Progression of Hearing Loss in the Aging Population: Repeated Auditory Measurements in the Rotterdam Study

Neural attentional filters and behavioural outcome follow independent individual trajectories over the adult lifespan

Preserved communication abilities promote healthy ageing. To this end, the age-typical loss of sensory acuity might in part be compensated for by an individual's preserved attentional neural filtering. Is such a compensatory brain-behaviour link longitudinally stable? Can it predict individual change in listening behaviour? We here show that individual listening behaviour and neural filtering ability follow largely independent developmental trajectories modelling electroencephalographic and behavioural data of N = 105 ageing individuals (39-82 y). First, despite the expected decline in hearing-threshold-derived sensory acuity, listening-task performance proved stable over 2 y. Second, neural filtering and behaviour were correlated only within each separate measurement timepoint (T1, T2). Longitudinally, however, our results raise caution on attention-guided neural filtering metrics as predictors of individual trajectories in listening behaviour: neither neural filtering at T1 nor its 2-year change could predict individual 2-year behavioural change, under a combination of modelling strategies.

Interaural and sex differences in the natural evolution of hearing levels in pre-symptomatic and symptomatic carriers of the p.Pro51Ser variant in the COCH gene

Hearing impairment constitutes a significant health problem in developed countries. If hearing loss is slowly progressive, the first signs may not be noticed in time, or remain untreated until the moment the auditory dysfunction becomes more apparent. The present study will focus on DFNA9, an autosomal dominant disorder caused by pathogenic variants in the COCH gene. Although several cross-sectional studies on this topic have been conducted, a crucial need for longitudinal research has been reported by many authors. Longitudinal trajectories of individual hearing thresholds were established as function of age and superimposed lowess curves were generated for 101 female and male carriers of the p.Pro51Ser variant. The average number of times patients have been tested was 2.49 years with a minimum of 1 year and a maximum of 4 years. In addition, interaural and sex differences were studied, as they could modify the natural evolution of the hearing function. The current study demonstrates that, both in female carriers and male carriers, the first signs of hearing decline, i.e. hearing thresholds of 20 dB HL, become apparent as early as the 3rd decade in the highest frequencies. In addition, a rapid progression of SNHL occurs between 40 and 50 years of age. Differences between male and female carriers in the progression of hearing loss are most obvious between the age of 50 and 65 years. Furthermore, interaural discrepancies also manifest from the age of 50 years onwards. High-quality prospective data on the long-term natural evolution of hearing levels offer the opportunity to identify different disease stages in each cochlea and different types of evolution. This will provide more insights in the window of opportunity for future therapeutic intervention trials.

Associations of sleep characteristics in late midlife with late-life hearing loss in the Atherosclerosis Risk in Communities-Sleep Heart Health Study (ARIC-SHHS)

OBJECTIVES

This study investigated associations of late midlife sleep characteristics with late-life hearing, which adds to the existing cross-sectional evidence and is novel in examining polysomnographic sleep measures and central auditory processing.

METHODS

A subset of Atherosclerosis Risk in Communities Study participants underwent sleep assessment in the Sleep Heart Health Study in 1996-1998 and hearing assessment in 2016-2017. Peripheral hearing thresholds (0.5-4kHz) assessed by pure-tone audiometry were averaged to calculate speech-frequency pure-tone average in better-hearing ear (higher pure-tone average=worse hearing). Central auditory processing was measured by the Quick Speech-in-Noise Test (lower score=worse performance). Sleep was measured using polysomnography (time spent in stage 1, stage 2, stage 3/4, rapid eye movement sleep; sleep-disordered breathing [apnea-hypopnea index ≥5]) and self-report (habitual sleep duration; excessive daytime sleepiness [Epworth Sleepiness Scale 10]). Linear regression models adjusted for demographic and lifestyle factors with additional adjustment for cardiovascular factors.

RESULTS

Among 719 Atherosclerosis Risk in Communities-Sleep Heart Health Study participants (61 ± 5years, 54% female, 100% White), worse speech-frequency pure-tone average was found with sleep-disordered breathing (2.51dB, 95% confidence interval: 0.27, 4.75) and excessive daytime sleepiness (3.35 dB, 95% confidence interval: 0.81, 5.90). Every additional hour of sleep when sleeping >8 hours was associated with worse Quick Speech-in-Noise score (1.61 points, 95% confidence interval: 0.03, 3.19). Every 10-minute increase in rapid eye movement sleep was associated with 0.14-point better Quick Speech-in-Noise score (95% confidence interval: 0.02, 0.25).

CONCLUSIONS

Sleep abnormalities might be risk factors for late-life hearing loss. Future longitudinal studies are needed to confirm these novel findings and clarify the mechanisms.

Managing cisplatin-ineligible patients with resected, high-risk, locally advanced squamous cell carcinoma of the head and neck: Is there a standard of care?

For the past 2 decades, cisplatin-based adjuvant chemoradiotherapy (CRT) has remained the standard of care for patients with resected, locally advanced squamous cell carcinoma of the head and neck (LA SCCHN) who are at high risk of disease recurrence. However, many patients are deemed ineligible for cisplatin-based CRT because of poor performance status, advanced biological age, poor renal function, or hearing loss. Because outcomes with radiotherapy (RT) alone remain poor, patients at high risk of disease recurrence deemed ineligible to receive cisplatin are a population with a significant unmet medical need, and alternative systemic therapy options in combination with RT are urgently needed. Clinical guidelines and consensus documents have provided definitions for cisplatin ineligibility; however, areas of debate include thresholds for age and renal impairment and criteria for hearing loss. Furthermore, the proportion of patients with resected LA SCCHN who are cisplatin ineligible remains unclear. Because of a scarcity of clinical studies, treatment selection for patients with resected, high-risk LA SCCHN who are deemed ineligible to receive cisplatin is often based on clinical judgment, with few treatment options specified in international guidelines. In this review, we discuss considerations related to cisplatin ineligibility in patients with LA SCCHN, summarize the limited clinical evidence for adjuvant treatment of patients with resected high-risk disease, and highlight ongoing clinical trials that have the potential to provide new treatment options in this setting.

Centering on People: How Hearing Care Professionals Can Adapt to Consumers' Need and Outcomes

Audiology is experiencing exponential growth in technology, service, and provision options. These advancements give hearing care professionals the opportunity to revise, potentially improve, and adapt to the modern hearing care landscape to better serve the modern consumer. Consumer needs guide care planning and delivery, with the goal of achieving outcomes that are important to both the consumer and the clinician. The changes available to the hearing care industry can also enable consumers' needs to be identified and served in a more holistic and personalized manner than has previously been possible. The purpose of this article is to explain and encourage hearing care professionals to adopt a mindset of doing whatever is reasonable and clinically appropriate to meet the need and desires of the consumer by implementing choice in service, technology, and channel across whichever model of care adopted by a provider.

Bats experience age-related hearing loss (presbycusis)

Hearing loss is a hallmark of aging, typically initially affecting the higher frequencies. In echolocating bats, the ability to discern high frequencies is essential. However, nothing is known about age-related hearing loss in bats, and they are often assumed to be immune to it. We tested the hearing of 47 wild Egyptian fruit bats by recording their auditory brainstem response and cochlear microphonics, and we also assessed the cochlear histology in four of these bats. We used the bats' DNA methylation profile to evaluate their age and found that bats exhibit age-related hearing loss, with more prominent deterioration at the higher frequencies. The rate of the deterioration was ∼1 dB per year, comparable to the hearing loss observed in humans. Assessing the noise in the fruit bat roost revealed that these bats are exposed to continuous immense noise-mostly of social vocalizations-supporting the assumption that bats might be partially resistant to loud noise. Thus, in contrast to previous assumptions, our results suggest that bats constitute a model animal for the study of age-related hearing loss.

The longitudinal relationship between hearing loss and cognitive decline in tonal language-speaking older adults in China

Introduction

Previous longitudinal studies indicate that hearing loss and cognitive impairment are associated in non-tonal language-speaking older adults. This study aimed to investigate whether there is a longitudinal association between hearing loss and cognitive decline in older adults who speak a tonal language.

Methods

Chinese-speaking older adults aged 60 years and above were recruited for baseline and 12 month follow-up measurements. All participants completed a pure tone audiometric hearing test, Hearing Impaired-Montreal Cognitive Assessment Test (HI-MoCA), and a Computerized Neuropsychological Test Battery (CANTAB). The De Jong Gierveld Loneliness Scale was used to measure loneliness, and the 21-item Depression Anxiety Stress Scale (DASS-21) was used to measure aspects of mental health. Associations between baseline hearing loss and various cognitive, mental and psychosocial measures were evaluated using logistic regression.

Results

A total of 71 (29.6%) of the participants had normal hearing, 70 (29.2%) had mild hearing loss, and 99 (41.2%) had moderate or severe hearing loss at baseline, based on mean hearing thresholds in the better ear. After adjusting for demographic and other factors, baseline moderate/severe audiometric hearing loss was associated with an increased risk of cognitive impairment at follow-up (OR: 2.20, 95% CI: 1.06, 4.50). When pure-tone average (PTA) was modeled continuously, an average difference of 0.24 in HI-MoCA scores for every 10 dB increase in BE4FA existed, and an average difference of 0.07 in the change of HI-MoCA scores in a 12 month period.

Discussion

The results revealed a significant longitudinal relationship between age-related hearing loss and cognitive decline in this cohort of tonal language-speaking older adults. Steps should also be taken to incorporate hearing assessment and cognitive screening in clinical protocols for older adults 60 years and above in both hearing and memory clinics.

Association of Carotid Atherosclerosis With Hearing Loss: A Cross-sectional Analysis of the Atherosclerosis Risk in Communities Study

Objective

To describe the association between midlife carotid atherosclerosis and late-life hearing loss among participants in the Atherosclerosis Risk in Communities (ARIC) study.

Design, Setting, and Participants

For this cross-sectional study and temporal analysis of a cohort within the ongoing ARIC prospective cohort study, participants were recruited from 4 communities in the US. The analysis evaluated information on mean carotid intima-media thickness (cIMT), from visit 1 (1987-1989) to visit 4 (1994-1996), carotid plaque presence at visit 4, and audiometric data from visit 6 (2016-2017). The cIMT measures were calculated from ultrasonography recordings by trained readers at the ARIC Ultrasound Reading Center. At each visit, cIMT was computed as the average of 3 segments: the distal common carotid, the carotid artery bifurcation, and the proximal internal carotid arteries. Presence of carotid plaque was determined based on an abnormal wall thickness, shape, or wall texture. Audiometric 4-frequency pure tone average (PTA) was measured and calculated for the better-hearing ear and modeled as a continuous variable. Linear regression estimated the association between cIMT and carotid plaque with hearing, adjusting for age, sex, race and study center, education level, body mass index (calculated as weight in kilograms divided by height in meters squared), smoking status, hypertension, cholesterol levels, diabetes, and exposure to occupational noise. Missing data (exposure and covariates) were imputed with multiple imputation by chained equations. Data analyses were performed from April 6 to July 13, 2022.

Main Outcomes and Measures

Hearing loss assessed using 4-frequency (0.5, 1.0, 2.0, and 4.0 kilohertz) PTA for both ears and carotid plaque at visit 4 and mean cIMT from visit 1 to visit 4.

Results

Among a total of 3594 participants (mean [SD] age at visit 4, 59.4 [4.6] years; 2146 [59.7%] female; 819 [22.8%] Black and 2775 [77.2%] White individuals), fully adjusted models indicated that an additional 0.1 mm higher mean cIMT was associated with 0.59 dB (95% CI, 0.17 to 1.02 dB) higher PTA. Compared with participants without carotid plaque, plaque presence was associated with 0.63 dB (95% CI, -0.57 to 1.84 dB) higher PTA.

Conclusion and Relevance

The findings of this cross-sectional study with temporal analyses of a cohort with the ongoing ARIC study found that subclinical atherosclerosis in midlife was associated with worse hearing in older adulthood. Prevention and control of carotid atherosclerosis during middle age may positively affect the hearing health of older adults.

Hearing Health Outcomes as a Function of Age, Gender, and Diversity

The United States does not ensure equitable access to hearing health care for all age groups, largely because these services are costly and even unobtainable in some places. Barriers to care are discussed within a context of the social determinants of health, under-representativeness of hearing-care professionals from historically marginalized communities, older adults and age-related hearing loss, and associated health conditions. The MarkeTrak 2022 study generated a sample of 15,138 respondents with information on 43,597 individuals. Data analysis revealed that self-reported hearing difficulty appears to increase with age with a rate of 12.4% for adults 18 years of age and older. A substantial proportion of individuals with hearing difficulty assumed that their problem was age-related, followed by exposure to loud sound and noise. Individuals with hearing difficulty were nearly three to four times more likely to have tinnitus, cognitive problems, and issues with balance and falling than those with no hearing problems. Self-reported hearing difficulty was lower for historically marginalized groups (7%) than for the White population (12%). Recommendations are presented to reduce the burden of hearing difficulty and hearing aid deserts for rural and urban populations.

Impact of the Soundscape on the Physical Health and the Perception of Senior Adults in Senior Care Facilities

Purpose:

To explore the impact of different acoustic stimuli of varying sound pressure levels on physical responses and the perception of senior adults.

Background:

Noise-related health problems have been gaining increased attention as studies have shown an association with negative impacts on physiological parameters resulting in cardiovascular morbidity and mortality. However, a gap in knowledge exists in exploring the impact of exposure to sound recordings in the actual environment on physiological measurements.

Methods:

Five acoustic stimuli were recorded in real life and 120 senior adults listened to them in a sound treated room to analyze the impacts of low-, middle-, and high-decibel sounds on their heart rate, blood pressure, and perception. The physical responses, heart rate, and blood pressure were measured during the sound exposure, and questionnaires were administered afterward.

Results:

Exposure to different sounds resulted in fluctuations and an inconsistent trend in heart rate, systolic pressure, and diastolic pressure. According to the physical measures and subjective evaluations, sport sounds and traffic noise were given the lowest rating for preference, while music was perceived as the most comfortable.

Conclusions:

A sound pressure level below 55–65 dB(A) correlates with increased comfort and less increase in heart rate and blood pressure. Senior adults with normal hearing preferred and were most comfortable with music, while those with severe hearing impairment preferred entertainment sounds the most.

Analytical methods for correlated data arising from multicenter hearing studies

In epidemiological hearing studies, estimating the association between exposures and hearing loss using audiometrically-assessed hearing measurements is challenging due to the complex correlation structure in the clustered data, with clusters formed by the two ears of the same individual and the testing site and audiologist. We propose a linear mixed-effects model to take into account the multilevel correlation structures of the data. Both theoretically and in simulation studies, we compare single-ear linear regression models commonly used in published hearing loss studies with the proposed both-ears linear mixed models properly accounting for the multi-level correlations. Our findings include (1) when there are only participant-level covariates, the worse-ear linear regression models produce unbiased but typically less efficient estimators than the both-ear and average-ear approaches; (2) when there are ear-level confounders, the worse-ear method may lead to biased estimators and the average-ear method produces unbiased but typically less efficient estimators than the both-ear method; (3) the both-ear method may gain efficiency when additionally adjusting for testing sites and audiologists. As an illustrative example, we applied the single-ear and both-ear methods to assess aspirin-hearing association in the Nurses' Health Study II.

Documentation of Peripheral Auditory Function in Studies of the Auditory P300 Response

Abstract. A critical review was conducted to examine whether the peripheral hearing status of participants with neurological and psychological disorders was documented in published clinical studies of the auditory P300 response. Literature searches were conducted with three databases: PubMed, PsycINFO, and Scopus. Studies of participants with seven neurological or psychological disorders were included in the study. Each disorder was coupled with the main search phrase in separate searches on each database. Of the total 102 papers which met the inclusion criteria, the majority (64%) did not describe the peripheral hearing sensitivity of participants. In this review with studies that included participants at risk for hearing impairment, particularly age-related hearing loss, only a single publication adequately described formal hearing evaluation. Peripheral hearing status is rarely defined in studies of the P300 response. The inclusion of participants with a hearing loss likely affects the validity of findings for these studies. We recommend formal hearing assessment prior to inclusion of participants in studies of the auditory P300 response. The findings of this study may increase the awareness among researchers outside the field of audiology of the effects of peripheral hearing loss on the auditory P300.

Both-Ear Method for the Analysis of Audiometric Data

OBJECTIVE

Single-ear hearing measurements, such as better-ear, worse-ear or left/right ear, are often used as outcomes in auditory research, yet, measurements in the two ears of the same individual are often strongly but not perfectly correlated. We propose a both-ear method using the Generalized Estimating Equation approach for analysis of correlated binary ear data to evaluate determinants of ear-specific outcomes that includes information from both ears of the same individual.

DESIGN

We first theoretically evaluated bias in odds ratio (OR) estimates based on worse-ear and better-ear hearing outcomes. A simulation study was conducted to compare the finite sample performances of single-ear and both-ear methods in logistic regression models. As an illustrative example, the single-ear and both-ear methods were applied to estimate the association of Dietary Approaches to Stop Hypertension adherence scores with hearing threshold elevation among 3135 women, aged 48 to 68 years, in the Nurses' Health Study II.

RESULTS

Based on statistical theories, the worse-ear and better-ear methods could bias the OR estimates. The simulation results led to the same conclusion. In addition, the simulation results showed that the both-ear method had satisfactory finite sample performance and was more efficient than the single-ear method. In the illustrative example, the confidence intervals of the estimated ORs for the association of Dietary Approaches to Stop Hypertension scores and hearing threshold elevation using the both-ear method were narrower, indicating greater precision, than for those obtained using the other methods.

CONCLUSIONS

The worse-ear and better-ear methods may lead to biased estimates, and the left/right ear method typically results in less-efficient estimates. In certain settings, the both-ear method using the Generalized Estimating Equation approach for analyses of audiometric data may be preferable to the single-ear methods.

Tobacco, but Neither Cannabis Smoking Nor Co-Drug Use, Is Associated With Hearing Loss in the National Health and Nutrition Examination Survey, 2011 to 2012 and 2015 to 2016

INTRODUCTION

A relationship between tobacco smoking and hearing loss has been reported; associations with cannabis smoking are unknown. In this cross-sectional population-based study, we examined relationships between hearing loss and smoking (tobacco, cannabis, or co-drug use).

METHODS

We explored the relationship between hearing loss and smoking among 2705 participants [mean age = 39.41 (SE: 0.36) years] in the National Health and Nutrition Examination Survey (2011 to 12; 2015 to 16). Smoking status was obtained via questionnaire; four mutually exclusive groups were defined: nonsmokers, current regular cannabis smokers, current regular tobacco smokers, and co-drug users. Hearing sensitivity (0.5 to 8 kHz) was assessed, and two puretone averages (PTAs) computed: low- (PTA 0.5,1,2 ) and high-frequency (PTA 3,4,6,8 ). We defined hearing loss as threshold >15 dB HL. Multivariable logistic regression was used to examine sex-specific associations between smoking and hearing loss in the poorer ear (selected based on PTA 0.5,1,2 ) adjusting for age, sex, race/ethnicity, hypertension, diabetes, education, and noise exposure with sample weights applied.

RESULTS

In the age-sex adjusted model, tobacco smokers had increased odds of low- and high-frequency hearing loss compared with non-smokers [odds ratio (OR) = 1.58, 95% confidence ratio (CI): 1.05 to 2.37 and OR = 1.97, 95% CI: 1.58 to 2.45, respectively]. Co-drug users also had greater odds of low- and high-frequency hearing loss [OR = 2.07, 95% CI: 1.10 to 3.91 and OR = 2.24, 95% CI: 1.27 to 3.96, respectively]. In the fully adjusted multivariable model, compared with non-smokers, tobacco smokers had greater odds of high-frequency hearing loss [multivariable adjusted odds ratio = 1.64, 95% CI: 1.28-2.09]. However, in the fully adjusted model, there were no statistically significant relationships between hearing loss (PTA 0.5,1,2 or PTA 3,4,6,8 ) and cannabis smoking or co-drug use.

DISCUSSION

Cannabis smoking without concomitant tobacco consumption is not associated with hearing loss. However, sole use of cannabis was relatively rare and the prevalence of hearing loss in this population was low, limiting generalizability of the results. This study suggests that tobacco smoking may be a risk factor for hearing loss but does not support an association between hearing loss and cannabis smoking. More definitive evidence could be derived using physiological measures of auditory function in smokers and from longitudinal studies.

Hearing Loss in Cancer Patients with Skull Base Tumors Undergoing Pencil Beam Scanning Proton Therapy: A Retrospective Cohort Study

To assess the incidence and severity of changes in hearing threshold in patients undergoing high-dose pencil-beam-scanning proton therapy (PBS-PT). This retrospective cohort study included fifty-one patients (median 50 years (range, 13–68)) treated with PBS-PT for skull base tumors. No chemotherapy was delivered. Pure tone averages (PTAs)were determined before (baseline) and after PBS-PT as the average hearing thresholds at frequencies of 0.5, 1, 2, and 4 kHz. Hearing changes were calculated as PTA differences between pre-and post-PBS-PT. A linear mixed-effects model was used to assess the relationship between the PTA at the follow-up and the baseline, the cochlea radiation dose intensity, the increased age, and the years after PBS-PT. Included patients were treated for chordoma (n = 24), chondrosarcoma (n = 9), head and neck tumors (n = 9), or meningioma (n = 3), with a mean tumor dose of 71.1 Gy (RBE) (range, 52.0–77.8), and a mean dose of 37 Gy (RBE) (range, 0.0–72.7) was delivered to the cochleas. The median time to the first follow-up was 11 months (IQR, 5.5–33.7). The PTA increased from a median of 15 dB (IQR 10.0–25) at the baseline to 23.8 (IQR 11.3–46.3) at the first follow-up. In the linear mixed-effect model, the baseline PTA (estimate 0.80, 95%CI 0.64 to 0.96, p ≤ 0.001), patient’s age (0.30, 0.03 to 0.57, p = 0.029), follow-up time (2.07, 0.92 to 3.23, p ≤ 0.001), and mean cochlear dose in Gy (RBE) (0.34, 0.21 to 0.46, p ≤ 0.001) were all significantly associated with an increase in PTA at follow-up. The applied cochlear dose and baseline PTA, age, and time after treatment were significantly associated with hearing loss after proton therapy.

Musicianship-Related Structural and Functional Cortical Features Are Preserved in Elderly Musicians

Background

Professional musicians are a model population for exploring basic auditory function, sensorimotor and multisensory integration, and training-induced neuroplasticity. The brain of musicians exhibits distinct structural and functional cortical features; however, little is known about how these features evolve during aging. This multiparametric study aimed to examine the functional and structural neural correlates of lifelong musical practice in elderly professional musicians.

Methods

Sixteen young musicians, 16 elderly musicians (age >70), and 15 elderly non-musicians participated in the study. We assessed gray matter metrics at the whole-brain and region of interest (ROI) levels using high-resolution magnetic resonance imaging (MRI) with the Freesurfer automatic segmentation and reconstruction pipeline. We used BrainVoyager semiautomated segmentation to explore individual auditory cortex morphotypes. Furthermore, we evaluated functional blood oxygenation level-dependent (BOLD) activations in auditory and non-auditory regions by functional MRI (fMRI) with an attentive tone-listening task. Finally, we performed discriminant function analyses based on structural and functional ROIs.

Results

A general reduction of gray matter metrics distinguished the elderly from the young subjects at the whole-brain level, corresponding to widespread natural brain atrophy. Age- and musicianship-dependent structural correlations revealed group-specific differences in several clusters including superior, middle, and inferior frontal as well as perirolandic areas. In addition, the elderly musicians exhibited increased gyrification of auditory cortex like the young musicians. During fMRI, the elderly non-musicians activated predominantly auditory regions, whereas the elderly musicians co-activated a much broader network of auditory association areas, primary and secondary motor areas, and prefrontal and parietal regions like, albeit weaker, the young musicians. Also, group-specific age- and musicianship-dependent functional correlations were observed in the frontal and parietal regions. Moreover, discriminant function analysis could separate groups with high accuracy based on a set of specific structural and functional, mainly temporal and occipital, ROIs.

Conclusion

In conclusion, despite naturally occurring senescence, the elderly musicians maintained musicianship-specific structural and functional cortical features. The identified structural and functional brain regions, discriminating elderly musicians from non-musicians, might be of relevance for the aging musicians’ brain. To what extent lifelong musical activity may have a neuroprotective impact needs to be addressed further in larger longitudinal studies.

Association of Cigarette Smoking Patterns Over 30 Years With Audiometric Hearing Impairment and Speech-in-Noise Perception: The Atherosclerosis Risk in Communities Study

IMPORTANCE

The implications of cigarette smoking and smoking cessation for hearing impairment remain unknown. Many studies on this topic have failed to account for attrition among smokers in their findings.

OBJECTIVE

To assess the association of cigarette smoking patterns with audiometric and speech-in-noise hearing measures among participants of the Atherosclerosis Risk in Communities Study.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study included participants of the Atherosclerosis Risk in Communities Study from 4 US communities. The analysis includes data from visit 1 (1987-1989) through visit 6 (2016-2017); data were analyzed from March 16 through June 25, 2021. Audiometric hearing and speech-in-noise testing was offered to all participants at visit 6. Participants with incomplete audiometric data or missing data for educational level, body mass index, drinking status, a diabetes or hypertension diagnosis, or occupational noise were excluded. In addition, individuals were excluded if they self-reported as having other than Black or White race and ethnicity, or if they self-reported as having Black race or ethnicity and lived in 2 predominantly White communities.

MAIN OUTCOMES AND MEASURES

Smoking behavior was classified from visit 1 (1987-1989) to visit 6 (2016-2017) using group-based trajectory modeling based on self-reported smoking status at each clinic visit. Hearing was assessed at visit 6. An audiometric 4-frequency (0.5, 1, 2, 4 kHz) pure-tone average (PTA) was calculated for the better-hearing ear and modeled as a continuous variable. Speech-in-noise perception was assessed via the Quick Speech-in-Noise Test (QuickSIN) and modeled continuously. Attrition during the 30 years of follow-up was addressed by inverse probability of attrition weighting.

RESULTS

A total of 3414 participants aged 72 to 94 years (median [IQR] age, 78.8 [76.0-82.9] years; 2032 [59.5%] women) when hearing was measured at visit 6 (2016-2017) were included in the cohort; 766 (22.4%) self-identified as Black and 2648 (77.6%) as White individuals. Study participants were classified into 3 smoking groups based on smoking behavior: never or former smoking at baseline (n = 2911 [85.3%]), quit smoking during the study period (n = 368 [10.8%]), and persistent smoking (n = 135 [4.0%]). In fully adjusted models, persistent smoking vs never or former smoking was associated with an average 2.69 (95% CI, 0.56-4.81) dB higher PTA (worse hearing) and 1.42 (95% CI, -2.29 to -0.56) lower QuickSIN score (worse performance). Associations were stronger when accounting for informative attrition during the study period (3.53 [95% CI, 1.14-5.93] dB higher PTA; 1.46 [95% CI, -2.52 to -0.41] lower QuickSIN scores). Smoking cessation during the study (vs never or former smoking) was not associated with changes in hearing.

CONCLUSIONS AND RELEVANCE

In this cross-sectional study, persistent smoking was associated with worse audiometric hearing and speech-in-noise perception. Hearing measures among participants who quit smoking during the study period did not differ from those for never or former smokers, indicating that smoking cessation (as opposed to persistent smoking) may have benefits for hearing health.

Examining Delayed Recall in Cochlear Implant Users Using the Montreal Cognitive Assessment, California Verbal Learning Test, Third Edition, and Item Specific Deficit Approach: Preliminary Results

Purpose: Recent studies using the Montreal Cognitive Assessment (MoCA) suggest delayed recall is challenging for cochlear implant (CI) users. To better understand the underlying processes associated with delayed recall in CI users, we administered the MoCA and the California Verbal Learning Test, Third Edition (CVLT-3), which provides a more comprehensive assessment of delayed recall ability.

Methods: The MoCA and CVLT-3 were administered to 18 high-performing CI users. For the CVLT-3, both the traditional scoring and a newer scoring method, the Item-Specific Deficit Approach (ISDA), were employed.

Results: The original MoCA score and MoCA delayed recall subtest score did not relate to performance on any CVLT-3 measures regardless of scoring metric applied (i.e., traditional or ISDA). Encoding performance for both the CVLT-3 and ISDA were related. Consolidation, which is only distinctly defined by the ISDA, related to CVLT-3 cued delay recall performance but not free delay recall performance. Lastly, ISDA retrieval only related to CVLT-3 measures when modified.

Conclusion: Performance on the MoCA and CVLT-3 in a high performing CI patient population were not related. We demonstrate that the ISDA can be successfully applied to CI users for the quantification and characterization of delayed recall ability; however, future work addressing lower performing CI users, and comparing to normal hearing controls is needed to determine the extent of potential translational applications. Our work also indicates that a modified ISDA retrieval score may be beneficial for evaluating CI users although additional work addressing the clinical relevance of this is still needed.

The impact of cardiovascular diseases on hearing deterioration: a 13-year follow-up study

OBJECTIVE

To study the impact of cardiovascular diseases (CVDs) on hearing deterioration among ageing adults in a longitudinal setting. Furthermore, to describe the pure tone threshold changes at the 0.125-8 kHz frequency range over 13 years.

DESIGN

A population-based follow-up study.

STUDY SAMPLE

A random sample of 850 adults, of whom 559 participated in the follow-up study. Otological examination, a structured interview, and pure tone audiometry were conducted. Multivariate regression models were used to estimate the effect of CVD (participants had at least one cardiovascular condition) on hearing deterioration of the better ear hearing level (BEHL), defined as a change in the pure-tone average (PTA) of the frequencies 0.5, 1, 2, and 4 kHz and separately at the lower (0.125, 0.25, and 0.5 kHz) and higher (4, 6, and 8 kHz) frequencies.

RESULTS

In the multivariable-adjusted analysis, the BEHL change at 13 years was 0.7 dB greater among participants with CVD (p = 0.3). The mean BEHL change during the 13-year follow-up was 12.0 dB (95% CI 11.4-12.6) among all participants.

CONCLUSIONS

No significant association between CVD and hearing threshold changes was found.

Hearing Function: Identification of New Candidate Genes Further Explaining the Complexity of This Sensory Ability

To date, the knowledge of the genetic determinants behind the modulation of hearing ability is relatively limited. To investigate this trait, we performed Genome-Wide Association Study (GWAS) meta-analysis using genotype and audiometric data (hearing thresholds at 0.25, 0.5, 1, 2, 4, and 8 kHz, and pure-tone averages of thresholds at low, medium, and high frequencies) collected in nine cohorts from Europe, South-Eastern USA, Caucasus, and Central Asia, for an overall number of ~9000 subjects. Three hundred seventy-five genes across all nine analyses were tagged by single nucleotide polymorphisms (SNPs) reaching a suggestive p-value (p < 10⁻⁵). Amongst these, 15 were successfully replicated using a gene-based approach in the independent Italian Salus in the Apulia cohort (n = 1774) at the nominal significance threshold (p < 0.05). In addition, the expression level of the replicated genes was assessed in published human and mouse inner ear datasets. Considering expression patterns in humans and mice, eleven genes were considered particularly promising candidates for the hearing function: BNIP3L, ELP5, MAP3K20, MATN2, MTMR7, MYO1E, PCNT, R3HDM1, SLC9A9, TGFB2, and YTHDC2. These findings represent a further contribution to our understanding of the genetic basis of hearing function and its related diseases.

Macrolide-associated ototoxicity: a cross-sectional and longitudinal study to assess the association of macrolide use with tinnitus and hearing loss

BACKGROUND

Macrolides are widely prescribed antibiotics for many different indications. However, there are concerns about adverse effects such as ototoxicity.

OBJECTIVES

To investigate whether macrolide use is associated with tinnitus and hearing loss in the general population.

METHODS

Cross-sectional (n = 4286) and longitudinal (n = 636) analyses were performed within the population-based Rotterdam Study. We investigated with multivariable logistic regression models the association between macrolides and tinnitus, and with multivariable linear regression models the association between macrolides and two different hearing thresholds (both ears, averaged over 0.25, 0.5, 1, 2, 4 and 8 kHz and 2, 4 and 8 kHz). Both regression models were adjusted for age, sex, systolic blood pressure, alcohol, smoking, BMI, diabetes, education level, estimated glomerular filtration rate and other ototoxic or tinnitus-generating drugs. Cumulative exposure to macrolides was categorized according to the number of dispensed DDDs and duration of action.

RESULTS

In the fully adjusted model, ever use of macrolides was associated with a 25% higher likelihood of prevalent tinnitus (OR = 1.25; 95% CI 1.07-1.46). This association was more prominent in participants with a cumulative dose of more than 14 DDDs and among users of intermediate- or long-acting macrolides. Macrolide use in between both assessments was associated with more than a 2-fold increased risk on incident tinnitus. No general association between macrolides and hearing loss was observed. A borderline significant higher hearing threshold in very recent users (≤3 weeks) was found.

CONCLUSIONS

Macrolide use was significantly associated with both prevalent and incident tinnitus. Macrolide-associated tinnitus was likely cumulative dose-dependent.

Association Between Nonoptimal Blood Pressure and Cochlear Function

OBJECTIVES

The association between hearing loss and risk factors for cardiovascular disease, including high blood pressure (BP), has been evaluated in numerous studies. However, data from population- and laboratory-based studies remain inconclusive. Furthermore, most prior work has focused on the effects of BP level on behavioral hearing sensitivity. In this study, we investigated cochlear integrity using distortion product otoacoustic emissions (DPOAEs) in persons with subtle elevation in BP levels (nonoptimal BP) hypothesizing that nonoptimal BP would be associated with poorer cochlear function.

DESIGN

Sixty individuals [55% male, mean age = 31.82 (SD = 11.17) years] took part in the study. The authors measured pure-tone audiometric thresholds from 0.25 to 16 kHz and computed four pure-tone averages (PTAs) for the following frequency combinations (in kHz): PTA0.25, 0.5, 0.75, PTA1, 1.5, 2, 3, PTA4, 6, 8, and PTA10, 12.5, 16. DPOAEs at the frequency 2f1-f2 were recorded for L1/L2 = 65/55 dB SPL using an f2/f1 ratio of 1.22. BP was measured, and subjects were categorized as having either optimal BP (systolic/diastolic <120 and <80 mm Hg) or nonoptimal BP (systolic ≥120 or diastolic ≥80 mm Hg or use of antihypertensives). Between-group differences in behavioral thresholds and DPOAE levels were evaluated using 95% confidence intervals. Pearson product-moment correlations were run to assess the relationships between: (1) thresholds (all four PTAs) and BP level and (2) DPOAE [at low (f2 ≤ 2 kHz), mid (f2 > 2 kHz and ≤10 kHz), and high (f2 > 10 kHz) frequency bins] and BP level. Linear mixed-effects models were constructed to account for the effects of BP status, stimulus frequency, age and sex on thresholds, and DPOAE amplitudes.

RESULTS

Significant positive correlations between diastolic BP and all four PTAs and systolic BP and PTA0.25, 0.5, 0.75 and PTA4, 6, 8 were observed. There was not a significant effect of BP status on hearing thresholds from 0.5 to 16 kHz after adjustment for age, sex, and frequency. Correlations between diastolic and systolic BP and DPOAE levels were statistically significant at the high frequencies and for the relationship between diastolic BP and DPOAE level at the mid frequencies. Averaged across frequency, the nonoptimal BP group had DPOAE levels 1.50 dB lower (poorer) than the optimal BP group and differences were statistically significant (p = 0.03).

CONCLUSIONS

Initial findings suggest significant correlations between diastolic BP and behavioral thresholds and diastolic BP and mid-frequency DPOAE levels. However, adjusted models indicate other factors are more important drivers of impaired auditory function. Contrary to our hypothesis, we found that subtle BP elevation was not associated with poorer hearing sensitivity or cochlear dysfunction. We consider explanations for the null results. Greater elevation in BP (i.e., hypertension itself) may be associated with more pronounced effects on cochlear function, warranting further investigation. This study suggests that OAEs may be a viable tool to characterize the relationship between cardiometabolic risk factors (and in particular, stage 2 hypertension) and hearing health.

A New Type of Wireless Transmission Based on Digital Direct Modulation for Use in Partially Implantable Hearing Aids

In this study, we developed a new type of wireless transmission system for use in partially implantable hearing aids. This system was designed for miniaturization and low distortion, and features direct digital modulation. The sigma-delta output, which has a high SNR due to oversampling and noise shaping technology, is used as the data signal and is transmitted using a wireless transmission system to the implant unit through OOK without restoration as an audio signal, thus eliminating the need for additional circuits (i.e., LPF and a reference voltage supply circuit) and improving the ease of implantation and reliability of the circuit. We selected a carrier frequency of 27 MHz after analysis of carrier attenuation by human tissue, and designed the communication coil with reference to both the geometry and required communication distance. Circuit design and simulation for wireless transmission were performed using Multisim 13.0. The system was fabricated based on the circuit design; the size of the device board was 13 mm × 13 mm, the size of the implanted part was 9 mm × 9 mm, the diameter of the transmitting/receiving coil was 26 mm, and the thicknesses of these coils were 0.5 and 0.3 mm, respectively. The difference (error) between the detected and simulation waveforms was about 5%, and was thought to be due to the tolerances of the fabricated communication coil and elements (resistors, capacitors, etc.) used in the circuit configuration of the system. The number of windings was reduced more than 9-fold compared to the communication coil described by Taghavi et al. The measured THD was <1% in the frequency band from 100 Hz to 10 kHz, thus easily meeting the standard specification for hearing aids.

Self-reported and cotinine-verified smoking and increased risk of incident hearing loss

We examined the associations of smoking status and urinary cotinine levels, an objective measure of smoking, with the development of new-onset HL. This cohort study was performed in 293,991 Korean adults free of HL who underwent a comprehensive screening examination and were followed for up to 8.8 years. HL was defined as a pure-tone average of thresholds at 0.5, 1.0, and 2.0 kHz ≥ 25 dB in both ears. During a median follow-up of 4.9 years, 2286 participants developed new-onset bilateral HL. Self-reported smoking status was associated with an increased risk of new-onset bilateral HL. Multivariable-adjusted HRs (95% CIs) for incident HL comparing former smokers and current smokers to never-smokers were 1.14 (1.004-1.30) and 1.40 (1.21-1.61), respectively. Number of cigarettes, pack-years, and urinary cotinine levels were consistently associated with incident HL. These associations were similarly observed when introducing changes in smoking status, urinary cotinine, and other confounders during follow-up as time-varying covariates. In this large cohort of young and middle-aged men and women, smoking status based on both self-report and urinary cotinine level were independently associated with an increased incidence of bilateral HL. Our findings indicate smoking is an independent risk factor for HL.

Modeling Hearing Loss Progression and Asymmetry in the Older Old: A National Population-Based Study

OBJECTIVE

The progression and asymmetry of age-related hearing loss has not been well characterized in those 80 years of age and older because public datasets mask upper extremes of age to protect anonymity. We aim to characterize the progression, severity, and asymmetry of hearing loss in those 80 years of age and older using a representative, national database.

METHODS

Cross-sectional, multicentered U.S. epidemiologic analysis using the National Health and Nutrition Examination Survey (NHANES) 2005 to 2006, 2009 to 2010, and 2011 to 2012 cycles. Subjects included noninstitutionalized, civilian adults aged 80 years and older (n = 621). Federal security clearance was granted to access publicly restricted age data. Outcome measures included pure-tone average (PTA) air conduction thresholds and the 4-frequency PTA.

RESULTS

Six hundred and twenty-one subjects were 80 years old or older (mean = 84.2 years, range = 80-104 years), representing 10,600,197 Americans. The average PTA was 38.9 dB (95% confidence interval [CI] = 37.8, 40.0). Hearing loss exhibited constant acceleration across the adult lifespan at a rate of 0.0052 dB/year2 (95% CI = 0.0049, 0.0055). This model predicted mean PTA within 2 dB of accuracy for most ages between 20 and 100 years. From age 80 years to approximately 100 years, the average PTA difference between the better and worse ear was 6.75 dB (95% CI = 5.8, 7.1). This asymmetry was relatively constant (i.e., nonsignificant linear regression coefficient of asymmetry over age = 0.07 [95% CI = -0.01, 0.2]).

CONCLUSION

Hearing loss steadily and predictably accelerates across the adult lifespan to at least age 100 years, becoming near universal. These population-level statistics will guide treatment and policy recommendations for hearing health in the older old.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:879-884, 2021.

Phenotype of the Aging-Dependent Spontaneous Onset of Hearing Loss in DBA/2 Mice

Simple Summary

In this study, we confirmed the changes in hearing function and inner ear structure over a long period of time in DBA/2 mice, a laboratory animal model suitable for studying hearing loss. We believe that our study is the first to report findings regarding hearing function and structural changes in DBA/2 mice aged ≥34 weeks. These results are of significance for researchers and the scientific community using laboratory animal models.

Abstract

DBA/2 mice are a well-known animal model for hearing loss developed due to intrinsic properties of these animals. However, results on the phenotype of hearing loss in DBA/2 mice have been mainly reported at an early stage in mice aged ≤7 weeks. Instead, the present study evaluated the hearing ability at 5, 13, and 34 weeks of age using DBA/2korl mice. Auditory brainstem response test was performed at 8–32 KHz at 5, 13, and 34 weeks of age, and hearing loss was confirmed to be induced in a time-dependent manner. In addition, histopathological evaluation at the same age confirmed the morphological damage of the cochlea. The findings presented herein are the results of the long-term observation of the phenotype of hearing loss in DBA/2 mice and can be useful in studies related to aging-dependent hearing loss.

Association between Speech Recognition in Noise and Risk Factors of Cardiovascular Disease

INTRODUCTION

Risk factors for cardiovascular disease (CVD) are associated with sensorineural hearing loss. CVD risk factors are known to cluster and interact, thereby increasing the cumulative risk for CVD. Previously, using the database of the Netherlands Longitudinal Study on Hearing (NL-SH), an association was found between a history of smoking and an increased decline in speech recognition in noise over 10 years of follow-up. Prospectively limited data are available on the association between CVD risk factors, interactions of these risk factors, and hearing loss. In this study, data from the NL-SH were used to study the association between CVD risk factors and speech recognition in noise longitudinally.

METHODS

Baseline, 5-year, and 10-year follow-up data of the NL-SH were included. The NL-SH is a web-based prospective cohort study which started in 2006. Participants were aged 18-70 years at baseline. Speech recognition in noise was determined with an online digit-triplet speech-in-noise test. In addition, participants completed online questionnaires on demographic, lifestyle, and health-related characteristics. The association of the ability to recognize speech in noise with CVD risk factors (i.e., obesity, rheumatoid arthritis [RA], hypertension, diabetes mellitus, and dyslipidemia) was analyzed longitudinally. We also analyzed the interaction between these risk factors (including age, sex, and history of smoking) and speech recognition in noise.

RESULTS

None of the CVD risk factors or interactions of 2 CVD risk factors was significantly associated with a decline in SRT over time. Obesity (p = 0.016), RA (p = 0.027), and hypertension (p = 0.044) were associated with overall higher (more unfavorable) SRTs. No overall interactions between CVD risk factors were found.

CONCLUSION

Obesity, RA, and hypertension were overall associated with a higher SRT, but no longitudinal associations between these or other CVD factors with SRTs were found. Also, no interactions between 2 CVD risk factors and SRTs were found. Although no longitudinal associations between CVD risk factors and decline in SRTs were found, clinicians should be alert about the concurrent association between CVD risk factors and hearing loss.

Association Between Microvascular Retinal Signs and Age-Related Hearing Loss in the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS)

Importance

Given that age-related hearing loss is highly prevalent and treatable, understanding its causes may have implications for disease prevention.

Objective

To investigate whether microvascular retinal signs are associated with age-related hearing loss attributable to a hypothesized underlying shared pathologic entity involving microvascular disease.

Design, Setting, and Participants

The Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS) is a community-based prospective cohort study of 15 792 men and women aged 45 to 64 years at baseline. The ARIC-NCS participants returned for a fifth clinic visit in 2011-2013 and a sixth clinic visit in 2016-2017. Participants were recruited from 4 US communities (Washington County, Maryland; Forsyth County, North Carolina; Jackson, Mississippi; and Minneapolis suburbs, Minnesota). Participants included a subset of the ARIC-NCS cohort with complete covariate data who underwent retinal fundus photography at visit 5 (2011-2013) and completed hearing assessment at visit 6 (2016-2017) (N = 1458). Overall, 453 participants had diabetes; of those, 68 had retinopathy. Of 1005 participants without diabetes, 42 had retinopathy.

Exposures

Microvascular retinal signs included retinopathy, arteriovenous (AV) nicking, and generalized arteriolar narrowing measured using the central retinal arteriolar equivalent (CRAE).

Main Outcomes and Measures

Hearing was measured using the better-hearing ear pure-tone average (PTA) of air conduction speech thresholds (0.5, 1, 2, and 4 kHz). Multivariable-adjusted linear and ordered logistic regression was used to estimate the association between microvascular retinal signs and age-related hearing loss to describe the precision of the estimates and provide a plausible range for the true association.

Results

After full adjustment among 1458 individuals in the analytic cohort (mean [SD] age, 76.1 [5.0] years [age range, 67-90 years]; 825 women [56.6%]; 285 black [19.5%]), the difference in PTA per dB hearing level in persons with and without retinopathy was 2.21 (95% CI, -0.22 to 4.63), suggesting that retinopathy is associated with poorer hearing, although the width of the 95% CI prevents definitive conclusions about the strength of the observed association. Restricting the analysis to participants without diabetes, the difference in PTA associated with retinopathy was even greater (4.14; 95% CI, 0.10-8.17 dB hearing level), but the large width of the 95% CI prevents definitive conclusions about the association. In analyses quantifying the mean differences in hearing thresholds at individual frequencies by retinopathy status, the estimates trended toward retinopathy being associated, contrary to expectation, with better high-frequency hearing. At 8 kHz, the estimated difference in hearing thresholds in persons with retinopathy vs those without was -4.24 (95% CI, -7.39 to -1.09).

Conclusions and Relevance

In this population-based study, an association between the presence of microvascular retinal signs and hearing loss was observed, suggesting that retinopathy may have the potential to identify risk for hearing loss in persons without diabetes. The precision of these estimates is low; therefore, additional epidemiologic studies are needed to better define the degree of microvascular contributions to age-related hearing loss.

Hearing impairment is associated with cognitive function in community-dwelling older adults: A cross-sectional study

BACKGROUND

Hearing impairment (HI) is associated with dementia. However, the cognitive screening tasks effective in older community dwellers presenting with HI are unclear.

METHODS

We retrospectively and cross-sectionally investigated the associations between HI and cognitive function assessed with screening tasks using data from two healthcare check-up programs for community dwellers ≥65 years old in 2018. We examined demographics, risk factors, cognitive function, hearing condition, lifestyles, and self-care levels. Cognitive function was assessed using the clock drawing task and the delayed three words recall task. Hearing condition was assessed using questionnaires on the use of hearing aids and HI during conversation situations. Multivariate analysis was used to identify independent associations between HI and cognitive assessment tasks.

RESULTS

We analyzed 1602 eligible participants (61.9% women; 74.3 ± 6.5 years old). Hearing aid users (n = 90) were older (80 vs. 73 years, respectively; p < 0.001) and less likely to draw the clock correctly (71.1% vs. 80.1% years, respectively; p = 0.044) than non-hearing aid users. Multivariate logistic regression analysis showed that HI was associated with inability to draw the clock correctly (odds ratio 1.60, 95% confidence interval 1.12-2.26; p = 0.011), independent of age, living alone, memory impairment, and impaired self-care levels.

CONCLUSION

Hearing impairment is independently associated with cognitive decline assessed by the clock drawing task. The clock drawing task may be useful for identifying an increased risk of dementia in older subjects presenting with HI.

Making the Case for Research on Disease-Modifying Treatments to Tackle Post-lingual Progressive Sensorineural Hearing Loss

Hearing loss not only has a significant impact on the quality of life of patients and society, but its correlation with cognitive decline in an aging population will also increase the risk of incident dementia. While current management of hearing loss is focused on hearing rehabilitation (and essentially symptomatic), patients are suffering from the burden of progressive hearing loss before hearing aids or cochlear implants are fitted. Although these devices have a significant effect on speech understanding, they do not always lead to normal speech understanding, especially in noisy environments. A significant number of patients suffer from autosomal dominantly inherited disorders that can produce progressive sensorineural hearing loss. This includes DFNA9, a disorder caused by pathologic variants in the COCH gene that leads to post-lingual profound sensorineural hearing loss and bilateral vestibulopathy. Carriers of a pathogenic variant leading to DFNA9 can be diagnosed at the pre-symptomatic or early symptomatic stage which creates a window of opportunity for treatment. Preventing hearing loss from occurring or stabilizing progression would provide the opportunity to avoid hearing aids or cochlear implants and would be able to reduce the increased incidence of dementia. While innovative therapies for restoration of hearing have been studied for restoration of hearing in case of severe-to-profound sensorineural hearing loss and congenital hearing loss, further research is needed to study how we can modify disease progression in late-onset autosomal dominant hereditary sensorineural hearing loss. Recently, gene editing strategies have been explored in autosomal dominant disorders to disrupt dominant mutations selectively without affecting wild-type alleles.

Design of a dual-coil type electromagnetic actuator for implantable bone conduction hearing devices

BACKGROUND

This paper describes the design and implementation of a dual-coil type electromagnetic actuator for implantable bone conduction hearing devices.

OBJECTIVE

The structure of the proposed actuator was designed to generate maximum Lorentz force via the dual-coil method with a closed magnetic circuit. To satisfy the indications required by implantable bone conduction hearing devices, high output was generated within a specific frequency range using a vibrational membrane with a cantilever.

METHODS

The structure of the membrane consists of a fixed ring, a circular plate, and two cantilevers connected symmetrically. Variable elements of the vibrational membrane affecting the actuator frequency characteristics were analyzed through mathematical modeling and finite element analysis, based on the analysis used to derive the optimum structure of the vibrational membrane. The components of the actuator were fabricated through chemical etching and computer numerical control process, and the bone conduction actuator was fabricated through the precision assembly process.

RESULTS

The output characteristics of the implemented actuator were measured using a laser Doppler vibrometer. As a result of measurement, the proposed actuator generated mechanical resonance at 1.2 kHz.

CONCLUSIONS

By comparing the measured results with the finite element analysis results, we confirmed the validity of the proposed actuator design.