Effect of sound-induced vibrations of the pinna on head-related transfer functions: Experimental and numerical investigations.

Numerical simulations of head-related transfer functions (HRTFs) conventionally assume a rigid boundary condition for the pinna. The human pinna, however, is an elastic deformable body that can vibrate due to incident acoustic waves. This work investigates how sound-induced vibrations of the pinna can affect simulated HRTF magnitudes. The work will motivate the research question by measuring the sound-induced vibrational patterns of an artificial pinna with a high-speed holographic interferometric system. Then, finite element simulations are used to determine HRTFs for a tabletop model of the B&K 5128 head and torso simulator for a number of directions. Two scenarios are explored: one where the pinna is modeled as perfectly rigid, and another where the pinna is modeled as linear elastic with material properties close to that of auricular cartilage. The findings suggest that pinna vibrations have negligible effects on HRTF magnitudes up to 5 kHz. The same conclusion, albeit with less certainty, is drawn for higher frequencies. Finally, the importance of the elastic domain's material properties is emphasized and possible implications for validation studies on dummy heads 1as well as the limitations of the present work are discussed in detail.

Externalization of remote microphone signals using a structural binaural model of the head and pinna.

In a remote microphone (RM) system, a talker speaks into a microphone and the signal is transmitted to the hearing aids worn by the hearing-impaired listener. A difficulty with remote microphones, however, is that the signal received at the hearing aid bypasses the head and pinna, so the acoustic cues needed to externalize the sound source are missing. The objective of this paper is to process the RM signal to improve externalization when listening through earphones. The processing is based on a structural binaural model, which uses a cascade of processing modules to simulate the interaural level difference, interaural time difference, pinna reflections, ear-canal resonance, and early room reflections. The externalization results for the structural binaural model are compared to a left-right signal blend, the listener's own anechoic head-related impulse response (HRIR), and the listener's own HRIR with room reverberation. The azimuth is varied from straight ahead to 90° to one side. The results show that the structural binaural model is as effective as the listener's own HRIR plus reverberation in producing an externalized acoustic image, and that there is no significant difference in externalization between hearing-impaired and normal-hearing listeners.

Reevaluation of the arterial blood supply of the auricle.

The anatomical basis for auricular flaps used in multiple aesthetic and reconstructive procedures is currently based on a random distribution of the underlying arterial network. However, recent findings reveal a systematic pattern as opposed to the present concepts. Therefore, we designed this study to assess the arterial vascular pattern of the auricle in order to provide reliable data about the vascular map required for surgical interventions. Sixteen human auricles from eight body donors (five females/three males, 84.33 ± 9.0 years) were investigated using the unique 'Spalteholz' method. After arterial injection of silicone, a complete transparency of the tissue was achieved and the auricular arteries and branches were visible. Qualitative and quantitative evaluation of the arterial vascular pattern was performed. The superior and the inferior anterior auricular artery provided the vascular supply to the helical rim, forming an arcade, i.e. helical rim arcade. On the superior third of the helical rim another arcade was confirmed between the superior anterior auricular artery and the posterior auricular artery (PAA), i.e. the helical arcade. The perforators of the PAA were identified lying in a vertical line 1 cm posterior to the tragus, supplying the concha, inferior crus, triangular fossa, antihelix and the earlobe. The results of this study confirmed the constant presence of the helical rim arcade (Zilinsky-Cotofana), consistent perforating branches of the PAA, and the helical arcade (Erdman), and will help and guide physicians performing auricular surgeries toward fast and simple procedures with optimal patient satisfaction.

Horseshoe bats and Old World leaf-nosed bats have two discrete types of pinna motions.

Horseshoe bats (Rhinolophidae) and the related Old World leaf-nosed bats (Hipposideridae) both show conspicuous pinna motions as part of their biosonar behaviors. In the current work, the kinematics of these motions in one species from each family (Rhinolophus ferrumequinum and Hipposideros armiger) has been analyzed quantitatively using three-dimensional tracking of landmarks placed on the pinna. The pinna motions that were observed in both species fell into two categories: In "rigid rotations" motions the geometry of the pinna was preserved and only its orientation in space was altered. In "open-close motions" the geometry of the pinna was changed which was evident in a change of the distances between the landmark points. A linear discriminant analysis showed that motions from both categories could be separated without any overlap in the analyzed data set. Hence, bats from both species have two separate types of pinna motions with apparently no transitions between them. The deformations associated with open-close pinna motions in Hipposideros armiger were found to be substantially larger compared to the wavelength associated with the largest pulse energy than in Rhinolophus ferrumequinum (137% vs 99%). The role of the two different motions in the biosonar behaviors of the animals remains to be determined.

The Existence of a Natural Plica at the Anatomical Base of the Antihelix and its Surgical Importance to Address Protruding Ears: An Anatomicosurgical Study.

BACKGROUND: Protruding ears represent the main abnormality of the external ear, which has required numerous anatomic and surgical studies. Most studies give attention to the absence of the antihelix as the anatomic defect responsible for the clinical deformity of the lateral aspect of the ear that leads to its anteversion. The reason for this study is the controversial origin of the fold of the antihelix within the auricle framework, a field of interest for aesthetic otoplasty. The current study examined the medial surface of the cartilaginous ear frame from cadaver specimens with right morphology to investigate the starting point of the fold of the antihelix. This allowed for verification of a natural plica at the anatomic base of this antihelical fold, which to date has not had its topography described morphologically. It is acknowledged that relevant literature makes no reference to this innominate natural plica at the origin of the antihelix, whose anatomic and surgical importance is related in this report. This study aimed to show that the existence of a natural plica at the base of the antihelix in ear framing represents a landmark between normal and protruding ear morphology. METHODS: For 8 years, 118 ears were carefully investigated within rigid ethical principles based on a thorough review of the pertinent literature. The study investigated 16 selected cadaver specimens and 102 protruding ears dissected by the senior author including 49 bilateral cases (26 males and 23 females) and 4 unilateral cases (2 males and 2 females). Bifacial anthropometric measurements by calipers were used for documentation. RESULTS: A natural plica at the base of the antihelix was found in all cadaver ears selected with right morphology, whereas it was totally absent in every surgically treated protruding ear irrespective of color, gender, age, or ethnic origin. Ambilateral measures of the antihelix eminence certify the study object in normal specimens as well as its lack in abnormal ones. CONCLUSION: Technical and topographic knowledge that a natural plica exists at the anatomic base of the antihelix is a valuable key point in recognizing the normal external ear. In addition, the making of a natural plica is the first and most effective factor in the reconstruction of the antihelical fold and its absolute absence results in the pathologic condition for protruding ears. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the A3 online Instructions to Authors. http://www.springer.com/00266 .

An Evaluation of Benchmarks for Esthetic Orientation of the Occlusal Plane.

PURPOSE: This patient study was designed to measure the validity of both the horizontal and Camper's planes, which are used as benchmarks to reestablish the sagittal orientation of the occlusal plane angles in dental rehabilitation. MATERIALS AND METHODS: Profile digital photographs were made of the first 100 consenting dentate patients as they closed on an occlusal plane analyzer while maintaining natural head posture. Using a digital screen protractor, three angles were measured: the occlusal plane angle relative to the horizontal plane, and the angle between the occlusal plane and Camper's plane from both the superior and inferior borders of the tragus of the ear. RESULTS: The angle between the occlusal plane and the horizontal reference plane for the 100 patients ranged from -8.72° to +18.08° (mean +3.25°); the angle between the occlusal plane and Camper's plane, from the superior border of the tragus to the ala of the nose demonstrated a range from -8.49° to +15.16° (mean +3.03°); and the angle between Camper's plane, from the inferior border of the tragus to the ala of the nose and the occlusal plane demonstrated a range from -15.57° to +9.15° (mean -4.09°). CONCLUSIONS: Occlusal plane angles measured in this patient population with natural dentitions demonstrated a relatively small mean deviation from both the horizontal plane and Camper's plane when using the superior border of the tragus as the distal reference point, but the range was quite broad and could result in unacceptable occlusal plane angles in many patients undergoing dental rehabilitation. CLINICAL IMPLICATIONS: Both Camper's plane and the horizontal reference plane may be acceptable initial reference planes for oral rehabilitation, but additional anatomic and esthetic parameters are required for verification of an esthetically pleasing occlusal plane angle.

Did Dumbo suffer a heart attack? independent association between earlobe crease and cardiovascular disease.

BACKGROUND: Earlobe crease (ELC) has been associated with cardiovascular diseases (CVD) or risk factors (CVRF) and could be a marker predisposing to CVD. However, most studies studied only a small number of CVRF and no complete assessment of the associations between ELC and CVRF has been performed in a single study. METHODS: Population-based study (n = 4635, 46.7% men) conducted between 2009 and 2012 in Lausanne, Switzerland. RESULTS: Eight hundred six participants (17.4%) had an ELC. Presence of ELC was associated with male gender and older age. After adjusting for age and gender (and medication whenever necessary), presence of ELC was significantly (p < 0.05) associated with higher levels of body mass index (BMI) [adjusted mean ± standard error: 27.0 ± 0.2 vs. 26.02 ± 0.07 kg/m(2)], triglycerides [1.40 ± 0.03 vs. 1.36 ± 0.01 mmol/L] and insulin [8.8 ± 0.2 vs. 8.3 ± 0.1 µIU/mL]; lower levels of HDL cholesterol [1.61 ± 0.02 vs. 1.64 ± 0.01 mmol/L]; higher frequency of abdominal obesity [odds ratio and (95% confidence interval) 1.20 (1.02; 1.42)]; hypertension [1.41 (1.18; 1.67)]; diabetes [1.43 (1.15; 1.79)]; high HOMA-IR [1.19 (1.00; 1.42)]; metabolic syndrome [1.28 (1.08; 1.51)] and history of CVD [1.55 (1.21; 1.98)]. No associations were found between ELC and estimated cardiovascular risk, inflammatory or liver markers. After further adjustment on BMI, only the associations between ELC and hypertension [1.30 (1.08; 1.56)] and history of CVD [1.47 (1.14; 1.89)] remained significant. For history of CVD, further adjustment on diabetes, hypertension, total cholesterol and smoking led to similar results [1.36 (1.05; 1.77)]. CONCLUSION: In this community-based sample ELC was significantly and independently associated with hypertension and history of CVD.

Vertical normal modes of human ears: Individual variation and frequency estimation from pinna anthropometry.

Beyond the first peak of head-related transfer functions or pinna-related transfer functions (PRTFs) human pinnae are known to have two normal modes with "vertical" resonance patterns, involving two or three pressure anti-nodes in cavum, cymba, and fossa. However, little is known about individual variations in these modes, and there is no established model for estimating their center-frequencies from anthropometry. Here, with geometries of 38 pinnae measured, PRTFs were calculated and vertical modes visualized by numerical simulation. Most pinnae were found to have both Cavum-Fossa and Cavum-Cymba modes, with opposite-phase anti-nodes in cavum and either fossa or cymba, respectively. Nevertheless in both modes, fossa involvement varied substantially across pinnae, dependent on scaphoid fossa depth and cymba shallowness. Linear regression models were evaluated in mode frequency estimation, with 3322 measures derived from 31 pinna landmarks. The Cavum-Fossa normal mode frequency was best estimated [correlation coefficient r = 0.89, mean absolute error (MAE) = 257 Hz or 4.4%] by the distance from canal entrance to helix rim, and cymba horizontal depth. The Cavum-Cymba normal mode frequency was best estimated (r = 0.92, MAE = 247 Hz or 3.2%) by the sagittal-plane distance from concha floor to cymba anterior wall, and cavum horizontal depth.

Influence of voxelization on finite difference time domain simulations of head-related transfer functions.

The scattering around the human pinna that is captured by the Head-Related Transfer Functions (HRTFs) is a complex problem that creates uncertainties in both acoustical measurements and simulations. Within the simulation framework of Finite Difference Time Domain (FDTD) with axis-aligned staircase boundaries resulting from a voxelization process, the voxelization-based uncertainty propagating in the HRTF-captured sound field is quantified for one solid and two surface voxelization algorithms. Simulated results utilizing a laser-scanned mesh of Knowles Electronics Manikin for Acoustic Research (KEMAR) show that in the context of complex geometries with local topology comparable to grid spacing such as the human pinna, the voxelization-related uncertainties in simulations emerge at lower frequencies than the generally used accuracy bandwidths. Numerical simulations show that the voxelization process induces both random error and algorithm-dependent bias in the simulated HRTF spectral features. Frequencies fr below which the random error is bounded by various dB thresholds are estimated and predicted. Particular shortcomings of the used voxelization algorithms are identified and the influence of the surface impedance on the induced errors is studied. Simulations are also validated against measurements.

Modeling human echolocation of near-range targets with an audible sonar.

Blind humans echolocate nearby targets by emitting palatal clicks and perceiving echoes that the auditory system is not able to resolve temporally. The mechanism for perceiving near-range echoes is not known. This paper models the direct mouth-to-ear signal (MES) and the echo to show that the echo enhances the high-frequency components in the composite MES/echo signal with features that allow echolocation. The mouth emission beam narrows with increasing frequency and exhibits frequency-dependent transmission notches in the backward direction toward the ears as predicted by the piston-in-sphere model. The ears positioned behind the mouth detect a MES that contains predominantly the low frequencies contained in the emission. Hence the high-frequency components in the emission that are perceived by the ears are enhanced by the echoes. A pulse/echo audible sonar verifies this model by echolocating targets from 5 cm range, where the MES and echo overlap significantly, to 55 cm. The model predicts that unambiguous ranging occurs over a limited range and that there is an optimal range that produces the highest range resolution.

The styloauricular muscle: clinical relevance and literature review of this rare muscle.

PURPOSE: In humans, the styloauricularis is a rare muscle extending from the tragal cartilage of the auricle to the styloid process. When it contracts, by bearing on the styloid process, it increases the cephalo-auricular angle. It can be a landmark for the facial nerve. We report a case with bilateral presence of the styloauricularis. METHODS: Bilateral presence of the styloauricularis was discovered during routine dissection of the head and neck. RESULTS: In the presented case, styloauricularis muscles arose from the cartilage of the external acoustic meatus on both sides of the head, crossing halfway along the facial nerve trunk and inserting the styloid process. Both muscles were vascularized by a branch of the posterior auricular artery, and innervated by the facial nerve. CONCLUSIONS: The ventral auricular muscle, formed by the auricular parotid and the styloauricular muscles, is a muscle that lowers and abducts the auricle in animals. There is generally considered to be no equivalent for these muscles in humans, however, this bilateral case reveals evidence to the contrary. There is a dearth of scientific literature about the styloauricularis. The study of this muscle demonstrated the usefulness of comparative anatomy in understanding its action in increasing the cephalo-auricular angle.

An investigation of matching symmetry in the human pinnae with possible implications for 3D ear recognition and sound localization.

The human external ears, or pinnae, have an intriguing shape and, like most parts of the human external body, bilateral symmetry is observed between left and right. It is a well-known part of our auditory sensory system and mediates the spatial localization of incoming sounds in 3D from monaural cues due to its shape-specific filtering as well as binaural cues due to the paired bilateral locations of the left and right ears. Another less broadly appreciated aspect of the human pinna shape is its uniqueness from one individual to another, which is on the level of what is seen in fingerprints and facial features. This makes pinnae very useful in human identification, which is of great interest in biometrics and forensics. Anatomically, the type of symmetry observed is known as matching symmetry, with structures present as separate mirror copies on both sides of the body, and in this work we report the first such investigation of the human pinna in 3D. Within the framework of geometric morphometrics, we started by partitioning ear shape, represented in a spatially dense way, into patterns of symmetry and asymmetry, following a two-factor anova design. Matching symmetry was measured in all substructures of the pinna anatomy. However, substructures that 'stick out' such as the helix, tragus, and lobule also contained a fair degree of asymmetry. In contrast, substructures such as the conchae, antitragus, and antihelix expressed relatively stronger degrees of symmetric variation in relation to their levels of asymmetry. Insights gained from this study were injected into an accompanying identification setup exploiting matching symmetry where improved performance is demonstrated. Finally, possible implications of the results in the context of ear recognition as well as sound localization are discussed.

The prominent antihelix and helix--the myth of the 'overcorrected' ear in otoplasty.

BACKGROUND: Classic teaching of ear anatomy in the context of otoplasty states that if the antihelical fold is more prominent than the helical fold after surgery then the ear is "overcorrected." We set out to explore the role of the antihelix in normal ear anatomy, its relevance to aesthetic perceptions of the ear, and a snapshot of its incidence in nonoperated ears. METHODS: To readily identify junior staff in our department, their color photographs, names, and contact details are posted on every ward. Using digital methods, we cropped the left ear out of the source images, making them unidentifiable. Clinical and nonclinical staff in our unit were asked to choose their favorite and their least favorite ears based on their aesthetic appeal. Responses were tabulated and the 2 most popular ears were compared. RESULTS: The preferred ear did not conform to the traditional dogma because it had a prominent antihelix and was statistically significant when compared to other choices. We also noted that a prominent antihelix is common among the general population and among colleagues within the department, and hence "normal." Also interesting was that the helix of the ear chosen as the most aesthetic was also the ear where the helix was almost touching the side of the head. CONCLUSIONS: We found that when judging the aesthetic nature of the "virgin" ear, antihelical fold prominence did not appear to be a negative attribute. Indeed, we noted that a prominent antihelix was a common attribute, and we conclude that this was a normal variant without undue negative aesthetic stigma. A surgically corrected ear should not necessarily be regarded as a poor outcome simply on the basis of antihelical prominence. Furthermore, we postulate that patients who have a prominent antihelix might be part of a spectrum of individuals who might have had the subtype of prominent ears featuring a deep conchal bowl. Finally, although not tested directly, it appears that we do not have an idea of our own ear shape, as none of the participants was able to recognize their own ear from the photographs.

Frequency and amplitude estimation of the first peak of head-related transfer functions from individual pinna anthropometry.

The first (lowest) peak of head-related transfer functions (HRTFs) is known to be a concha depth resonance and a spectral cue in human sound localization. However, there is still no established model to estimate its center-frequency F1 and amplitude A1 from pinna anthropometry. Here, with geometries of 38 pinnae measured and their median-plane HRTFs calculated by numerical simulation, linear regression models were evaluated in estimating F1 and A1 from 25 concha depth and aperture measurements. F1 was best estimated (correlation coefficient r = 0.84, mean absolute error MAE = 118 Hz) by lateral distances from the base of the posterior cavum concha to the outer surface of the antitragus and antihelix (longest measures of concha depth). A1 was best estimated (r = 0.83, MAE = 0.84 dB) by the lateral distance from the ear-canal entrance to the side of the cheek near the anterior notch (shortest measure of concha depth) and by the equivalent diameter of the concha aperture. These results suggest that the first resonance's quarter-wavelength corresponds to the longest lateral extent of the concha and that its energy lost to the surrounding air depends on the concha aperture and the cavum concha's shortest lateral depth.

Novel reconstructive methods of the conchal central strut using an absorbable plate after total harvesting of the conchal cartilage.

PURPOSE: Conchal cartilage is widely used in the field of plastic surgery, but donor-site morbidity is inevitable when all of the conchal cartilage is harvested. To maintain ear shape, the authors introduce a new method using an absorbable plate to reconstruct the conchal central strut after total harvesting of the conchal cartilage. METHODS: In total, 18 subjects underwent surgery, and 14 subjects who were followed up for more than 12 months were included in this article. Before the total harvesting of the conchae, an absorbable plate was adjusted to the proper curvature and length. After harvesting, the central strut was reconstructed by the precrafted absorbable plate. When the harvested cartilage was too large or one implant was not sufficient to reconstruct the central strut, an additional implant was added to the cymba conchae.Outcomes were evaluated by photogrammetry and questionnaires. Seven items were selected to evaluate the shape of the ear and conchal cavity. The authors compared preoperative and postoperative photographs, looking at proportion indices of 7 items using Photoshop. Ten assessors who did not participate in the operation were also shown preoperative and postoperative photographs and answered questionnaires about the shapes of the ear, conchal cavity, and conchal central strut. RESULTS: Except for the effective conchal cavity height index, no statistically significant differences were observed between preoperative and postoperative ear shapes. Additionally, the questionnaire showed excellent assessments for all items. CONCLUSIONS: Reconstruction of the central strut using an absorbable plate after total harvest of the conchal cartilage was a simple and effective method to prevent ear collapse.

Dynamometric Analysis of Normative Auricular Stiffness and Comparison With Operated Prominent Ears.

AIM: Stiffness of the auricular cartilage is the main determining factor for the choice of operative technique of the prominent ear deformity. The aim of this study is to evaluate the stiffness of normal appearing ears objectively and quantitatively, compare the results with the operated prominent ear patients, and present prospective short-term dynamometric evaluation of the operated prominent ear patients. PATIENTS AND METHODS: A total of 190 volunteers without ear deformities were recruited and 9 age groups were formed: group (5-9), group (10-14), group (15-19), group (20-24), group (25-29), group (30-34), group (35-39), group (40-49), and group (50+). Total 28 ears (14 patients) with otoplasty were included in the study as group (operated 5-9) and group (operated 10-14). In addition, 3 patients with prominent ear deformity were prospectively followed for dynamometric changes that occur with otoplasty operation. The auriculocephalic angle (ACA) was measured once and auricle to scalp distance was measured at 4 different standardized levels. Ear stiffness was measured on each ear individually at 4 different points over the antihelix using digital computer-aided dynamometry. Each ear was compared in terms of ACA, distance, and dynamometric values. FINDINGS: Dynamometric values tend to increase with age, which increase and peak around 35 years of age and declines after 40 years of age. Measurements of the first 2 age groups were statistically different compared with the other groups. Postoperative dynamometric measurements (DNM) of group (operated 5-9) were similar with normative values of group (5-9) and postoperative satisfaction visual analogue scale (VAS) score was 92.8%. Postoperative DNM of group (operated 10-14) were higher compared with normative values of group (10-14) for each different measuring level and the postoperative satisfaction VAS score was 75.3. A total of 3 patients with prominent ears had lower dynamometric values preoperatively; these values approached closer to normative values of their age group postoperatively. CONCLUSIONS: Results show that auricular cartilage stiffens and malleability decreases with increased age. This stiffness peaks in the 35-39 age group and declines after 40 years of age. Dynamometric values increase, at all levels, suggesting increased cartilage stiffness is related to age. In the scope of these results, cartilage sparing techniques are more suitable for 5 to 14 years of age and cartilage-cutting techniques are more suitable for older patients.

Personalization of head-related transfer functions in the median plane based on the anthropometry of the listener's pinnae.

A listener's own head-related transfer functions (HRTFs) are required for accurate three-dimensional sound image control. The HRTFs of other listeners often cause front-back confusion and errors in the perception of vertical angles. However, measuring the HRTFs of all listeners for all directions of a sound source is impractical because the measurement requires a special apparatus and a lot of time. The present study proposes a method for estimating the appropriate HRTFs for an individual listener. The proposed method estimates the frequencies of the two lowest spectral notches (N1 and N2), which play an important role in vertical localization, in the HRTF of an individual listener by anthropometry of the listener's pinnae. The best-matching HRTFs, of which N1 and N2 are the closest to the estimates, are then selected from an HRTF database. In order to examine the validity of the proposed method, localization tests in the upper median plane were performed using four subjects. The results revealed that the best-matching HRTFs provided approximately the same performance as the listener's own HRTFs for the target directions of the front and rear for all four subjects. For the upper target directions, however, the performance of the localization for some of the subjects decreased.

Internalized elevation perception of simple stimuli in cochlear-implant and normal-hearing listeners.

In normal-hearing (NH) listeners, elevation perception is produced by the spectral cues imposed by the pinna, head, and torso. Elevation perception in cochlear-implant (CI) listeners appears to be non-existent; this may be a result of poorly encoded spectral cues. In this study, an analog of elevation perception was investigated by having 15 CI and 8 NH listeners report the intracranial location of spectrally simple signals (single-electrode or bandlimited acoustic stimuli, respectively) in both horizontal and vertical dimensions. Thirteen CI listeners and all of the NH listeners showed an association between place of stimulation (i.e., stimulus frequency) and perceived elevation, generally responding with higher elevations for more basal stimulation. This association persisted in the presence of a randomized temporal pitch, suggesting that listeners were not associating pitch with elevation. These data provide evidence that CI listeners might perceive changes in elevation if they were presented stimuli with sufficiently salient elevation cues.

The ala-tragus line as a guide for orientation of the occlusal plane in complete dentures.

AIM: The use of the ala-tragus line (ATL) to orient the occlusal plane (OP) is controversial because there is a lack of agreement on the exact points of reference for this line. This study determined the relationship between the natural OP and ATL which was established by using the inferior border of the ala of the nose and (1) the superior border of the tragus (ATL1), (2) the tip (ATL2), and (3) the inferior border of the tragus (ATL3). MATERIALS AND METHODS: Lateral cephalometric radiographs were taken of each subject by a standard method and tracings were obtained on acetate paper to show the OP and the three ala-tragus lines. The relationship between the OP and each of ATL was measured for each subject. Mean and standard deviation values were then calculated for the relationship. Statistical analysis was performed using repeated measure analysis of variance followed by Bonferroni pairwise comparisons and Student's t-test (α = 0.05). RESULTS: Significant differences were noted between the three mean angles (p = 0.046). The mean angle (3.275 degrees ± 2.54) formed by OP and ATL2 was significantly the smallest (p < 0.05). CONCLUSION: The ala-tragus line, extending from the inferior border of the ala of the nose to the tip of the tragus of the ear presented the closest relationship to the natural occlusal plane.

A three-dimensional algorithm for precise measurement of human auricle parameters.

Measurement of auricle parameters for planning and post-operative evaluation presents substantial challenges due to the complex 3D structure of the human auricle. Traditional measurement methods rely on manual techniques, resulting in limited precision. This study introduces a novel automated surface-based three-dimensional measurement method for quantifying human auricle parameters. The method was applied to virtual auricles reconstructed from Computed Tomography (CT) scans of a cadaver head and subsequent measurement of important clinically relevant aesthetical auricular parameters (length, width, protrusion, position, auriculocephalic angle, and inclination angle). Reference measurements were done manually (using a caliper and using a 3D landmarking method) and measurement precision was compared to the automated method. The CT scans were performed using both a contemporary high-end and a low-end CT scanner. Scans were conducted at a standard scanning dose, and at half the dose. The automatic method demonstrated significantly higher precision in measuring auricle parameters compared to manual methods. Compared to traditional manual measurements, precision improved for auricle length (9×), width (5×), protrusion (5×), Auriculocephalic Angle (5-54×) and posteroanterior position (23×). Concerning parameters without comparison with a manual method, the precision level of supero-inferior position was 0.489 mm; and the precisions of the inclination angle measurements were 1.365 mm and 0.237 mm for the two automated methods investigated. Improved precision of measuring auricle parameters was associated with using the high-end scanner. A higher dose was only associated with a higher precision for the left auricle length. The findings of this study emphasize the advantage of automated surface-based auricle measurements, showcasing improved precision compared to traditional methods. This novel algorithm has the potential to enhance auricle reconstruction and other applications in plastic surgery, offering a promising avenue for future research and clinical application.