ABO blood group and cochlear function: evidence from a large sample size study.

OBJECTIVE: The present study investigated the effect of blood group on cochlear function in a large participant sample across different age groups. The study hypothesis was that participants with blood group O would show relatively reduced cochlear function as reflected in otoacoustic emission (OAE) measures. DESIGN: Data were collected from transient evoked otoacoustic emission (TEOAE), distortion product otoacoustic emission (DPOAE), DPOAE input/output (I/O) function, and spontaneous otoacoustic emission (SOAE) recordings. STUDY SAMPLE: Four hundred and sixty-three normal hearing adults aged 20-59 years among the four ABO blood groups participated in the study. RESULTS: TEOAE and DPOAE amplitudes did not reveal significant differences for participants with blood group O compared with participants with non-O blood groups. No significant differences in I/O function categories were found among participants with different blood groups. SOAE prevalence was also not significantly different across blood groups. However, previously reported age and gender differences for OAE variables were confirmed. CONCLUSIONS: Participants with blood group O were not found to have significantly reduced cochlear function, based on OAE measures. Results from the current study do not support the hypothesis that normal hearing individuals with different ABO blood groups differ in level of cochlear function.

Noise sensitivity associated with nonrestorative sleep in Chinese adults: a cross-sectional study.

BACKGROUND: Nonrestorative sleep is a common sleep disorder with a prevalence ranging from 1.4 to 35%, and is associated with various psychological and physical health issues. Noise exposure and noise sensitivity have been proposed to contribute to nonrestorative sleep. This study aimed to examine the relationships among noise, noise sensitivity, nonrestorative sleep, and physiological sleep parameters in Chinese adults. METHODS: A cross-sectional household survey was conducted with randomly selected Chinese adults based on a frame stratified by geographical districts and types of quarters in Hong Kong. We administered a battery of questionnaires, including the Nonrestorative Sleep Scale, the Weinstein Noise Sensitivity Scale, the ENRICHD Social Support Instrument, the Patient Health Questionnaire, and the Perceived Stress Scale to assess nonrestorative sleep, noise sensitivity, social support, somatic symptoms and stress, respectively. Anxiety and depression were evaluated by the Hospital Anxiety and Depression Scale while sociodemographic and lifestyle characteristics were assessed with an investigator-developed sheet. Nocturnal noise level and physiological sleep parameters were measured during nighttime for a week by noise dosimetry and actigraphy, respectively. A structured multiphase linear regression was conducted to estimate associations. RESULTS: A total of 500 adults (66.4% female) with an average age of 39 years completed this study. Bivariate regressions showed that age, marital status, occupation, family income, season, exercise, cola and soda consumption, social support, somatic symptoms, stress, depression, noise sensitivity, total sleep time, and awakenings were associated with nonrestorative sleep. In the multivariable analysis, family income, season, exercise, social support, somatic symptoms, stress, and depression remained associated with nonrestorative sleep. Specifically, a one-unit increase of noise sensitivity was associated with 0.08 increase in nonrestorative sleep (95% confidence interval [CI]: 0.01, 0.15, p = 0.023). Nocturnal noise was negatively associated with time in bed (b = - 1.65, 95% CI: - 2.77, - 0.52, p = 0.004), total sleep time (b = - 1.61, 95% CI: - 2.59, - 0.62, p = 0.001), and awakenings (b = - 0.16, 95% CI: - 0.30, - 0.03, p = 0.018), but was not associated with nonrestorative sleep. CONCLUSIONS: Nonrestorative sleep was predicted by noise sensitivity in addition to family income, season, exercise, social support, somatic symptoms, stress, and depression.

Indoor nocturnal noise is associated with body mass index and blood pressure: a cross-sectional study.

BACKGROUND: Studies have demonstrated that noise is associated with various health problems, such as obesity and hypertension. Although the evidence of the associations of noise with obesity and hypertension is inconsistent, there seems to be a stronger association of the latter. This study aimed to investigate the associations of noise with body mass index (BMI) and blood pressure in adults living in multi-story residential buildings. METHODS: A cross-sectional study was conducted in Hong Kong from February 2018 to September 2019. The Weinstein Noise Sensitivity Scale, Pittsburgh Sleep Quality Index, ENRICHD Social Support Instrument, Patient Health Questionnaire, Perceived Stress Scale, and Hospital Anxiety and Depression Scale were administered to the participants. BMI and blood pressure were assessed. Nocturnal noise exposure and total sleep duration were measured for a week. RESULTS: Five hundred adults (66.4% female), with an average age of 39 years (range: 18-80), completed the study. The average levels of nocturnal noise, BMI, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were 51.3 dBA, 22.2 kg/m2, 116.0 mmHg, and 75.4 mmHg, respectively. After adjusting for sociodemographic characteristics, nocturnal noise was associated with BMI (b = 0.54, 95% CI: 0.01 to 1.06, p = 0.045) and SBP (b = 2.90, 95% CI: 1.12 to 4.68, p = 0.001). No association was detected between nocturnal noise and DBP (b = 0.79, 95% CI: - 0.56 to 2.13, p = 0.253). Specifically, higher nocturnal noise was associated with higher BMI (b = 0.72, 95% CI: 0.07 to 1.38, p = 0.031) and SBP (b = 3.91, 95% CI: 2.51 to 5.31, p < 0.001) in females but only higher SBP (b = 3.13, 95% CI: 1.35 to 4.92, p < 0.001) in males. The association between noise and SBP remained significant (b = 2.41, 95% CI: 0.62 to 4.20, p = 0.008) after additionally adjusting for lifestyle, diagnosis of hypertension, psychometric constructs, and sleep. CONCLUSIONS: Indoor nocturnal noise was associated with BMI and blood pressure in females but only blood pressure in males. It is important to control nocturnal noise or use soundproofing materials in buildings to reduce noise exposure.

Effect of eye closure on speech recognition in noise: in light and in darkness.

OBJECTIVE: This study evaluated whether listening with an eye closure (EC) strategy improves speech recognition in noise (SRN) under different visual conditions. Previous research suggests EC may enhance activation of cortical systems involved in listening and attention. Study hypotheses were that EC listening leads to better SRN than eyes open listening, that listening in darkness leads to better SRN than in light, and EC listening leads to more improved SRN in light compared to darkness. DESIGN: SRN with the Cantonese Hearing in Noise Test (CHINT) under four conditions was assessed: (1) eyes open with lights on, (2) EC with lights on, (3) eyes open in darkened room, and (4) EC in darkened room. ANOVA determined potential differences among conditions and effect sizes were calculated. STUDY SAMPLE: Fifty-six young adults (age range 18-35 years) with bilaterally normal hearing. RESULTS: Significant effects for EC and presence/absence of an external visual stimulus on SRN were found. Post-hoc analysis found a statistically significant difference between eyes open and closed in light, with a large effect size, indicating EC resulted in the greatest improvement in SRN when in the presence of an external visual stimulus. However, differences compared with known CHINT inter-list variability lacked clinical importance. CONCLUSIONS: EC did significantly improve SRN and is a potential strategy for challenging listening situations when feasible, although no changes are needed for CHINT norms or testing procedures in relation to EC status.

Access to adults' hearing aids: policies and technologies used in eight countries.

As the proportion of older adults in the world's total population continues to grow, the adverse health outcomes of age-related hearing loss are becoming increasingly recognized. While research has shown that age-related hearing loss is the single greatest modifiable risk factor for dementia, use of hearing aids remains low worldwide, even in many middle- and high-income countries. Reasons for poor uptake of hearing aids are likely to involve a combination of factors, ranging from increasing costs of hearing aid technology to a widespread lack of insurance coverage. This article aims to identify the current state of access to hearing aids, focusing on eight middle- and high-income countries. We discuss how to facilitate greater access to hearing aids for patients by addressing changes in how devices are regulated, technological advancements in hearing devices, the need to adjust reimbursement schemes and the importance of adaptation among the community workforce for hearing-care.

Alors que la proportion de personnes âgées au sein de la population mondiale totale continue à croître, les effets néfastes sur la santé de la perte de l'acuité auditive liée à l'âge sont de plus en plus reconnus. Bien que la recherche ait démontré que la perte de l'acuité auditive liée à l'âge est le principal facteur de risque modifiable de la démence, l'utilisation de prothèses auditives reste limitée à l'échelle mondiale, y compris dans de nombreux pays à revenu intermédiaire et élevé. Les raisons de ce recours limité aux prothèses auditives tiennent probablement à une combinaison de facteurs qui vont des coûts croissants de la technologie des appareils auditifs à un manque généralisé de couverture médicale. Cet article vise à déterminer l'état actuel de l'accès aux prothèses auditives en se concentrant sur huit pays à revenu intermédiaire et élevé. Nous étudions comment permettre aux patients d'accéder plus facilement aux prothèses auditives en tenant compte de la réglementation applicable aux appareils, des progrès technologiques relatifs aux appareils auditifs, de la nécessité d'ajuster les systèmes de remboursement et de l'importance de l'adaptation au sein de la main-d'œuvre locale pour les soins auditifs.

A medida que la proporción de adultos mayores en la población total del mundo continúa creciendo, los resultados adversos para la salud de la pérdida de audición relacionada con la edad son cada vez más reconocidos. Aunque las investigaciones han demostrado que la pérdida de audición relacionada con la edad es el mayor factor de riesgo modificable para la demencia, el uso de audífonos sigue siendo bajo en todo el mundo, incluso en muchos países de ingresos medios y altos. Las causas de la escasa aceptación de los audífonos pueden ser una combinación de factores, que van desde el aumento de los costes de la tecnología de los audífonos hasta la falta generalizada de cobertura de seguro. Este artículo pretende identificar el estado actual del acceso a los audífonos, centrándose en ocho países de ingresos medios y altos. Discutimos cómo facilitar un mayor acceso a los audífonos para los pacientes abordando los cambios en cómo se regulan los dispositivos, los avances tecnológicos en los audífonos, la necesidad de ajustar los esquemas de reembolso y la importancia de la adaptación entre los trabajadores de la comunidad para el cuidado de la audición.

ABO Blood Group and Cochlear Status: Otoacoustic Emission Markers.

OBJECTIVES: There are an increasing number of research studies examining the effects of ABO blood group on susceptibility to disease. However, little is known regarding the potential relationship between blood group and hearing. Higher risk of noise-induced hearing loss was linked to blood group O in several occupational health studies. Based on this finding, a recent study of cochlear status was conducted with normal-hearing female participants representing equal numbers of the four blood groups in the ABO blood group system. ABO blood group was associated with cochlear characteristics, including the prevalence of spontaneous otoacoustic emissions (SOAEs) and the amplitudes of transient-evoked otoacoustic emissions (TEOAEs) and distortion-product otoacoustic emissions (DPOAEs). Females with blood group O showed significantly lower amplitudes of DPOAEs at some frequencies and lower prevalence of SOAEs compared with participants with blood group B. There was a general trend of reduced TEOAE and DPOAE amplitudes in blood group O individuals compared with participants with non-O blood groups. Following from this finding, and based on known sex differences in otoacoustic emission characteristics, the present study examined the possible effects of blood group on otoacoustic emission status in males. DESIGN: Sixty clinically normal-hearing males aged between 18 and 26 years, with equal numbers of participants in each of the ABO blood groups, were recruited by purposive sampling. SOAE, DPOAE, and linear and nonlinear TEOAE recordings were collected from all participants, as well as tympanometric data related to external and middle ear characteristics. RESULTS: The male blood group O participants exhibited significantly lower SOAE prevalence and reduced amplitudes of DPOAEs on average, and in the midfrequency range, than participants with blood group B, and lower nonlinear and linear TEOAE amplitudes at a number of frequencies when compared with participants with blood groups A and B. A consistent trend of lower TEOAE and DPOAE response amplitudes was observed in participants with blood group O. No significant difference was noted among blood groups for outer or middle ear characteristics. CONCLUSIONS: These results were consistent with previous findings of reduced otoacoustic emission responses in female blood group O individuals. Results support the hypothesis that blood group O individuals may be at increased risk of cochlear damage from noise exposure. Further investigation on the potential link between ABO blood group and auditory status, including potentially differential effects of noise exposure on cochlear function, is needed. The possible effects of ABO blood group on other aspects of audition, such as hearing sensitivity, speech understanding, and auditory processing, should be evaluated.

Hearing Loss in Children With Otitis Media With Effusion: Actual and Simulated Effects on Speech Perception.

OBJECTIVE: Conductive hearing loss simulations have attempted to estimate the speech-understanding difficulties of children with otitis media with effusion (OME). However, the validity of this approach has not been evaluated. The research aim of the present study was to investigate whether a simple, frequency-specific, attenuation-based simulation of OME-related hearing loss was able to reflect the actual effects of conductive hearing loss on speech perception. DESIGN: Forty-one school-age children with OME-related hearing loss were recruited. Each child with OME was matched with a same sex and age counterpart with normal hearing to make a participant pair. Pure-tone threshold differences at octave frequencies from 125 to 8000 Hz for every participant pair were used as the simulation attenuation levels for the normal-hearing children. Another group of 41 school-age otologically normal children were recruited as a control group without actual or simulated hearing loss. The Mandarin Hearing in Noise Test was utilized, and sentence recall accuracy at four signal to noise ratios (SNR) considered representative of classroom-listening conditions were derived, as well as reception thresholds for sentences (RTS) in quiet and in noise using adaptive protocols. RESULTS: The speech perception in quiet and in noise of children with simulated OME-related hearing loss was significantly poorer than that of otologically normal children. Analysis showed that RTS in quiet of children with OME-related hearing loss and of children with simulated OME-related hearing loss was significantly correlated and comparable. A repeated-measures analysis suggested that sentence recall accuracy obtained at 5-dB SNR, 0-dB SNR, and -5-dB SNR was similar between children with actual and simulated OME-related hearing loss. However, RTS in noise in children with OME was significantly better than that for children with simulated OME-related hearing loss. CONCLUSIONS: The present frequency-specific, attenuation-based simulation method reflected the effects of OME-related hearing loss on speech perception impairment in quiet environments. In noisy environments, the simulation method could only approximately estimate the effects of OME-related hearing loss on speech perception in typical classroom noise levels. Children with OME-related hearing loss may develop compensatory strategies to reduce the effects of hearing loss in adverse listening environments.

Hearing loss in children with otitis media with effusion: a systematic review.

OBJECTIVES: Otitis media with effusion (OME) is the presence of non-purulent inflammation in the middle ear. Hearing impairment is frequently associated with OME. Pure tone audiometry and speech audiometry are two of the most primarily utilised auditory assessments and provide valuable behavioural and functional estimation on hearing loss. This paper was designed to review and analyse the effects of the presence of OME on children's listening abilities. DESIGN: A systematic and descriptive review. STUDY SAMPLE: Twelve articles reporting frequency-specific pure tone thresholds and/or speech perception measures in children with OME were identified using PubMed, Ovid, Web of Science, ProQuest and Google Scholar search platforms. RESULTS: The hearing loss related to OME averages 18-35 dB HL. The air conduction configuration is roughly flat with a slight elevation at 2000 Hz and a nadir at 8000 Hz. Both speech-in-quiet and speech-in-noise perception have been found to be impaired. CONCLUSIONS: OME imposes a series of disadvantages on hearing sensitivity and speech perception in children. Further studies investigating the full range of frequency-specific pure tone thresholds, and that adopt standardised speech test materials are advocated to evaluate hearing related disabilities with greater comprehensiveness, comparability and enhanced consideration of their real life implications.

Psychometric properties of the hearing handicap questionnaire: a Kannada (South-Indian) translation.

OBJECTIVE: To assess the psychometric properties of the Hearing Handicap Questionnaire (HHQ) in Kannada (a South-Indian language) among adults with hearing loss. DESIGN: The study involved a cross-sectional survey design. Participants provided demographic details and completed the Kannada and English (original) version of the HHQ questionnaire. To evaluate test-retest reliability, ∼50% of the participants completed the Kannada version for the second time after 15 days. STUDY SAMPLE: The sample comprised 103 adults with hearing loss recruited from local audiology clinics. RESULTS: Exploratory factor analysis indicated a one-factor structure, which explained 71% of the variance in Kannada-HHQ scores. The internal consistency measured with Cronbach's alpha was 0.96. The test-retest reliability correlations of the Kannada version with the English and with the same Kannada version re-administered after 15 days were 0.96 and 0.91, respectively. Convergent validity of the scale was confirmed by significant correlations with the Participation Scale and the Assessment of Quality of Life scales. Discriminant validity was found to be low as all the Kannada-HHQ questions were highly correlated with each other (r> 0.60). No floor and ceiling effects were identified. CONCLUSIONS: The psychometric properties of the Kannada-HHQ scale are considered to be adequate for clinical or research use.

Classroom Listening Conditions in Indian Primary Schools: A Survey of Four Schools.

INTRODUCTION: Background noise affects the listening environment inside classrooms, especially for younger children. High background noise level adversely affects not only student speech perception but also teacher vocal hygiene. The current study aimed to give an overview of the classroom listening conditions in selected government primary schools in India. MATERIALS AND METHODS: Noise measurements were taken in 23 classrooms of four government primary schools in southern India, using a type 2 sound level meter. In each classroom measurements were taken in occupied and unoccupied conditions. Teacher voice level was measured in the same classrooms. In addition, the classroom acoustical conditions were observed and the reverberation time for each classroom was calculated. RESULTS: The mean occupied noise level was 62.1 dBA and 65.6 dBC, and the mean unoccupied level was 62.2 dBA and 65 dBC. The mean unamplified teacher speech-to-noise ratio was 10.6 dBA. Both the occupied and unoccupied noise levels exceeded national and international recommended levels and the teacher speech-to-noise ratio was also found to be inadequate in most classrooms. The estimated reverberation time in all classrooms was greater than 2.6 seconds, which is almost double the duration of accepted standards. In addition, observation of classrooms revealed insufficient acoustical treatment to effectively reduce internal and external noise and minimize reverberation. CONCLUSION: The results of this study point out the need to improve the listening environment for children in government primary schools in India.

Behavioral Signs of (Central) Auditory Processing Disorder in Children With Nonsyndromic Cleft Lip and/or Palate: A Parental Questionnaire Approach.

Objective Children with nonsyndromic cleft lip and/or palate often have a high prevalence of middle ear dysfunction. However, there are also indications that they may have a higher prevalence of (central) auditory processing disorder. This study used Fisher's Auditory Problems Checklist for caregivers to determine whether children with nonsyndromic cleft lip and/or palate have potentially more auditory processing difficulties compared with craniofacially normal children. Methods Caregivers of 147 school-aged children with nonsyndromic cleft lip and/or palate were recruited for the study. This group was divided into three subgroups: cleft lip, cleft palate, and cleft lip and palate. Caregivers of 60 craniofacially normal children were recruited as a control group. Hearing health tests were conducted to evaluate peripheral hearing. Caregivers of children who passed this assessment battery completed Fisher's Auditory Problems Checklist, which contains 25 questions related to behaviors linked to (central) auditory processing disorder. Results Children with cleft palate showed the lowest scores on the Fisher's Auditory Problems Checklist questionnaire, consistent with a higher index of suspicion for (central) auditory processing disorder. There was a significant difference in the manifestation of (central) auditory processing disorder-linked behaviors between the cleft palate and the control groups. The most common behaviors reported in the nonsyndromic cleft lip and/or palate group were short attention span and reduced learning motivation, along with hearing difficulties in noise. Conclusion A higher occurrence of (central) auditory processing disorder-linked behaviors were found in children with nonsyndromic cleft lip and/or palate, particularly cleft palate. Auditory processing abilities should not be ignored in children with nonsyndromic cleft lip and/or palate, and it is necessary to consider assessment tests for (central) auditory processing disorder when an auditory diagnosis is made for this population.

Chronic exposure to broadband noise at moderate sound pressure levels spatially shifts tone-evoked responses in the rat auditory midbrain.

Noise-induced hearing disorders are a significant public health concern. One cause of such disorders is exposure to high sound pressure levels (SPLs) above 85 dBA for eight hours/day. High SPL exposures occur in occupational and recreational settings and affect a substantial proportion of the population. However, an even larger proportion is exposed to more moderate SPLs for longer durations. Therefore, there is significant need to better understand the impact of chronic, moderate SPL exposures on auditory processing, especially in the absence of hearing loss. In this study, we applied functional magnetic resonance imaging (fMRI) with tonal acoustic stimulation on an established broadband rat exposure model (65 dB SPL, 30 kHz low-pass, 60 days). The auditory midbrain response of exposed subjects to 7 kHz stimulation (within exposure bandwidth) shifts dorsolaterally to regions that typically respond to lower stimulation frequencies. This shift is quantified by a region of interest analysis that shows that fMRI signals are higher in the dorsolateral midbrain of exposed subjects and in the ventromedial midbrain of control subjects (p<0.05). Also, the center of the responsive region in exposed subjects shifts dorsally relative to that of controls (p<0.05). A similar statistically significant shift (p<0.01) is observed using 40 kHz stimulation (above exposure bandwidth). The results suggest that high frequency midbrain regions above the exposure bandwidth spatially expand due to exposure. This expansion shifts lower frequency regions dorsolaterally. Similar observations have previously been made in the rat auditory cortex. Therefore, moderate SPL exposures affect auditory processing at multiple levels, from the auditory cortex to the midbrain.

Long-term, passive exposure to non-traumatic acoustic noise induces neural adaptation in the adult rat medial geniculate body and auditory cortex.

Exposure to loud sounds can lead to permanent hearing loss, i.e., the elevation of hearing thresholds. Exposure at more moderate sound pressure levels (SPLs) (non-traumatic and within occupational limits) may not elevate thresholds, but could in the long-term be detrimental to speech intelligibility by altering its spectrotemporal representation in the central auditory system. In support of this, electrophysiological and behavioral changes following long-term, passive (no conditioned learning) exposure at moderate SPLs have recently been observed in adult animals. To assess the potential effects of moderately loud noise on the entire auditory brain, we employed functional magnetic resonance imaging (fMRI) to study noise-exposed adult rats. We find that passive, pulsed broadband noise exposure for two months at 65 dB SPL leads to a decrease of the sound-evoked blood oxygenation level-dependent fMRI signal in the thalamic medial geniculate body (MGB) and in the auditory cortex (AC). This points to the thalamo-cortex as the site of the neural adaptation to the moderately noisy environment. The signal reduction is statistically significant during 10 Hz pulsed acoustic stimulation (MGB: p<0.05, AC: p<10(-4)), but not during 5 Hz stimulation. This indicates that noise exposure has a greater effect on the processing of higher pulse rate sounds. This study has enhanced our understanding of functional changes following exposure by mapping changes across the entire auditory brain. These findings have important implications for speech processing, which depends on accurate processing of sounds with a wide spectrum of pulse rates.

Adaptive tests of temporal resolution: comparison with the gaps-in-noise test in normal-hearing young adults.

OBJECTIVE: Auditory processing disorder patients may have deficits in auditory temporal resolution. This study explored: (1) the ear specific norms for young adults using the adaptive tests of temporal resolution (ATTR); (2) the reliability of ATTR using two different modes of stimuli presentation; and (3) the concurrent validity of ATTR with reference to the gaps-in-noise (GIN) test. DESIGN: GIN and ATTR were administered through a standard audiometer and headphones. As ATTR can also be completed using a computer with commercially available headphones, thresholds from these two variants were compared. STUDY SAMPLE: Thirty normal-hearing young adults were recruited. RESULTS: The mean ATTR gap detection thresholds (GDTs) derived under audiometer administration were 4.60 ms (SD 1.49) and 4.97 ms (SD 1.98) for the left and right ear, respectively. The approximated threshold (A. th.), an equivalent measure to the GDT in the GIN, mean values were 5.37 ms (SD 0.98) and 5.33 ms (SD 1.07) for left and right ears, respectively. No significant threshold difference was found between the ATTR variants. A positive, moderate correlation was found, and Bland-Altman plot analysis revealed good agreement, between GDT and A.th. CONCLUSIONS: ATTR and GIN results were moderately associated. Moreover, the ATTR was found to have high test-retest reliability and high specificity for the current participants.

Noise levels in an urban Asian school environment.

Background noise is known to adversely affect speech perception and speech recognition. High levels of background noise in school classrooms may affect student learning, especially for those pupils who are learning in a second language. The current study aimed to determine the noise level and teacher speech-to-noise ratio (SNR) in Hong Kong classrooms. Noise level was measured in 146 occupied classrooms in 37 schools, including kindergartens, primary schools, secondary schools and special schools, in Hong Kong. The mean noise levels in occupied kindergarten, primary school, secondary school and special school classrooms all exceeded recommended maximum noise levels, and noise reduction measures were seldom used in classrooms. The measured SNRs were not optimal and could have adverse implications for student learning and teachers' vocal health. Schools in urban Asian environments are advised to consider noise reduction measures in classrooms to better comply with recommended maximum noise levels for classrooms.

Service delivery approaches related to hearing aids in low- and middle-income countries or resource-limited settings: A systematic scoping review.

Hearing loss is an important global public health issue which can be alleviated through treatment with hearing aids. However, most people who would benefit from hearing aids do not receive them, in part due to challenges in accessing hearing aids and related services, which are most salient in low- and middle-income countries (LMIC) and other resource-limited settings. Innovative approaches for hearing aid service delivery can overcome many of the challenges related to access, including that of limited human resources trained to provide ear and hearing care. The purpose of this systematic scoping review is to synthesize evidence on service delivery approaches for hearing aid provision in LMIC and resource-limited settings. We searched 3 databases (PubMed, Scopus, Ovid MEDLINE) for peer-reviewed articles from 2000 to 2022 that focused on service delivery approaches related to hearing aids in LMIC or resource-limited settings. Fifteen peer-reviewed articles were included, which described hospital-based (3 studies), large-scale donation program (1 studies), community-based (7 studies), and remote (telehealth; 4 studies) service delivery approaches. Key findings are that hearing aid services can be successfully delivered in hospital- and community-based settings, and remotely, and that both qualified hearing care providers and trained non-specialists can provide quality hearing aid services. Service delivery approaches focused on community-based and remote care, and task sharing among qualified hearing care providers and trained non-specialists can likely improve access to hearing aids worldwide, thereby reducing the burden of untreated hearing loss.

Xylene-induced auditory dysfunction in humans.

OBJECTIVES: Animal data indicate that xylene induces cochlear dysfunction, characterized by the loss of outer hair cells. There is little evidence regarding xylene-induced ototoxicity in humans. The aim of the study was to investigate the possible adverse effects of xylene on the peripheral and central auditory system in humans. DESIGN: A total of 30 medical laboratory workers who had been exposed to a mixture of xylene isomers, together with 30 nonexposed control participants matched for gender, age, and educational level were selected. Participants of both groups were not exposed to noise levels above 85 dBA time-weighted average. All participants were evaluated with a comprehensive audiological test battery, which included measures of peripheral and central auditory function. Peripheral auditory measures included pure-tone audiometry and distortion product otoacoustic emissions. Behavioral measures of central auditory function included a pitch pattern sequence test, an adaptive test of temporal resolution, a dichotic digit test, and a masking level difference test. The auditory brainstem response was used to objectively evaluate the function of the auditory pathways at the brainstem level. Speech perception in quiet and in noise was evaluated using the Hearing In Noise Test (HINT). The xylene-exposed participants were extensively evaluated with regard to their exposure to both noise and xylene. Noise dosimetry was conducted over an 8-hr work shift to obtain noise-exposure levels for each xylene-exposed worker. Airborne xylene concentrations were obtained at 11 different workstations throughout the medical laboratories, and methyl hippuric acid levels per gram of creatinine in urine were obtained for each xylene-exposed subject. Finally, a detailed interview exploring current and past solvent and noise exposure was conducted. RESULTS: The xylene-exposed participants showed significantly worse pure-tone thresholds in comparison with the nonexposed participants. The xylene-exposed participants demonstrated significantly worse results than the control group participants for the pitch pattern sequence test, dichotic digit test, HINT, and the auditory brainstem response (absolute and interpeak latencies). No significant differences between the xylene-exposed and nonexposed participants were observed for distortion product otoacoustic emissions, adaptive test of temporal resolution, or the masking level difference test. A significant correlation between the concentrations of methyl hippuric acid in urine and pure-tone thresholds (2 to 8 kHz) was found in xylene-exposed workers. Also, participants with high cumulative dose of xylene exposure presented with poorer test results than participants with low cumulative dose of xylene exposure. CONCLUSIONS: The results of the present research suggest that xylene is associated with adverse central auditory effects and poorer sound detection abilities in humans. A major limitation of the study is that the results found among xylene-exposed participants cannot be proved to be permanent, and thus further research should be conducted to clarify this limitation. Workers exposed to this chemical should be routinely evaluated with a comprehensive audiological test battery, to detect early signs of auditory dysfunction.

Auditory dysfunction associated with solvent exposure.

BACKGROUND: A number of studies have demonstrated that solvents may induce auditory dysfunction. However, there is still little knowledge regarding the main signs and symptoms of solvent-induced hearing loss (SIHL). The aim of this research was to investigate the association between solvent exposure and adverse effects on peripheral and central auditory functioning with a comprehensive audiological test battery. METHODS: Seventy-two solvent-exposed workers and 72 non-exposed workers were selected to participate in the study. The test battery comprised pure-tone audiometry (PTA), transient evoked otoacoustic emissions (TEOAE), Random Gap Detection (RGD) and Hearing-in-Noise test (HINT). RESULTS: Solvent-exposed subjects presented with poorer mean test results than non-exposed subjects. A bivariate and multivariate linear regression model analysis was performed. One model for each auditory outcome (PTA, TEOAE, RGD and HINT) was independently constructed. For all of the models solvent exposure was significantly associated with the auditory outcome. Age also appeared significantly associated with some auditory outcomes. CONCLUSIONS: This study provides further evidence of the possible adverse effect of solvents on the peripheral and central auditory functioning. A discussion of these effects and the utility of selected hearing tests to assess SIHL is addressed.

Hearing screening for school children: utility of noise-cancelling headphones.

BACKGROUND: Excessive ambient noise in school settings is a major concern for school hearing screening as it typically masks pure tone test stimuli (particularly 500 Hz and below). This results in false positive findings and subsequent unnecessary follow-up. With advances in technology, noise-cancelling headphones have been developed that reduce low frequency noise by superimposing an anti-phase signal onto the primary noise. This research study examined the utility of noise-cancelling headphone technology in a school hearing screening environment. METHODS: The present study compared the audiometric screening results obtained from two air-conduction transducers-Sennheiser PXC450 noise-cancelling circumaural headphones (NC headphones) and conventional TDH-39 supra-aural earphones. Pure-tone hearing screening results (500 Hz to 4000 Hz, at 30 dB HL and 25 dB HL) were obtained from 232 school children, aged 6 to 8 years, in four Hong Kong primary schools. RESULTS: Screening outcomes revealed significant differences in referral rates between TDH-39 earphones and NC headphones for both 30 dB HL and 25 dB HL criteria, regardless of the inclusion or exclusion of 500 Hz results. The kappa observed agreement (OA) showed that at both screening intensities, the transducers' referral agreement value for the 500 Hz inclusion group was smaller than for the 500 Hz exclusion group. Individual frequency analysis showed that the two transducers screened similarly at 1000 Hz and 2000 Hz at 25 dB HL, as well as at both 30 dB HL and 25 dB HL screening levels for 4000 Hz. Statistically significant differences were found for 500 Hz at 30 dB HL and at 25 dB HL, and for 1000 Hz and 2000 Hz at 30 dB HL. OA for individual frequencies showed weaker intra-frequency agreement between the two transducers at 500 Hz at both intensity criterion levels than at higher frequencies. CONCLUSIONS: NC headphones screening results differed from those obtained from TDH-39 earphones, with lower referral rates at 500 Hz, particularly at the 25 dB HL criterion level. Therefore, NC headphones may be able to operate at lower screening intensities and subsequently increase pure-tone screening test sensitivity, without compromising specificity. NC headphones show some promise as possible replacements for conventional earphones in school hearing screening programs.