Ear Impression Research Articles

A Novel Ear Impression-Taking Method Using Structured Light Imaging and Machine Learning: A Pilot Proof of Concept Study with Patients' Feedback on Prototype.

Taking an ear impression is a minimally invasive procedure. A review of existing literature suggests that contactless methods of scanning the ear have not been developed. We proposed to establish a correlation between external ear features with the ear canal and with this proof of concept to develop a prototype and an algorithm for capturing and predicting ear canal information. We developed a novel prototype using structured light imaging to capture external images of the ear. Using a large database of existing ear impression images obtained by traditional methods, correlation analyses were carried out and established. A deep neural network was devised to build a predictive algorithm. Patients undergoing hearing aid evaluation undertook both methods of ear impression-taking. We evaluated their subjective feedback and determined if there was a close enough objective match between the images obtained from the impression techniques. A prototype was developed and deployed for trial, and most participants were comfortable with this novel method of ear impression-taking. Partial matching of the ear canal could be obtained from the images taken, and the predictive algorithm applied for a few sample images was within good standard of error with proof of concept established. Further studies are warranted to strengthen the predictive capabilities of the algorithm and determine optimal prototype imaging positions so that sufficient ear canal information can be obtained for three-dimensional printing. Ear impression-taking may then have the potential to be automated, with the possibility of same-day three-dimensional printing of the earmold to provide timely access.

Comparison of Traditional Impression and 3D Ear Scanning Techniques, Earmold Comfort, and Audiology Clinical Implications: A Pilot Study.

This study investigated clinical aspects of the traditional ear impression and 3D ear scanning techniques. Adult earmold-users and non-users participated in this study. The earmold-users also participated in the earmold comfort comparison study by wearing earmolds from both techniques, one set a week according to a randomized sequence. Multiple clinical aspects of both techniques according to the participants and audiology professionals were recorded. Results revealed a preference for the 3D-scanning technique, which was perceived as more comfortable although both techniques were perceived as safe. Although the earmolds might have issues from both techniques, there was no significant difference in the perception of earmolds. Experience with the specific technique can affect the responses from the professionals. Compared to the traditional technique, 3D-scans had higher fixed but less variable costs and procedure times. A special clinical case was included and indicated that 3D-scans could be an option for specific patients. This study led to a better understanding of the two techniques clinically. With increasing involvement of new technology and more young professionals joining the profession of audiology, 3D ear scanning could be a viable consideration for audiology practices.

Comparison of Cartilage Conduction Hearing Devices Designed by Ear Impression and Computed Tomography

The ear molds and shells of hearing devices are generally designed using ear impressions. Computed tomography (CT) can provide information concerning ear structure, which can be utilized in computer-aided design to create hearing devices. This study aimed to compare the differences in hearing devices designed using either ear impressions or CT images. The ear chip of a cartilage conduction (CC) hearing device was designed based on the ear impression and CT images of patients with aural atresia. Three patients with bilateral (n = 1) or unilateral (n = 2) aural atresia participated in this study. The aided thresholds and subjective evaluations were compared. There were no serious problems with the use of either device, and no remarkable differences were observed regarding their respective audiological and subjective benefits. Regarding the subjective patient preferences, the hearing aid with the device designed via CT imaging was better in three ears of two patients, whereas the wearing comfort of the transducer was better for the device designed via the ear impression. The subjective evaluation of appearance varied among the cases. Finally, a device that was designed using CT findings was purchased for one patient. CT images can be utilized in computer-aided design to create CC hearing devices.

Binaural Hearing Using the ADHEAR Bone Conduction System in the Monaurally Occluded Ear

Introduction: The study aimed to investigate binaural cues in the rehabilitation of unilateral occluded ears with a bone conduction hearing aid. Methods: The study sample consisted of 40 adult volunteers with normal hearing. Unilateral pseudo-conductive hearing loss was induced by inserting an earplug into the external auditory canal (EAC) and silicone material in the concha for ear impression. The adaptive speech-in-noise test (Italian Matrix test) was performed in three spatial orientations to assess binaural cues (summation, squelch, and head shadow effects). All evaluations were performed in the normal condition, after EAC occlusion, and after application of an adhesive bone conduction hearing aid. Binaural contrast differences were calculated in the three conditions. Results: In the EAC occlusion condition, there was a significant increase in the signal-to-noise ratio (SNR) in both the S₀N₀ (2.4 dB) and the S₉₀N₋₉₀ (7.7 dB) settings, and a slight albeit significant increase in the S₀N₉₀ setting (1.35 dB). After fitting the BC hearing aid, there was a reduction of −1.8 dB SNR (p < 0.001) in the S₀N₀ setting and −2 dB (p = 0.003) in the S₉₀N₋₉₀ setting. There was no improvement in the SNR (p = 0.405) in evaluation of the squelch effect (S₀N₉₀). These data were corroborated by a better binaural contrast due to a reduction in the summation effect in the monaural occlusion condition and a subsequent reduction in binaural contrast after fitting the hearing aid due to an increase in the summation effect (−2.5 dB vs. 0.3 dB; p < 0.001). Conclusions: Application of a bone conduction hearing aid in unilateral pseudo-conductive hearing loss strengthens speech recognition of noise by improving the summation effect and impeding the shadow effect of the head; however, there appears to be no improvement in speech perception in noise due to spatial release from masking.

Accuracy of digital auricular impression using intraoral scanner versus conventional impression technique for ear rehabilitation: A controlled clinical trial

PurposeThis research aims to compare the accuracy of different auricular impression techniques used to produce either a mirror image of the unaffected ear or a surgical stent and template for auricular rehabilitation. The research compares two digital ear impression techniques using an Intra-Oral digital Scanner (IOS) (with /without markers) versus a traditional technique using hydrocolloid impression materials. Material and methodsEight participants were selected with intact right ears. Patients’ right ears were digitally scanned with an IOS, once with resin markers and once without markers. A conventional auricular impression was taken for each participant, which was then scanned using a desktop scanner. The digital IOS technique with markers was set as a reference model. Total 3D deviations between the study groups were calculated using Geomagic control software (software for 3D coordinate measuring technology). An independent sample t-test was used to make comparisons between the two tested groups. ResultsThe conventional impression and the intraoral scan without markers recorded a mean of 1.4057 ± 0.3581 and 0.7605±0.1469, respectively, of total 3D deviation from the intraoral scan with markers. There was a significant difference in auricular impression accuracy between conventional and intraoral scans without markers. ConclusionsUsing intraoral scanners facilitates impression acquisition and increases the accuracy compared to traditional hydrocolloid impression techniques, which may affect the shape of tissue due to its liability to be compressed by the impression material.Using markers allows for very precise data collection, reducing stitching complications that affect the accuracy of scans taken without markers. Clinical SignificanceThe proposed technique for auricular digital impression using an intraoral scanner guarantees a fast technique with accurate results in acquiring anatomical data for the rehabilitation of ear defects.This research was registered on clinicaltrials.gov with the following registration number: NCT04893902.

OD17 - Physical characterisation of commercial ear impression materials for use as a bolus in radiotherapy

OD17 - Physical characterisation of commercial ear impression materials for use as a bolus in radiotherapy

The comparison of changes in hearing thresholds and insertion losses due to occlusion induced by ear impression in sound field assessment

Background and Aim: The methods of deter­mining the amount of sound attenuation by ear mold, earplug or any other foreign body that placed in or out of the ear canal, is divided in subjective and objective. Due to the contradic­tory results in the studies in this field, this study aimed to use more audiometric frequencies con­sidering the strengths and weaknesses of previ­ous studies. Methods: This study was conducted on 30 indi­viduals with normal hearing in the age range of 21-26-year-old. First the impression mold was prepared from both ears. The evaluating real ear unaided response and the real ear occluded res­ponse. In the next step, hearing thresholds were assessed by sound field with a precision of 1 dB, once in both open ear and once in both clo­sed ears. Finally, the insertion loss due to mold placement at each frequency was compared with the amount of behavioral threshold changes at the same frequency. Results: By using paired t-test at frequencies of 400, 500, 800, 1000, 1500, 1600, 2000, 2500, 3000, 4000, 5000, 6000, 6300 and 8000 Hz, the difference in behavioral hearing thresholds with and without molding was greater than the amo­unt of the insertion loss (p &lt; 0.001). Conclusion: The insertion loss due to impre­ssion for behavioral assessment at all of the tes­ted frequencies were more than the attenuation in real ear evaluation (p &lt; 0.001). In this regard, consequently the standard deviation of insertion loss due to impression in behavioral threshold condition was more than real ear measurement. Keywords: Sound field assessment; insertion loss; real ear occluded response; ear impression; probe microphone measurement; real ear measurement

A systematic review on ear anthropometry and its industrial design applications

AbstractErgonomics is extensively studied to provide a scientific understanding of humans’ physical and cognitive use of products and workplaces. Ergonomics of the external ear is crucial for the industrial design of various ear‐related products. For this review, 50 articles regarding ear anthropometry and its applications in product design that met determined inclusion criteria were selected after searching four databases, including Scopus, Web of Science, PubMed, and Science Direct. Previous anthropometric information acquired with traditional measurement, photogrammetric method, and three dimensional (3D) anthropometric techniques (photogrammetry, magnetic resonance imaging, computerized tomography, 3D scanning, and ear impression). Those studies demonstrated that demographic factors, including age, ethnicity, gender, and ear symmetry, should be considered when designing for specific markets. Ear sizes kept growth throughout the entire lifetime. Results also showed that males had larger ear sizes than females in most populations. Most of linear, area, and ratio dimensions showed a good symmetry between left and right ears, while angular dimensions tended to be nonsymmetric. Differences in anthropometric findings existed among Asian, Western, and African populations. Hence, there is a need to establish more universal anthropometric databases for different ethnicities to meet the development of product form and function. Furthermore, fit and comfort perception was important to be examined for product design, which can be studied through questionnaire on comfort perception, analysis online comments of consumers, and virtual fit analysis. With a comprehensive presentation of literature, future research opportunities were inspired from the perspective of industrial design.

Complications Resulting from Taking Ear Impressions

In 2012, we carried out a study in a large sample to understand the secondary injuries caused during the taking ear impressions for hearing aids. This study is a follow-up of previous research conducted in 1986 (285 medical institutions) and 1999 (98 medical institutions). We posted a questionnaire survey to the otolaryngology departments of 3,257 medical institutions. The response rate to the questionnaire was 62.9% (2,050 of the 3,257 institutions), and the results indicated that 301 of the 2050 institutions (14.7%) had experience with secondary injuries, with a total of 460 cases reported. In 342 of the 460 cases (74.3%), the secondary injuries occurred at hearing-aid dealerships, followed by 67 cases (14.6%) at affiliated medical institutions, and 51 cases (11.1%) in other locations, including other medical institutions, rehabilitation counseling centers, and educational institutions. The most common type of secondary injury (298 cases, 64.8%) was caused by the presence of foreign bodies in the ear, which in turn was a result of complications occurring during the removal of residual ear impression material. Of these 298 cases, 32 required excision of the foreign bodies and surgical intervention under general anesthesia. The remaining 10 cases exhibited isolated tympanic membrane perforation without foreign body-related complications. Furthermore, 146 cases (31.7%) developed bleeding and otitis externa following removal of the ear impression, and there were reports of cases with bleeding that required long-term outpatient care and treatment. Therefore, since retention of a foreign body in the ear and tympanic membrane perforation can occur even in patients without a history of surgery or prior otologic history, adjustment of hearing aids requires prior otorhinolaryngological examination. Furthermore, because of the risk of secondary injury when taking ear impressions, this procedure must be performed with caution under the guidance of an otolaryngologist.

Under the Iron Dome

Under the Iron Dome

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METHOD AND APPARATUS FOR THE REGISTRATION OF 3D EAR IMPRESSION MODELS

A method of designing hearing aid molds is disclosed whereby two shapes corresponding to graphical images of ear impressions are registered with each other to facilitate joint processing of the hearing aid design. In a first embodiment, a first graphical representation of a first ear impression is received and a feature, such as the aperture of the ear impression, is identified on that graphical model. A first vector is generated that represents the orientation and shape of that first feature. The three-dimensional translation and rotation of that first vector are determined that are necessary to align the first vector with a second vector representing the orientation and a shape of a feature, once again such as the aperture, of a second ear impression. In another embodiment, this alignment is then refined by minimizing the sum of the distances between points on the first and second graphical representations.

보청기용 범용 이어쉘을 위한 설계 파라미터에 관한 연구

In this study, main parameters: aperture, first bend and second bend which express a structure of ear canal are extracted in order to modeling and manufacture the ready-made ear shells of hearing aids. The proposed parameter extraction method consists of 2 important algorithms, aperture detection and feature detection. In the aperture detection algorithm, aperture of 3-D scanned virtual ear impression and parameters relating to ear shell of hearing aid are determined. The feature detection algorithm detects first bend, second bend, and related parameters. Through these two algorithms, parameters for aperture, first bend, and second bend are extracted to model the ready-made ear shell of hearing aid. The values of these extracted parameters from 36 people’s right ear impression are analyzed and measured statistically. As a result of the analysis, it has been found that it is possible to classify ready-made ear shell parameters by age and size. The ready-made ear shell parameters are classified 3-size for 20 years old and 2-size for 60 years olde. Using 3D rhino program, virtual ready-made ear shell is reconstructed by parameters of every type, and simulated to model it. A final product was produced by transferring simulation result with rapid prototyping system. The modeled ready-made ear shell is evaluated with the objective and subjective method. Objective method is the comparison volume ratio and overlapped volume ratio of ear impression from randomly chosen 18 people and ready-made ear shell. And subjective method is that the final product of ready-made ear shell is used by users and the satisfaction number drawn from well fitting and comfortable testing was evaluated. In the result of the evaluation, it has been found that volume ration is 70%, big and middle size ready-made ear shell products are possible, and the satisfaction number is high.

Beyond BTEs: Earmold Opportunities in Clinical Practice

Beyond BTEs: Earmold Opportunities in Clinical Practice

The Measurement of 2D Curvature of In-Vivo Human Ear Canal

Problem To non-invasively measure the 2D curvature of human ear canal and produce the earmold by the non-invasive 3D ear impression. Methods The images of external ear were scanned by high-resolution computed tomography (HRCT). The resolution for each slice was 512⋉512 pixels. The pixel size was 0.188⋉0.188mm and the slice thickness was 0.625mm. The boundary between tympanic membrane and external auditory meatus was enhanced by image processing. Additionally, 3D model of ear canal was reconstructed by 2D images. The length and angle of first and second bends of canal were measured based on the 3D model. 2D curvature of first and second bends of canal was then computed by sine and cosine laws. Results The volume of ear canal was 862.0 cubic mm. The angle and curvature of superior wall of first bend at axial view were 121.5 degrees and 0.0685; of inferior wall of first bend were 246 degrees and −0.1102; of superior wall of second bend were 227.8 degrees and −0.0332; of inferior wall of second bend were 143.1 degrees and 0.0130 respectively. 2D curvature of superior and inferior wall of first and second bends was diagrammed. Conclusion The 2D curvature of ear canal at first and second bends could be measured and produce the ear impression non-invasively. The geometry of canal changed by tumors is a common syndrome in ear disease. Therefore, the geometry of ear canal can be tracked after the otoplasty. Significance The 3D geometry of canal can help physicians diagnose the syndrome of external canal before otoplasty. Moreover, the hearing aid earmold can be made by non-invasive ear impression instead of invasive ear impression.

Middle ear trauma resulting from hearing aid impressions

Objectives: Middle ear trauma resulting from hearing aid impressions has rarely been reported in the literature. Though this is a rare cause of middle ear injury, it can be associated with significant morbidity, particularly if it is not recognized or if not managed properly. This study describes a case of unilateral chronic otitis and hearing loss in a 73-year-old male patient who was found to have impression material in his middle ear several months after being fitted for hearing aids. In the English literature, only 4 other cases of trauma to the middle ear from ear impression material, resulting in retention of impression material in the middle ear cavity, have ever been described. This study describes a case and reviews the literature on manifestations of trauma resulting from ear impressions. Methods: This is a retrospective chart review, description, and critical evaluation of a patient who presented with hearing loss and chronic otitis, that following evaluation and surgical exploration, revealed to be due to trauma and retention of hearing aid impression material. Results: A 73-year-old male patient with chronic otitis and hearing loss from ear impression material in his middle ear was successfully diagnosed and treated. Conclusion: Hearing aid impressions are a very rare, yet important, cause of middle ear trauma. The otolaryngologist needs to be aware of the existence, diagnosis, and management of this in order to include it in the differential diagnosis of chronic otitis and hearing loss and to promptly and properly treat this problem.

If you blame buffing for bad fittings, you've probably given the wrong impression

In Brief When a hearing aid fitting is too loose and a remake is required, the authors say it's usually the ear impression that's to blame. They suggest ways to reduce the likelihood of remakes.

Advantages of a new miniature hearing aid for mild to moderate hearing loss.

To evaluate the performance of a new, miniature, behind-the-ear hearing aid designed for individuals with mild to moderate high-frequency hearing loss who need an aid but are reluctant to try one. The aid is essentially invisible, leaves the ear canal open, and can be fit in less than 30 minutes without an ear impression. The cost is less than $500. A 4-week trial of the aid in 63 ears (62 subjects) with mild to moderate bilateral hearing loss. A questionnaire was completed at the end of the study by each subject asking them to evaluate several features of the aid (cosmesis, comfort, understanding speech, amplification, and so forth) and to compare their unaided performance in quiet and in noise with the test hearing aid. A rating scale of 1 to 10 was used, with 10 being excellent and 1 poor. Subjective improvement in understanding speech in both quiet (5.8-->7.3) and noise (4.6-->5.9) occurred with the aid. Cosmesis, comfort, and appearance were highly rated (mean scores, > 8). This aid appears to have several features (comfort, cost, performance, and cosmesis) that make it ideal as a first aid for patients with mild to moderate losses.

Development of a novel audiological clinical material

Existing ear mould technology depends mainly on dental-based materials and techniques which have retarded provision of effective ear mould services world-wide. We provided a range of higher alkyl methacrylate polymeric systems suitable for use in both ear impression construction and ear mould fabrication. This novel clinical material (Otana) and the associated technique for its fabrication have several clinical and economic advantages over traditional materials currently used in audiology.

Method and apparatus for producing an ear impression

On the basis of a hollow die including over-shell and a cap drawn onto a proximal connector of the die, an ear impression is produced directly in the auditory canal that is filled with ear impression material. Displaced ear impression material thereby flows through a channel in the cap into the hollow interior of the die. A negative is produced from the ear impression together with a screwed-on fixing star, this negative containing impressions of the points of the fixing star. After injection of otoplastic material and repositioning of a fixing star with a die, over-shell and cap into the fixing depressions, a finished otoplastic shell can then be produced from the negative.