to 33 years. In this technique 2 parallel incision in auricular cartilage, definition of antihelix with vertical mattress sutures and ellipse of skin was removed.ResultsSatisfactory results were obtained in all patients. Complications occurred in 2 patients only: one of them had mild protrusion of upper third of auricle and the other had keloid.ConclusionOur technique produces natural-looking of the operated ears with low complication rates.

Helix free otoplasty for correction of prominent ear

Prominent or bat ear is not uncommon deformity as it affecting 5% of population. Plenty of procedures were reported for its correction. Being plenty means it is still a subject of research. The current procedures could be summarized as cartilage sparing and cartilage splitting ones. During a period of 35 months a total of 31 patients were presented with bilateral prominent ears so the included a total of 62 ears. Their average age was 8 years (ranging from five to 18 years). All deformities were corrected using helix free otoplasty technique which included skin paddle excision, separation of helical cartilage (hence the name helix free), anterior scoring, backward folding, mattress and simple suturing of the folded cartilage, proper definition of antitragus and earlobe and concha-mastoid sutures. Outcomes including patient's and/or guardians' satisfaction were determined. The postoperative period was uneventful except two cases that developed early postoperative hematomas, one case shows late postoperative antihelical fold irregularity in one ear and other case developed ill defined superior helix in one ear. The average follow up period of two years shows no recurrences. Almost all patients (96.85%) and their guardians were satisfied with the aesthetic results while only one (3.2%) was dissatisfied. Helical free otoplasty technique addresses the deformity through a posterior approach with under vision correction. It has very low incidence of complications, high patient's satisfactions, no visible scars and no recurrences. It is a simple, short duration procedure, reliable and good option for correction of prominent ear.

Ridge number in bat ears is related to both guild membership and ear length.

The ears of many mammals have a set of uniformly spaced horizontal ridges that form groove arrays. Contact of coherent waves (e.g. acoustic waves) with a series of slits or grooves causes diffraction, which produces constructive and destructive interference patterns. Increases in signal strength will occur but will depend on the frequencies involved, the groove number and their separations. Diffraction effects can happen for a wide range of frequencies and wavelengths, but no array can diffract wavelengths greater than twice the groove separation, and it is for those wavelengths comparable in size with the groove separation that the effects are greatest. For example, when ridges in bat ears are 1 mm apart, the strongest influence will occur for a 1 mm wavelength which corresponds to a frequency of 343 kHz. If bats could use these wavelengths, it would help them to resolve objects or surface textures of about 0.5 mm. Given how critical acoustics are for bat function, we asked whether bats may be taking advantage of diffraction effects generated by the grooves. We hypothesize that groove number varies with bat foraging strategy. Examining 120 species, we found that groove number is related to both guild and ear length. Bats in guilds that glean prey items from foliage or ground have on average more grooves than bats in other guilds. Harmonics generated by echolocation calls are the most likely source for the wavelengths that would correspond to the groove separations. We apply the physical principles of wave reflection, diffraction, and superposition to support the hypothesis that acoustic responses generated from grooves may be useful to bats. We offer an explanation why some bat species do not have grooves. We also discuss the presence of groove arrays in non-echolocating Chiropterans, and five additional mammalian orders.

Comparative study between anterior and posterior scoring in otoplasty for bat ear

This study is meant to compare between anterior and posterior scoring techniques for the correction of prominent ear primarily in terms of cosmesis and patients’ satisfaction. We included 50 patients who were randomly assigned to anterior scoring (AS; 25 subjects with a total of 45 ears) or posterior score (PS; 25 subjects with a total of 47 ears). All patients were subjected to full history taking, general & local examinations and laboratory investigations. We analyzed the age, sex, surgical technique, the need for a second operation, type of anesthetics, additional procedures, follow-up, complications, and results. Both groups were comparable as regard patient characteristics, laterality of prominent ear, intra-operative and follow up measurements and complications. However, posterior scoring results in a high satisfaction rate with low morbidity. It was shown to be safe (low complication rate), simple and reliable intervention. Thus, we advocate posterior scoring during correction of prominent ears deformity.

Plecotus macrobullaris (Chiroptera: Vespertilionidae)

Plecotus macrobullaris (Kuzjakin, 1965) is a medium-sized chiropteran commonly called the alpine long-eared bat, and 1 of the 11 Palearctic species recognized in the genus Plecotus. It has the characteristic long ears of plecotine bats, and externally its most conspicuous diagnostic characteristic is the inverted triangular-shaped pad most individuals exhibit in the chin. It is distributed across the mountain environments in the southwestern and central regions of the Palearctic. It is the most abundant bat species in European alpine environments, although it can be also found at lower elevations. It roosts on both natural (rock crevices, caves, and scree deposits) and artificial shelters (buildings), and it mainly feeds on moths. P. macrobullaris is currently listed as “Least Concern” by the International Union for Conservation of Nature and Natural Resources, although actual population sizes and demographic trends are unknown.

Review of Microtia : A Focus on Current Surgical Approaches

A wide spectrum of anomalies may involve the auditory system. As a visible structure, auricular malformations constitute a great burden. A wide set of anomalies may affect the ear including the microtia spectrum, protruding ears (bat ear), constricted ear (Lop and Cup ears), Stahl ear, and cryptotia.In plastic surgery practice protruding ears and microtia are common presentations. Microtia literally means small ears. Microtia is a spectrum of anomalies of the auricle that range from disorganized remnant of cartilage attached to soft tissue lobule to complete absence of the ear (anotia). Ear reconstructive procedures has made in impact in the lives of these patients. The early attempts to surgically restore the ear in microtia was in 1920 using a rib cartilage. Up to 49% of microtia cases are associated with other anomalies or a known syndrome. The most common syndromic associations are hemifacial microsomia, Towens Brocks syndrome, Treacher Collins, Goldenhar and Nager syndrome. Oculo-auriculo-vertebral spectrum (OAVS). Generally, the ear can be retrieved by two possible methods: Surgical reconstruction using autologous or alloplastic cartilage and the use of prosthesis which could be adhesive or implant retained. Surgical reconstruction proved to be superior to other methods due to its longevity and less complications. The only limitation is the skill of the surgeon. Ear prosthesis are reserved for special cases including traumatic anotia in adults.

Echo-acoustic scanning with noseleaf and ears in phyllostomid bats.

The mammalian visual system is highly directional and mammals typically employ rapid eye movements to scan their environment. Both sound emission and hearing in echolocating bats are directional but not much is known about how bats use ear movements and possibly movements of the sound-emitting structures to scan space. Here, we investigated in a tightly controlled behavioural experiment how Phyllostomusdiscolor bats employ their echolocation system while being moved through differently structured environments: we monitored and reconstructed both a close-up of the facial structures in 3D, including the motile noseleaf and outer ears, and the sonar-beam of the bat while it was moved along reflectors. Despite the simple linear movement of the bats in the setup, the bats pointed their beam quite variably in azimuth with a standard deviation of about ±20deg. This variation arises from yaw-type head rotations. Video analyses show that the bat's noseleaf twitches with every echolocation call. Second, we show that the bat's ears are raised to a rather stereotypical head-centred position with every echolocation call. Surprisingly, P. discolor can adjust the timing and the magnitude of these ear movements to the distance of the reflectors with millisecond precision. Our findings reveal echolocation-specific specialisations as well as general principles of scanning and stabilisation of a directional remote sense. The call-correlated movements of the facial structures may lead to a higher directionality of the echolocation system and may enable the bats to adjust their echo-acoustic gaze to dynamic environments.

The relationship between pinna and noseleaf motions in hipposiderid bats

Old World leaf-nosed bats (Hipposideridae) are a family of bat species that use elaborate baffle shapes to diffract the outgoing ultrasonic pulses and the returning echoes. The baffles at both interfaces (“noseleaves” for emission, outer ears for reception) have dynamic geometries that can be changed through muscular actuation. Shape changes in noseleaves and pinnae can both coincide with sound emission and reception respectively, but the relationship between the dynamics in these two structures has yet to be investigated. To study this relationship, a set of no less than 17 landmarks was placed on the noseleaf and one ear of Pratt's roundleaf bats (Hipposideros pratti) to track the dynamic geometry of these structures simultaneously with a high-speed video camera array. The three-dimensional trajectories of the landmark points were reconstructed using stereovision. The results showed strong, systematic relationships between noseleaf and pinna motions that were found to belong to two different qualitative...

Directional Receiver for Biomimetic Sonar System

An ultrasonic localization method for a sonar system equipped with an emitter and two directional receivers and inspired by bat echolocation uses knowledge of the beam pattern of the receivers to estimate target orientation. Rousettus leschenaultii's left ear constitutes the model for the design of the optimal receiver for this sonar system and 3D printing was used to fabricate receiver structures comprising of two truncated cones with an elliptical external perimeter and a parabolic flare rate in the upper part. Measurements show one receiver has a predominant lobe in the same region and with similar attenuation values as the bat ear model. The final sonar system is to be mounted on vehicular and aerial robots which require remote control for motion and sensors for estimation of each robot's location.

Features in geometric receiver shapes modelling bat-like directivity patterns

The directional properties of bat ears as receivers is a current area of interest in ultrasound research. This paper presents a new approach to analyse the relationship between morphological features and acoustical properties of the external ear of bat species. The beam pattern of Rousettus leschenaultii's right ear is measured and compared to that of receiver structures whose design is inspired by the bat ear itself and made of appropriate geometric shapes. The regular shape of these receivers makes it possible to control the key reception parameters and thus to understand the effect on the associated beam pattern of the parameters themselves. Measurements show one receiver structure has a beam pattern very similar to that of R. leschenaultii's ear, thus explaining the function of individual parts constituting its ear. As it is applicable to all bat species, this approach can provide a useful tool to investigate acoustics in bats, and possibly other mammals.

Bat flight

Bat flight