Hearing Aid Design Research Articles

Meaningful life changes following hearing aid use: a qualitative user perspective

Objective This study aimed to explore meaningful life changes due to hearing aid use in adult users. Design A cross-sectional survey design was used with open-ended questions analysed using inductive qualitative content analysis. Study Sample US-based adult hearing aid users (n = 653) from the Hearing Tracker website community and Lexie Hearing database. Results Participants had a mean age of 65.4 years (13.6 SD), including 61.2% males, 38.3% females (0.5% other). Analysis of 2122 meaning units from responses identified two broad domains: 'meaningful benefits’ (n = 1709; 80.5%) and 'remaining difficulties’ (n = 413; 19.5%). The meaningful benefits domain included five categories (27 sub-categories): (a) psychosocial benefits, (b) improvements in hearing, (c) personal benefits, (d) hearing aid features and connectivity, and (e) situational benefits. Participants reported enhanced relationships and improved occupational functioning as key benefits. The remaining difficulties domain contained four categories (25 sub-categories): (a) hearing aid limitations, (b) hearing and communication issues, (c) situational difficulties, and (d) personal issues. Notable difficulties included hearing aid design issues and challenges in noisy environments. Conclusion Hearing aid users reported diverse benefits and persistent challenges related to device use, illustrating the complexity of their lived experiences. These findings can inform empathetic, effective rehabilitation strategies and user-centric hearing aid technologies.

Classification, registration and segmentation of ear canal impressions using convolutional neural networks

Today, fitting bespoke hearing aids involves injecting silicone into patients’ ears to produce ear canal molds. These are subsequently 3D scanned to create digital ear canal impressions. However, before digital impressions can be used they require a substantial amount of effort in manual 3D editing. In this article, we present computational methods to pre-process ear canal impressions. The aim is to create automation tools to assist the hearing aid design, manufacturing and fitting processes as well as normalizing anatomical data to assist the study of the outer ear canal’s morphology. The methods include classifying the handedness of the impression into left and right ear types, orienting the geometries onto the same coordinate system sense, and removing extraneous artifacts introduced by the silicone mold. We investigate the use of convolutional neural networks for performing these semantic tasks and evaluate their accuracy using a dataset of 3000 ear canal impressions. The neural networks proved highly effective at performing these tasks with 95.8% adjusted accuracy in classification, 92.3% within 20° angular error in registration and 93.4% intersection over union in segmentation.

The influence of temporal (a)synchrony and linguistic complexity on audiovisual speech perception

Audiovisual (AV) cues often lead to improved speech understanding, especially when the auditory input is impoverished (e.g., in background noise, for people with hearing loss). This AV improvement occurs when both the auditory and visual information can be integrated together effectively (e.g., through temporal synchrony). However, whether the complexity of speech signals influences this integrated percept and how this contributes to speech understanding is still unknown. This study investigates whether individual differences in perception of temporal synchrony of the auditory and visual speech signal explain individual variability in AV speech recognition, and whether this differs across different levels of linguistic processing. By implementing five different levels of linguistic complexity (i.e., varying phoneme-viseme connections, vocabulary knowledge and/or linguistic context) and introducing temporal asynchrony in a remote task with English speaking adults we ask the following questions: (1) Is temporal synchrony needed to observe AV speech perception benefits? (2) Does this vary by linguistic level? (3) Does linguistic complexity influence synchrony perception? (4) And does synchrony perception explain individual variability in AV speech perception? These findings add value in deciding how AV synchronization should be balanced in hearing aid designs as well as in augmented / virtual reality devices.

Skin and soft tissue complications of bone-anchored hearing aids: Introducing a new classification system

ObjectivesThere have been significant surgical and technological advances in bone-anchored hearing aid (BAHA) design, function, and implantation technique, but peri-implant skin complications remain the most frequent complication. The most important aspect in dealing with cutaneous complications is to identify the type of cutaneous lesion.Although Holger's Classification has been an extremely useful clinical tool, this grading system has been shown to be unsuitable for some cases. We therefore propose a new consistent and easy assessment classification of cutaneous complications associated with BAHA. MethodsA retrospective clinical study was carried out at a tertiary centre, between January 2008 and December 2014. All patients under 18 years old with a unilateral BAHA were included in the study. ResultsA total of 53 children, with a BAHA, were included in the study. Post-operative skin complications were observed in 49.1% of the patients. Of the children, 28.3% presented with soft tissue hypertrophy, the most frequently reported skin complication, and grading according to the Holger's classification was not considered feasible.To overcome the difficulties we face in clinical practice, a new classification was developed and presented. ConclusionThe new proposed classification – Coutinho Classification – aims to fill the gaps in the one used currently by introducing new clinical features, most importantly the presence/absence of tissue overgrowth, and by providing a better description of what each category encompasses. This is an inclusive and objective new classification system, maintaining applicability, and useful in guiding the treatment.

Data-driven audiogram classifier using data normalization and multi-stage feature selection

Audiograms are used to show the hearing capability of a person at different frequencies. The filter bank in a hearing aid is designed to match the shape of patients’ audiograms. Configuring the hearing aid is done by modifying the designed filters’ gains to match the patient’s audiogram. There are few problems faced in achieving this objective successfully. There is a shortage in the number of audiologists; the filter bank hearing aid designs are complex; and, the hearing aid fitting process is tiring. In this work, a machine learning solution is introduced to classify the audiograms according to the shapes based on unsupervised spectral clustering. The features used to build the ML model are peculiar and describe the audiograms better. Different normalization methods are applied and studied statistically to improve the training data set. The proposed Machine Learning (ML) algorithm outperformed the current existing models, where, the accuracy, precision, recall, specificity, and F-score values are higher. The reason for the better performance is the use of multi-stage feature selection to describe the audiograms precisely. This work introduces a novel ML technique to classify audiograms according to the shape, which, can be integrated to the future and existing studies to change the existing practices in classifying audiograms.

Speech Separation Methodology for Hearing Aid

In the design of hearing aids (HA), the real-time speech-enhancement is done. The digital hearing aids should provide high signal-to-noise ratio, gain improvement and should eliminate feedback. In generic hearing aids the performance towards different frequencies varies and non uniform. Existing noise cancellation and speech separation methods drops the voice magnitude under the noise environment. The performance of the HA for frequency response is non uniform. Existing noise suppression methods reduce the required signal strength also. So, the performance of uniform sub band analysis is poor when hearing aid is concern. In this paper, a speech separation method using Non-negative Matrix Factorization (NMF) algorithm is proposed for wavelet decomposition. The Proposed non-uniform filter-bank was validated by parameters like band power, Signal-to-noise ratio (SNR), Mean Square Error (MSE), Signal to Noise and Distortion Ratio (SINAD), Spurious-free dynamic range (SFDR), error and time. The speech recordings before and after separation was evaluated for quality using objective speech quality measures International Telecommunication Union -Telecommunication standard ITU-T P.862.

Perceived Sound Quality of Hearing Aids With Varying Placements of Microphone and Receiver.

Perceived sound quality was variously compared between either no aiding or aiding with three models of hearing aid that varied the microphone position around the pinna, depth of the receiver in the auditory meatus, degree of meatal occlusion, and processing sophistication. The hearing aids were modern designs and commercially available at the time of testing. Binaural recordings of multichannel spatially separated speech and music excerpts were made in a manikin, either open ear or aided. Recordings were presented offline over wide-bandwidth, high-quality insert earphones. Participants listened to pairs of the recordings and made preference ratings both by clarity and externality (a proxy for "spaciousness"). Two separate groups of adults were tested, 20 with audiometrically normal hearing (NH) and 20 with mild-to-moderate sensorineural hearing loss (hearing impaired [HI]). For ratings of speech clarity, the NH group expressed no preference between the open ear and a deeply inserted occluding aid, both of which were preferred to a low-pass filtered output of the same aid. For the music signal, a small preference emerged for the open-ear recording over that of the aid. For the HI group, clarity of the deeply inserted aid was similar to in-the-ear and behind-the-ear devices for speech, but worse for music. Ratings of spaciousness produced no clear result in either group, which can be attributed to study limitations and/or participant factors. Based on clarity, a wide bandwidth, particularly to beyond 5 kHz generally and below 300 Hz for music, is desirable, independent of hearing aid design.

External ear anatomy and variations in neonates.

It is aesthetically important that the auricle has a natural and beautiful shape. The sizes, position and symmetry of normal auricle are used for different purposes in different disciplines. A deformation in the auricle of neonates and its size or location on the face may indicate a possible anomaly. The aim of this study is to investigate the normal sizes, anomaly types, anomaly rates and the relationship between hearing screening test results and auricular anomaly of the neonatal auricle. The length, width, angle, and distance measurements of the auricle were made in neonates (n=550). Anomaly types of auricle were observed. Goniometer was used to measure angles; digital caliper and ruler were used to measure lengths. Anomalies were detected by the method of observation. In the morphometric data of the neonatal auricle, differences were determined in length and width values in terms of gender. Various types of anomalies were observed in the right ear of 96 participants and in the left ear of 103 participants. Normal auricle size, position and symmetry are important for surgical reconstructions, hearing aid design, producing data banks on gender, age and ethnicity, and providing reference information for multiple diagnostic and forensic procedures. Recognition and early detection of auricular anomalies play an essential role in clinical diagnosis and their correction with special devices.

Design of Hearing Aid and Speech Device for People Hearing Dissorders

<div class="page" title="Page 1"><div class="layoutArea"><div class="column"><p><span>Deafness is a condition in which a person cannot hear due to a disturbance in his hearing organs. In communicating, most of the deaf sufferers only receive hearing aids. WHO (World Health Organization) initiated the Sound of Hearing 2030 by preventing hearing loss by 50% in 2015 and 90% in 2030. The main objective of Sound of Hearing is to develop a comprehensive, inclusive, and sustainable ear care program. Various studies on tools for deafness have been developed. However, this tool is only used to help deaf hearing but not to help speech learning (learn to speak). Thus we need hearing aids and speech learning tools for the deaf. This tool can be a government program, namely supporting a diffable-friendly Indonesia. The tool is designed like a headband, where the headband is composed of a row of vibrating modules that will be connected to the Google Assistant on a smartphone, so that any sound received by the Google Assistant will be sent to the tool to be converted into a vibration pattern. It is from these vibration patterns that a deaf person will get experience in recognizing sounds and learn to speak based on the vibration patterns that are formed. With the design of this tool, it hoped that it can help deaf people and get support from the community and government to create a diffable-friendly Indonesia. </span></p></div></div></div>

Skin and soft tissue complications of bone-anchored hearing aids: Introducing a new classification system

ObjectivesThere have been significant surgical and technological advances in bone-anchored hearing aid (BAHA) design, function, and implantation technique, but peri-implant skin complications remain the most frequent complication. The most important aspect in dealing with cutaneous complications is to identify the type of cutaneous lesion.Although Holger's Classification has been an extremely useful clinical tool, this grading system has been shown to be unsuitable for some cases. We therefore propose a new consistent and easy assessment classification of cutaneous complications associated with BAHA. MethodsA retrospective clinical study was carried out at a tertiary centre, between January 2008 and December 2014. All patients under 18 years old with a unilateral BAHA were included in the study. ResultsA total of 53 children, with a BAHA, were included in the study. Post-operative skin complications were observed in 49.1% of the patients. Of the children, 28.3% presented with soft tissue hypertrophy, the most frequently reported skin complication, and grading according to the Holger's classification was not considered feasible.To overcome the difficulties we face in clinical practice, a new classification was developed and presented. ConclusionThe new proposed classification – Coutinho Classification – aims to fill the gaps in the one used currently by introducing new clinical features, most importantly the presence/absence of tissue overgrowth, and by providing a better description of what each category encompasses. This is an inclusive and objective new classification system, maintaining applicability, and useful in guiding the treatment.

Multirate Audiometric Filter Bank for Hearing Aid Devices.

The frequency-dependent nature of hearing loss poses many challenges for hearing aid design. In order to compensate for a hearing aid user's unique hearing loss pattern, an input signal often needs to be separated into frequency bands, or channels, through a process called sub-band decomposition. In this paper, we present a real-time filter bank for hearing aids. Our filter bank features 10 channels uniformly distributed on the logarithmic scale, located at the standard audiometric frequencies used for the characterization and fitting of hearing aids. We obtained filters with very narrow passbands in the lower frequencies by employing multi-rate signal processing. Our filter bank offers a 9.1× reduction in complexity as compared to conventional signal processing. We implemented our filter bank on Open Speech Platform, an open-source hearing aid, and confirmed real-time operation.

Lightweight End-to-End Speech Enhancement Generative Adversarial Network Using Sinc Convolutions

Generative adversarial networks (GANs) have recently garnered significant attention for their use in speech enhancement tasks, in which they generally process and reconstruct speech waveforms directly. Existing GANs for speech enhancement rely solely on the convolution operation, which may not accurately characterize the local information of speech signals—particularly high-frequency components. Sinc convolution has been proposed in order to allow the GAN to learn more meaningful filters in the input layer, and has achieved remarkable success in several speech signal processing tasks. Nevertheless, Sinc convolution for speech enhancement is still an under-explored research direction. This paper proposes Sinc–SEGAN, a novel generative adversarial architecture for speech enhancement, which usefully merges two powerful paradigms: Sinc convolution and the speech enhancement GAN (SEGAN). There are two highlights of the proposed system. First, it works in an end-to-end manner, overcoming the distortion caused by imperfect phase estimation. Second, the system derives a customized filter bank, tuned for the desired application compactly and efficiently. We empirically study the influence of different configurations of Sinc convolution, including the placement of the Sinc convolution layer, length of input signals, number of Sinc filters, and kernel size of Sinc convolution. Moreover, we employ a set of data augmentation techniques in the time domain, which further improve the system performance and its generalization abilities. Compared to competitive baseline systems, Sinc–SEGAN overtakes all of them with drastically reduced system parameters, demonstrating its effectiveness for practical usage, e.g., hearing aid design and cochlear implants. Additionally, data augmentation methods further boost Sinc–SEGAN performance across classic objective evaluation criteria for speech enhancement.

The Efficacy of Digital Hearing Aids in the Management of Tinnitus in Individuals with Sensorineural Hearing Loss.

Tinnitus is a condition which is often seen coexisting with hearing loss. In many persons with tinnitus, the use of amplification devices has been reported to show improvement in difficulties due to tinnitus. Though the underlying physiological mechanism is not clearly understood, hearing aids have proven beneficial. The aim of the study is to evaluate the benefit of the hearing aid in management of tinnitus. This study was conducted to assess whether such claims are true and, if so, what is the quantum of such benefit. In order to ascertain this, we studied the effects of three commonly used newer designs of digital programmable hearing aids namely, (i) Hearing aids with Basic programming, D-Basic (ii) those with tinnitus specific programming, DTS and (iii) those with in-built masking facility, DIM. In this study 108 subjects (65 males and 43 females), in the age range of 18 to 81 years were included. Each subject was fitted with one of the above mentioned three types of hearing aids, by qualified audiologists, purely on clinical grounds. All the subjects showed improvement in their hearing. The efficacy of the hearing aids, in mitigating the tinnitus, was assessed by employing the Tinnitus Handicap Inventory - THI. The THI has been developed by Newman et al in 1996 to study the effects of tinnitus, comprehensively under three domains viz. functional, emotional and catastrophic domains. A reduction in the THI scores indicates improvement. This tool is very popular and is acclaimed worldwide. It had been translated into several languages. In this study, the translated Telugu language version (THIT) of THI was used. The use of the local language (Telugu) afforded easy comprehension and better reliability. In each subject, we documented the THIT scores, before fitting of hearing aid and after two months of proper usage of the hearing aids. In the entire sample population of 108 subjects, across all the three different designtypes of hearing aids, we found a mean reduction of 42.6 points in the THIT scores. When the design of hearing aid was taken into reckoning, the mean post-fitting reduction of THIT scores in the subjects fitted with D-Basic, DTS, DIM hearing aids were 32.2, 43.5 and 51.9 respectively. In all the three designs, several subjects, those who were in a worse grade of tinnitus severity category of tinnitus severity before fitting, improved to a better grade after fitting. Further, we studied relief in the domain sub scales of the THIT viz. functional, emotional and the catastrophic domains. While all the three designs gave over-all relief of tinnitus, we found differences in the domain sub scales. However, designs with the In built maskers and tinnitus specific programming fared better. The conclusion drawn from our study is that, apart from the amplification benefit, all the three types of digital programmable hearing aids provided appreciable mitigation of tinnitus. Among the three design-types, hearing aids with inbuilt masker (DIM) were found to give the best benefit. Hearing aids with tinnitus specific programming (DTS) were the second best.

Numerical analysis of the effects of ossicular chain malformations on bone conduction stimulation

To assess the effects of ossicular chain malformations on the performance of bone conduction hearing aids, a human ear finite-element model that includes an ear canal, a middle ear, and a spiral cochlea incorporating the third windows was established. This finite element model was built based on micro-computed tomography scanning and reverse modelling techniques, and the reliability of the finite element model was verified by comparison with reported experimental data. Based on this model, two main types of ossicular chain malformations, i.e., the incudostapedial disconnection and the ossicles fixation, were simulated, and their influences on bone conduction were analyzed by comparing the trans-cochlear-partition differential pressures. The results indicate that the incudostapedial disconnection mainly deteriorates the bone conduction response at mid frequencies. The stapes fixation has the largest effect among the ossicles fixation with the bone conduction stimulation, which also mainly decreases the mid-frequency response of the bone conduction, especially at 2 kHz. As the speech intelligibility has the most important frequency range at the range between 1 kHz and 2.5 kHz, the mid-frequency deterioration caused by ossicular chain malformations should be compensated in optimizing the design of the bone conduction hearing aids. For treating patients with the ossicular chain malformations, especially for the patients who suffer from the stapes fixation, the output of bone conduction hearing aids’ actuator in the middle frequency band should be improved.

Iterative Prototypes as ‘Boundary Objects’: Facilitating Interdisciplinary Collaboration of a Modular Hearing Aid

ABSTRACT This article investigates the use of iterative prototyping to facilitate interdisciplinary collaboration in the design and development of an innovative self-fit modular hearing aid. The design process for the hearing aid generated over 200 iterative models, each of which was additive manufactured in plastic, polymer, plaster or metal. The team developed a system for understanding the contribution of prototypes by situating these as variously propositional, material, mechanical, experiential or behavioural. Throughout the design process the hearing aid prototypes operated as boundary objects at the intersection of disciplines. They assisted the interdisciplinary team to integrate their domain-specific knowledge and collaborate across boundaries. The paper argues that boundary objects are a helpful way to collaborate in innovative projects.

Reconfigurable Filter Bank Design Techniques for Hearing Aid Performance Improvement

Hearing is one of the most crucial sense for human beings as it connects them to external world. Hearing loss impairs communication which is an essential human function. Hearing disability has massive negative impact on life, work, physical and emotional well-being as well as relationships and is rated as the third most common health problem affecting relations and quality of life. Hearing aid devices can selectively intensify sound signals in order to suit the hearing characteristics of the patients and is a boon for people with hearing misfortune. However, there is a huge gap between the potential and actual hearing aid users. This work provides a critical look into the various challenges posed by hearing aid users, the comparative of the existing state-of-art hearing devices and throws light on bottlenecks in hearing aid design and performance. Filter bank, being the holy grail of Digital Hearing aid, needs special attention for improving the hearing aid performance. Reconfigurability is the need of the hour for providing flexible and tailormade hearing aids that can suit individual hearing requirements. The paper discusses and gives an in-depth insight into the techniques for reconfigurable Filter bank design for performance augmentationin terms of parameters like Signal quality, Auditory compensation, Computational and Hardware complexity, area, speed, power, etc.

Acoustic feedback path modeling for hearing aids: Comparison of physical position based and position independent models.

Acoustic feedback in hearing aids occurs due to the coupling between the hearing aid loudspeaker and microphones. In order to reduce acoustic feedback, adaptive filters are often used to estimate the feedback path. To increase the convergence speed and decrease the computational complexity of the adaptive algorithms, it has been proposed to split the acoustic feedback path into a time-invariant fixed part and a time-varying variable part. A key question of this approach is how to determine the fixed part. In this paper, two approaches are investigated: (1) a digital filter design approach that makes use of the signals of at least two hearing aid microphones and (2) a defined physical location approach using an electro-acoustic model and the signals of one hearing aid microphone and an additional ear canal microphone. An experimental comparison using measured acoustic feedback paths showed that both approaches enable one to reduce the number of variable part coefficients. It is shown that individualization of the fixed part increases the performance. Furthermore, the two approaches offer solutions for different requirements on the effort to a specific hearing aid design on the one hand and the effort during the hearing aid fitting on the other hand.

Sentence perception in noise by hearing-aid users predicted by syllable-constituent perception and the use of context.

Masked sentence perception by hearing-aid users is strongly correlated with three variables: (1) the ability to hear phonetic details as estimated by the identification of syllable constituents in quiet or in noise; (2) the ability to use situational context that is extrinsic to the speech signal; and (3) the ability to use inherent context provided by the speech signal itself. This approach is called "the syllable-constituent, contextual theory of speech perception" and is supported by the performance of 57 hearing-aid users in the identification of 109 syllable constituents presented in a background of 12-talker babble and the identification of words in naturally spoken sentences presented in the same babble. A simple mathematical model, inspired in large part by Boothroyd and Nittrouer [(1988). J. Acoust. Soc. Am. 84, 101-114] and Fletcher [Allen (1996) J. Acoust. Soc. Am. 99, 1825-1834], predicts sentence perception from listeners' abilities to recognize isolated syllable constituents and to benefit from context. When the identification accuracy of syllable constituents is greater than about 55%, individual differences in context utilization play a minor role in determining the sentence scores. As syllable-constituent scores fall below 55%, individual differences in context utilization play an increasingly greater role in determining sentence scores. Implications for hearing-aid design goals and fitting procedures are discussed.

Probabilistic model of speech with high spectral resolution using maximum-likelihood estimation

A probabilistic model for the distribution of narrowband short-time Fourier transform (STFT) coefficients, having frequency resolution of 5 Hz and below, is proposed for speech signals. An important application is to model speech to depict the perceptual stability of human listening capability which allows humans to perceive speech reliably under a wide range of acoustic conditions. Representation of speech with high spectral resolution finds applications in the design of digital hearing aids and cochlear implants for people with hearing disability. While speech is generally considered as a non-stationary signal over segment lengths longer than 20–30 ms, the perceptual stability of human auditory system motivates the need for an invariant representation of speech over long segment lengths. Computer modelling shows that STFT coefficients of speech with high-frequency resolution fit reasonably accurately to Laplace distribution (LD). Parameters of the corresponding LD are estimated using maximum-likelihood estimation. Cramer–Rao bound for the estimated parameters and root mean square error for the fitted distribution confirm the validity of the fitted distribution.

Congruent audiovisual speech enhances auditory attention decoding with EEG

Objective. The auditory attention decoding (AAD) approach can be used to determine the identity of the attended speaker during an auditory selective attention task, by analyzing measurements of electroencephalography (EEG) data. The AAD approach has the potential to guide the design of speech enhancement algorithms in hearing aids, i.e. to identify the speech stream of listener’s interest so that hearing aids algorithms can amplify the target speech and attenuate other distracting sounds. This would consequently result in improved speech understanding and communication and reduced cognitive load, etc. The present work aimed to investigate whether additional visual input (i.e. lipreading) would enhance the AAD performance for normal-hearing listeners. Approach. In a two-talker scenario, where auditory stimuli of audiobooks narrated by two speakers were presented, multi-channel EEG signals were recorded while participants were selectively attending to one speaker and ignoring the other one. Speakers’ mouth movements were recorded during narrating for providing visual stimuli. Stimulus conditions included audio-only, visual input congruent with either (i.e. attended or unattended) speaker, and visual input incongruent with either speaker. The AAD approach was performed separately for each condition to evaluate the effect of additional visual input on AAD. Main results. Relative to the audio-only condition, the AAD performance was found improved by visual input only when it was congruent with the attended speech stream, and the improvement was about 14 percentage points on decoding accuracy. Cortical envelope tracking activities in both auditory and visual cortex were demonstrated stronger for the congruent audiovisual speech condition than other conditions. In addition, a higher AAD robustness was revealed for the congruent audiovisual condition, with reduced channel number and trial duration achieving higher accuracy than the audio-only condition. Significance. The present work complements previous studies and further manifests the feasibility of the AAD-guided design of hearing aids in daily face-to-face conversations. The present work also has a directive significance for designing a low-density EEG setup for the AAD approach.