Middle Ear Hearing Aid Research Articles

Design and Development of a Tri-Coil Bellows Transducer for RW-Drive Implantable Middle-Ear Hearing Aid Using FEA

We describe the design and development of a tri-coil bellows transducer (TCBT) for use in an implantable middle-ear hearing aid for round window (RW) drive. The TCBT provides easy implantation and a better frequency response than previous RW middle-ear transducers. It consisted of three cylindrical coils, a bonded magnet, and a tiny bellows with multiple corrugations. The simulation started with the calculation of the vibrational force required for the RW-drive transducer. Based on the anatomical structure of the RW niche and its volume, the designed TCBT was 1.75 mm in diameter and 2.3 mm long. To maximize the electromagnetic force of a TCBT installed within the limited volume of the RW niche, its structure was designed using an electromagnetic analysis based on finite-element analysis to determine the each length of the three cylindrical coils and the bonded magnet inside the TCBT. Additionally, the resonance frequency characteristics of the TCBT were determined using mechanical vibration analysis. A prototype TCBT was fabricated according to the simulation results, and an experiment to evaluate its vibrational characteristics was performed with the TCBT in an unloaded condition. Finally, the performance of the TCBT for use in RW-drive implantable middle-ear hearing aids was confirmed in experiments with cadaveric temporal bones.

Piezoelectric Actuator with Frequency Characteristics for a Middle-Ear Implant.

The design and implementation of a novel piezoelectric-based actuator for an implantable middle-ear hearing aid is described in this paper. The proposed actuator has excellent low-frequency output characteristics, and can generate high output in a specific frequency band by adjusting the mechanical resonance. The actuator consists of a piezoelectric element, a miniature bellows, a cantilever membrane, a metal ring support, a ceramic tip, and titanium housing. The optimal structure of the cantilever-membrane design, which determines the frequency characteristics of the piezoelectric actuator, was derived through finite element analysis. Based on the results, the piezoelectric actuator was implemented, and its performance was verified through a cadaveric experiment. It was confirmed that the proposed actuator provides better performance than currently used actuators, in terms of frequency characteristics.

In-vitro and in-vivo measurement of the animal's middle ear acoustical response by partially implantable fiber-optic sensing system

The main obstacle in realization of a totally implantable hearing aid is a lack of reliable implantable microphone. In this paper we have described a potentially miniature fiber-optic vibrometer based on a modified Michelson interferometer, designed to serve as a middle-ear microphone for totally implantable cochlear- or middle-ear hearing aids. A model of the sensing system was used for in-vitro and in-vivo investigation of acoustical response of sheep's middle-ear ossicles. Surgical and implantation procedure of introducing the sensing optical fiber into the middle-ear and its aiming at the incus was investigated and described here in detail. The frequency responses of the incus was measured while a cadaver and living sheep was exposed to the sinusoidal acoustical excitation of 40–90dB SPL, in the frequency range from 100Hz to 10kHz. The amplitude of the incus vibration was found to be in the range between 10pm to 100nm, strongly depending on the frequency, with a lot of resonant peaks, corresponding mainly to the natural outer ear canal gain. The noise floor in the experiments was about 2pm/Hz1/2, but recently we have decreased it to < 0.5pm/Hz1/2, which corresponds to a minimal detectable sound level of 31–35dB(A) SPL for humans. The histological examination of temporal bones of cadaver animals and the intensity of in-vivo optical signal demonstrated that the aiming of the sensing fiber to the target has been preserved for five months after the implantation.

Study of External Ear and Middle Ear Functions and Hearing Aid Adjustments to Deal with Pathological Changes

Study of External Ear and Middle Ear Functions and Hearing Aid Adjustments to Deal with Pathological Changes

Safety and effectiveness of the Vibrant Soundbridge in treating conductive and mixed hearing loss: A systematic review.

For many years, the therapeutic approach for conductive and/or mixed hearing loss has consisted of middle ear surgery with replacement of defect ossicles, and if possible the application of a hearing aid. Advances in technology have led to the introduction of electronmagnetic active implantable devices such as the Vibrant Soundbridge (VSB). With its various coupling techniques for different pathophysiological situations in the middle ear, the VSB offers greater improvement in the hearing performance of affected persons. PubMed, OvidSP (MEDLINE), EMBASE (DIMDI), the National Institue for Health research (NIHR) Centre for Reviews and Dissemination (including the National Health Service Economic Evaluation Database, Database of Abstracts of Reviews of Effects, and Health Technology Assessment), and the Cochrane Library were searched to identify articles published between January 2006 and April 2014 that evaluated the safety and effectiveness of the VSB in comparison to no intervention, bone conduction hearing implants (BCHI), and middle ear surgery plus hearing aids for adults and children with conductive or mixed hearing loss. Study selection and data extraction was carried out by multiple reviewers. Study quality was assessed using the Oxford Centre for Evidence-Based Medicine levels of evidence (2011); and a checklist available from the Evidence Analysis Library, Academy of Nutrition and Diabetics. Thirty-six publications were identified: 19 on VSB outcomes in 294 individuals, 13 on BCHI outcomes in 666 individuals, and four on middle ear surgery plus hearing aid outcomes in 43 individuals. Two systematic reviews were also identified. Heterogeneous outcome measures made it difficult to summarize data. In general, the VSB proved to be safe and effective when compared to no intervention and BCHI, and provided more and consistent hearing gain compared to middle ear surgery plus conventional hearing aids. As demonstrated in the literature, the VSB as an active device offers an effective alternative for patients with various middle ear pathologies, particularly with mixed hearing loss and failed previous tympanoplasties when classical ossiculoplasty could not provide enough functional gain. This new strategy in hearing rehabilitation has led to an improved quality of hearing and life. Laryngoscope, 126:1451-1457, 2016.

PO-0915 Therapeutic Options For Conductive Hearing Loss In Children With Cleft Palate

Background and aim Cleft lip and palate is a common congenital malformation correlated with otological disorders like Eustachian tube dysfunction, otitis media with effusion and conductive hearing loss correlated with speech disorders. Methods In our study we evaluate the therapeutic options for the conductive hearing loss in these children, such as: middle ear ventilation tube insertion, hearing aids and adenoidectomy. We conducted a retrospective chart review on 19 patients who underwent last follow-up during 2013, aged between 1 and 16, affected by cleft palate. We identified 3 cases of Treacher-Collins syndrome, 2 cases of CHARGE syndrome, 2 case sof Pierre Robin, 1 case of Goldhenar and 1 case of Di George syndrome. In 9 cases the cleft palate was isolated. In 14 cases we conducted phoniatric and logopaedic evaluations and 10 of these showed a speech disorder. Results We found a conductive hearing loss in 12 of the 19 children.2 of these patients used hearing aids with an improvementof speech performance; 1 patient underwent adenoidectomy for the appearance of sleep apnea but he modified his quality of voice with hypernasality and nasal emission after surgery; finally 9 children had spontaneous resolution of otitis media with effusion. Conclusions In conclusion we found that the more effective way to resolve the problem of conductive hearing loss and the resulting speech disorder is to use the hearing aids until the resolution of the hearing loss, which normally occurs around 7 years old.

Electromagnetic actuator for round window vibration to compensate for vibrant characteristics of ossicular chain

Round window (RW) vibration is a new technology to help people with hearing loss. Many RW approaches have been reported because the technology provides benefits. The main reason is that the new method can be implanted in patients who cannot use general middle ear hearing aids. Such patients, who lack a part of the ossicles, cannot preserve normal auditory response because the auditory path of RW vibration does not include the middle ear. Therefore, an electromagnetic RW actuator is implemented that compensates for the loss of middle ear's property. It has a vibrant frequency corresponding to normal characteristics of the human middle ear. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Implementation of a direct install 3-pole type EM transducer in round window niche for implantable middle ear hearing aids

Since the 1980's, various types of implantable hearing aids using unique means for delivering acoustic power to the inner ear have been developed. Recently, implantable hearing aids that stimulate the round window by the middle ear transducer have received great attention because it reduces loading effect at the ossicular chain. In this study, we have implemented a direct install 3-pole type EM transducer in round window niche for implantable middle ear hearing aid. The 3-pole type EM transducer consists of two permanent magnets and three coils and exhibit structural features that minimize leakage flux, thereby permitting high efficiency and low magnetic field interference. The stapes velocity was measured using a laser Doppler vibrometer in response to the round window stimulation from the transducer. To verify the usefulness of the 3-pole type EM transducer, we compared the stapes vibration characteristics produced by the transducer and those from a sound source. The magnitude of stapes velocity due to the round window stimulation at 1 mArms was equivalent to that of stapes velocity at 94 dB SPL sound stimulation. Thus, the evaluation study shows that the 3-pole type EM transducer is suitable for implantable hearing devices.

정원창 구동기의 진동체 성능 평가를 위한 내이 물리모델

Recently, various hearing aids are developed to overcome hearing loss. There are available hearing aids, such as air conduction hearing aid, implantable middle ear hearing aid and so on. But air conduction hearing aid is inconvenience caused by howling, and ossicle chain driving type implantable middle ear hearing aid has some week point due to problem of possible nercobiosis of coupling spot along incus long process. In recent years, in order to improve these shortcomings round window (RW) driving hearing aid has been paying attention. In this paper, the physical cochlear model is proposed for a performance evaluation of the RW driving hearing aids of a transducer. In order to verify an experiment proposed on a performance of physical cochlear model, the transducer which has ossicles characteristics is used. By measuring and comparing the frequency characteristics of transducer with ossicles and human temporal bone, performance of physical cochlear model was verified. As from the result of experiment, it is expected that an implemented cochlear model is useful for evaluating characteristics of RW transducer.

MEMS Capacitive Accelerometer-Based Middle Ear Microphone

The design, implementation, and characterization of a microelectromechanical systems (MEMS) capacitive accelerometer-based middle ear microphone are presented in this paper. The microphone is intended for middle ear hearing aids as well as future fully implantable cochlear prosthesis. Human temporal bones acoustic response characterization results are used to derive the accelerometer design requirements. The prototype accelerometer is fabricated in a commercial silicon-on-insulator (SOI) MEMS process. The sensor occupies a sensing area of 1mm × 1mm with a chip area of 2mm × 2.4mm and is interfaced with a custom-designed low-noise electronic IC chip over a flexible substrate. The packaged sensor unit occupies an area of 2.5mm × 6.2mm with a weight of 25mg. The sensor unit attached to umbo can detect a sound pressure level (SPL) of 60dB at 500Hz, 35dB at 2kHz, and 57dB at 8kHz. An improved sound detection limit of 34-dB SPL at 150Hz and 24-dB SPL at 500Hz can be expected by employing start-of-the-art MEMS fabrication technology, which results in an articulation index of approximately 0.76. Further micro/nanofabrication technology advancement is needed to enhance the microphone sensitivity for improved understanding of normal conversational speech.

Assessment and Management of Hearing Loss in Children with Cleft Lip and/or Palate: a Review

Hearing loss as a common comorbidity in children with cleft lip and/or palate has been well documented. Auditory impairment may contribute to abnormalities in speech, language and learning abilities, and other communicative disorders in children with oral clefs. The functional consequences of hearing loss in this group should not be underestimated. In this paper, the existing literature is reviewed with an emphasis on the prevalence, type, assessment, and management methods for hearing loss in children with clef lip and/or palate. The prevalence of hearing disorders reported in western patients with clef lip and/or palate is generally higher than in the eastern countries. However, hearing loss is common in children with clef lip and/or palate of all ethnicities. Conductive hearing loss caused by middle ear disease is reported to occur frequently in syndromic and non-syndromic clef cases. The prevalence of sensorineural hearing loss is relatively higher in syndromic clefs than nonsyndromic clefs. Assessments of hearing loss in children with clefs should include case history taking and a detailed audiometric evaluation, and should be performed by otolaryngology and audiology professionals. Surgical treatment, including closure of clefs and ventilation tube insertion, is reported to be effective in reducing conductive hearing loss but this remains controversial. Nonsurgical treatments for middle ear disease and hearing aids have also been suggested in recent studies. This review also highlights the possible role of central auditory processing disorder in the hearing loss of children with clef lip and/or palate, and recommends the systematic study of central auditory processing in children with clef lip and/or palate.

A Case Study of an 11-Year-Old With Auditory Processing Disorder

The article presents a case study of a child ('Sally') with multiple risk factors for auditory processing disorder (APD), including low birth weight and a history of otitis media. Sally presented for auditory processing assessment at age 7 years 9 months due to learning difficulties, despite normal intelligence. Sally had persistent mild hearing loss associated with repeated middle ear infections and hearing aids were trailed at 22 months. Mother reported increased vocalisations and improved listening with hearing aids. Three years later, hearing aids were withdrawn, as Sally's hearing thresholds had improved. Following diagnosis of APD an FM device was trailed successfully, but Sally is no longer using the device. Trial of more discrete FM devices is recommended. Despite using hearing aids as a preschooler and using an FM device for a year, Sally has continued to have auditory difficulties. An inter-disciplinary approach involving the family and other professionals such as teachers, educational psychologists, speech pathologists, and audiologists, might have ensured better outcomes for Sally.

Quasi-static transfer function of the rabbit middle ear' measured with a heterodyne interferometer with high-resolution position decoder.

Due to changes in ambient pressure and to the gas-exchange processes in the middle ear (ME) cavity, the ear is subject to ultra-low-frequency pressure variations, which are many orders of magnitude larger than the loudest acoustic pressures. Little quantitative data exist on how ME mechanics deals with these large quasi-static pressure changes and because of this lack of data, only few efforts could be made to incorporate quasi-static behavior into computer models. When designing and modeling ossicle prostheses and implantable ME hearing aids, the effects of large ossicle movements caused by quasi-static pressures should be taken into account. We investigated the response of the ME to slowly varying pressures by measuring the displacement of the umbo and the stapes in rabbit with a heterodyne interferometer with position decoder. Displacement versus pressure curves were obtained at linear pressure change rates between 200 Pa/s and 1.5 kPa/s, with amplitude +/-2.5 kPa. The change in stapes position associated with a pressure change is independent of pressure change rate (34 microm peak-to-peak at +/-2.5 kPa). The stapes displacement versus pressure curves are highly nonlinear and level off for pressures beyond +/-1 kPa. Stapes motion shows no measurable hysteresis at 1.5 kPa/s, which demonstrates that the annular ligament has little viscoelasticity. Hysteresis increases strongly at the lowest pressure change rates. The stapes moves in phase with the umbo and with pressure, but the sense of rotation of the hysteresis loop of stapes is phase inversed. Stapes motion is not a simple lever ratio mimic of umbo motion, but is the consequence of complex changes in ossicle joints and ossicle position. The change in umbo position produced by a +/-2.5 kPa pressure change decreases with increasing rate from 165 microm at 200 Pa/s to 118 microm at 1.5 kPa/s. Umbo motion already shows significant hysteresis at 1.5 kPa/s, but hysteresis increases further as pressure change rate decreases. We conclude that in the quasi-static regime, ossicle movement is not only governed by viscoelasticity, but that other effects become dominant as pressure change rate decreases below 1 kPa/s. The increasing hysteresis can be caused by increasing friction as speed of movement decreases, and incorporating speed-dependent friction coefficients will be essential to generate realistic models of ossicle movements at slow pressure change rates.

Anatomical study of the human middle ear for the design of implantable hearing aids

Objective To generate anatomical data on the human middle ear and adjacent structures to serve as a base for the development and optimization of new implantable hearing aid transducers. Implantable middle ear hearing aid transducers, i.e. the equivalent to the loudspeaker in conventional hearing aids, should ideally fit into the majority of adult middle ears and should utilize the limited space optimally to achieve sufficiently high maximal output levels. For several designs, more anatomical data are needed. Methods Twenty temporal bones of 10 formalin-fixed adult human heads were scanned by a computed tomography system (CT) using a slide thickness of 0.63 mm. Twelve landmarks were defined and 24 different distances were calculated for each temporal bone. Results A statistical description of 24 distances in the adult human middle ear which may limit or influence the design of middle ear transducers is presented. Significant inter-individual differences but no significant differences for gender, side, age or degree of pneumatization of the mastoid were found. Distances, which were not analyzed for the first time in this study, were found to be in good agreement with the results of earlier studies. Conclusion A data set describing the adult human middle ear anatomy quantitatively from the point of view of designers of new implantable hearing aid transducers has been generated. In principle, the method employed in this study using standard CT scans could also be used preoperatively to rule out exclusion criteria.

Design and analysis of a microelectromagnetic vibration transducer used as an implantable middle ear hearing aid

In this paper, we present the design and analysis of a microelectromagnetic vibration transducer for an implantable middle ear hearing aid, characterized by small size, high efficiency and selective frequency bandwidth. The electromagnetic vibration transducer is used to convert electrical energy, which is obtained from sound signals generated externally, into mechanical vibration energy, which is a means of amplifying acoustic sound for patients with sensory neural hearing loss. The electromagnetic vibration transducer can be partially implanted at a sound bridge of bone which is composed of the ossicular chain that couples the eardrum to the cochlea. For use as an implantable middle ear hearing aid, this vibration transducer must consider design parameters, such as transducer size, vibration force and frequency. The vibration transducer should have the critical size to be partially implanted at the ossicular chain in the middle ear space. The maximum vibration force of the transducer requires more than 9.6 dyne, which is according to 100 dB SPL to be compensated sound pressure level. The vibration frequency of the transducer is in the speech signal frequency range of about 100 Hz to 5 kHz. To do this, we present a new type of electromagnetic vibration transducer that is composed of a wound coil, permanent magnet and a four-beam cross silicon elastic body. In this paper we show the techniques for optimizing the electromagnetic driving part and the four-beam silicon elastic body to obtain large vibration force output and selective frequency bandwidth by using theoretical analysis and finite element analysis simulation.

Microvibration transducer using silicon elastic body for an implantable middle ear hearing aid

In this paper, the microelectromagnetic vibration transducer is presented for the use of an implantable middle ear hearing aid, characterized by its small size, high efficiency and selective frequency bandwidth. In order to construct this, a new type of electromagnetic vibration transducer, composed of wound coil, a permanent magnet and a four-beam cross type silicon elastic body, is required. The fabricated transducer is useful for the application of 1–5 mA of a current source, 0.5–55 dyn of a vibration peak force and at a frequency range of a 100–7000 Hz.

Electromagnetic vibration transducer using polyimide elastic body for implantable middle ear hearing aid

For use as an implantable middle ear hearing aid, vibration transducer should have small size, high-energy efficiency and suitable frequency bandwidth. In order to optimize the electromagnetic force for greatest efficiency, finite element analysis (FEA) simulation was preformed. Additionally, for the investigation of frequency characteristics of vibration transducer, four FEA models of polyimide elastic body were presented and simulation was performed. The electromagnetic vibration transducer characterized with high efficiency and suitable frequency bandwidth was fabricated with a polyimide elastic body for use as an implantable middle ear hearing aid. The fabricated transducer shows that displacement of vibration is 300 nm in a range from 0.1 to 1 kHz and is reduced when it is higher than 1 kHz.

Implantable middle ear hearing aid system and acoustic coupler therefor

The acoustical coupler has a closed-bottom containment with compliant diaphragm attached to the containment periphery to form an acoustic chamber. A length of tubing is connected through the side or bottom of the containment to the chamber for conveying sound pressure between the chamber and an electroacoustic transducer connected at the other end of the tubing. The transducer may be either a microphone or a hearing aid receiver. The electroacoustic transducer, being too large for direct placement within the middle ear cavity may be located elsewhere in the skull, such as behind the ear adjacent to the surface of the skin. When connected to a microphone the coupler may be placed within the middle ear cavity behind the tympanic membrane and may be attached to the malleus with a wire hook secured to the coupler diaphragm. When attached to a receiver or vibration sending unit the coupler may be attached to the incus end of the stapes using a porous disc secured to the coupler diaphragm, the porosity of the disc permitting tissue growth and infusion whereby the stapes becomes permanently attached to the disc. The acoustic couplers may be used with a wide range of electronic signal processing and amplification circuitry tailored to the particular patient's hearing loss.