Otoacoustic emissions, pure-tone audiometry, and self-reported hearing

The relationship and interdependence of auditory thresholds, proposed behavioural measures of hidden hearing loss, and physiological measures of auditory function

OBJECTIVES

Standard diagnostic measures focus on threshold elevation but hearing concerns may occur independently of threshold elevation - referred to as "hidden hearing loss" (HHL). A deeper understanding of HHL requires measurements that locate dysfunction along the auditory pathway. This study aimed to describe the relationship and interdependence between certain behavioural and physiological measures of auditory function that are thought to be indicative of HHL.

DESIGN

Data were collected on a battery of behavioural and physiological measures of hearing. Threshold-dependent variance was removed from each measure prior to generating a multiple regression model of the behavioural measures using the physiological measures.

STUDY SAMPLE

224 adults in the United States with audiometric thresholds ≤65 dB HL.

RESULTS

Thresholds accounted for between 21 and 60% of the variance in our behavioural measures and 5-51% in our physiological measures of hearing. There was no evidence that the behavioural measures of hearing could be predicted by the selected physiological measures.

CONCLUSIONS

Several proposed behavioural measures for HHL: thresholds-in-noise, frequency-modulation detection, and speech recognition in difficult listening conditions, are influenced by hearing sensitivity and are not predicted by outer hair cell or auditory nerve physiology. Therefore, these measures may not be able to assess threshold-independent hearing disorders.

Wideband Tympanometry and Pressurized Otoacoustic Emissions in Children with Surgical Excision of Palatine and/or Pharyngeal Tonsils

Palatine and pharyngeal tonsil hypertrophy may lead to dysfunction of the auditory tube due to a propensity for infection, potentially giving rise to otitis media. This is a quantitative and longitudinal study, developed from 2019 to 2021, at the State University of Campinas (UNICAMP). The studied sample comprised 15 participants aged 5 to 12 years (mean 7.9 years), 12 male and 3 female, arranged into two groups: children diagnosed with pharyngeal and/or palatine tonsil hypertrophy who were candidates for surgery (G1), and children who were later evaluated after surgery (G2). As part of the test, an otoscopy and measurements of logoaudiometry, pure-tone threshold audiometry, wideband tympanometry (ambient and peak pressure), and otoacoustic emissions (TEOAEs and DPOAEs, both at ambient and peak pressure) were all performed. There were statistically significant differences between phases in pure-tone audiometry, in terms of 226 Hz tympanometry, wideband tympanometry in peak pressure conditions, in the amplitude measurement TEOAEs in both pressure conditions, in DPOAEs in ambient pressure conditions, and in the signal/noise measurement in both pressures in DPOAEs. Overall, it was found that hearing tests were different for subjects with palatine and pharyngeal tonsil hypertrophy compared to the post-surgical group.

The Benefit of Air Conduction Pure-Tone Audiometry as a Screening Method for Hearing Loss over the VAS Score

Hearing loss is commonly encountered by general practitioners. We aimed to evaluate the screening benefit of air conduction pure-tone audiometry over visual analogue scale (VAS) scores for hearing loss. Moreover, we intended to perform the first cross-sectional study in Greece to assess hearing loss with pure-tone audiometry in young adults of the general population. We evaluated Greeks between 15 and 40 years old in a high school in Karditsa, Greece, and a primary health care unit in a nearby community. Subjects filled out a VAS score sheet and underwent pure-tone audiometry in a room without sound isolation, with air conduction only. We named the latter procedure modified pure-tone audiometry (mPTA). Subjects with pathologic results were examined via otoscopy and standardized pure-tone audiometry (sPTA). Of the 286 subjects evaluated, the VAS score revealed 5 subjects (1.7%) with hearing loss. mPTA (100 s duration) doubled this percentage (in total 3.8%; Pearson Chi-Square test; p < 0.001). Based on sPTA, the sensitivity and positive predictive value of the VAS score were 40% and 13%, respectively. For mPTA, they were 100% and 37%, respectively. mPTA filtered out pathologic cases in a proper, rapid, cheap and simple way and may be considered a proper screening method for hearing loss in primary health care.

Testing the reliability and validity of the modified Amsterdam Inventory for Auditory Disability and Handicap in career firefighters in the United States

BACKGROUND

Firefighters are routinely exposed to loud noise that put them at risk for hearing loss. A reliable and valid measure to assess firefighters' hearing function is important. This study aims to test the reliability and validity of the modified Amsterdam Inventory for Auditory Disability and Handicap ((m)AIADH) in firefighters.

METHOD

A cross-sectional study was conducted using a convenience sample of 239 career firefighters from six partnered fire departments in Central Texas and Northern California. The internal consistency, convergent and criterion validity, and the ability to discriminate groups by measured hearing, perceived hearing, and a combination of measured and perceived hearing, were examined using the total score and score for each of the five subscales of the (m)AIADH.

RESULTS

The study participants were primarily men (93%). Satisfactory internal consistency was revealed for the (m)AIADH with Cronbach's alpha above 0.80 for all five subscales. Criterion analysis presented a moderate correlation between the (m)AIADH and the average of hearing threshold at high frequencies (4, 6, and 8 kHz). For convergent validity, the (m)AIADH was moderately to highly related with perceived hearing. There were statistically significant differences in the total (m)AIADH score and the five subscales for measured hearing thresholds except for "intelligibility in quiet." The (m)AIADH also showed a discriminative ability to distinguish between the group with good perceived hearing and the group with bad perceived hearing.

CONCLUSION

The (m)AIADH is a reliable and valid measure to assess various dimensions of hearing function among firefighters.

Listening-Based Communication Ability in Adults With Hearing Loss: A Scoping Review of Existing Measures

Introduction

Hearing loss in adults has a pervasive impact on health and well-being. Its effects on everyday listening and communication can directly influence participation across multiple spheres of life. These impacts, however, remain poorly assessed within clinical settings. Whilst various tests and questionnaires that measure listening and communication abilities are available, there is a lack of consensus about which measures assess the factors that are most relevant to optimising auditory rehabilitation. This study aimed to map current measures used in published studies to evaluate listening skills needed for oral communication in adults with hearing loss.

Methods

A scoping review was conducted using systematic searches in Medline, EMBASE, Web of Science and Google Scholar to retrieve peer-reviewed articles that used one or more linguistic-based measure necessary to oral communication in adults with hearing loss. The range of measures identified and their frequency where charted in relation to auditory hierarchies, linguistic domains, health status domains, and associated neuropsychological and cognitive domains.

Results

9121 articles were identified and 2579 articles that reported on 6714 discrete measures were included for further analysis. The predominant linguistic-based measure reported was word or sentence identification in quiet (65.9%). In contrast, discourse-based measures were used in 2.7% of the articles included. Of the included studies, 36.6% used a self-reported instrument purporting to measures of listening for communication. Consistent with previous studies, a large number of self-reported measures were identified (n = 139), but 60.4% of these measures were used in only one study and 80.7% were cited five times or fewer.

Discussion

Current measures used in published studies to assess listening abilities relevant to oral communication target a narrow set of domains. Concepts of communicative interaction have limited representation in current measurement. The lack of measurement consensus and heterogeneity amongst the assessments limit comparisons across studies. Furthermore, extracted measures rarely consider the broader linguistic, cognitive and interactive elements of communication. Consequently, existing measures may have limited clinical application if assessing the listening-related skills required for communication in daily life, as experienced by adults with hearing loss.

Occupational noise exposure and asymmetric hearing loss: Results from the HUNT population study in Norway

BACKGROUND

A large population study with adequate data on confounders is required to determine whether asymmetric hearing loss (AHL) is associated with occupational noise exposure.

METHODS

We performed a cross-sectional population study in Norway (the Health Investigation in Nord-Trøndelag: HUNT) with 24 183 participants, using pure-tone audiometry and questionnaires. AHL was defined as a difference in hearing threshold between the right and left ears of greater than or equal to 15 dB for the pure-tone average of 0.5 to 2 or 3 to 6 kHz.

RESULTS

The mean age of the participants was 53 years (range, 19-99); 53% were women. The prevalence of AHL in this general Norwegian population was 6% for the 0.5 to 2 kHz range and 15% for 3 to 6 kHz. In unadjusted regression models, subjects reporting prolonged occupational noise exposure to high-level noise sources (N = 1652) had a higher risk of AHL at 3 to 6 kHz than those reporting no prior exposure (odds ratio [OR], 1.98; 95% confidence interval [CI], 1.75-2.25). After adjustment for age and sex, OR was 1.08; (95% CI, 0.95-1.24). After additional adjustment for head trauma, ear infections, blasting or shooting (all associated with AHL), smoking, and diabetes, OR was 1.00 (95% CI, 0.87-1.16). No association between occupational noise and right-ear hearing threshold advantage (left-right ear difference) was observed after adjustment for confounders.

CONCLUSION

Our study suggests that AHL is relatively common in the general population, especially at the high-frequency range in men and elderly subjects. Our study showed no relation between occupational noise exposure and AHL after confounder adjustment.

Otoacoustic emissions in patients with bacterial meningitis

Objective: Systematic evaluation of studies using otoacoustic emissions (OAEs) to monitor cochlear damage in patients with bacterial meningitis.Design: Systematic review. This includes articles retrieved from PUBMED and EMBASE. The search-strategy was based on the PICO-model. Data processing involved Cochrane Public Health Data Extraction template in addition to assessment of risk of bias and applicability with the Second Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool.Study samples: Thirty-eight articles were identified with 6 studies comprising 391 children and 17 adult patients eligible for full assessment.Results: Studies were heterogenic and the timing of OAE was incomparable between studies. The frequency of severe loss of hearing was reported to occur between 1.6 and 21% of the patients with culture-proven meningitis. The included studies, albeit heterogenic, found OAE-screening feasible and sensitive in children recovering from bacterial meningitis.Conclusion: No children with hearing loss were reported to pass an OAE screening in any of the included studies. The timing, sensitivity and extent of sensorineural hearing loss determined by OAE could not be assessed from the included studies. Levels of risk of bias were inconsistent and the clinical feasibility for routine inclusion of patients with bacterial meningitis was uncertain. The technological development within this field implies the need for further research.

Auditory function and prevalence of specific ear and hearing related pathologies in the general population at age 70

Objective: To describe the auditory function in early old age in detail based on both psychoacoustic and physiological measures, and to investigate the prevalence of specific audiological and otological pathologies.Design: An unscreened subsample from a population-based geriatric investigation was examined with otoscopy; tympanometry; pure-tone audiometry; word-recognition-in-noise test; distortion-product otoacoustic emissions; and auditory-evoked brainstem responses. Audiometric subtypes and diagnoses were established based on set criteria. The association between word scores and ABR was examined with linear regression analysis.Study Sample: 251 persons aged 70 (113 men, 138 women, born in 1944) that were representative of the inhabitants of the city of Gothenburg.Results: The prevalence of conductive pathology was 2% versus 49% for cochlear and 2% for auditory-neural pathology. Four percent had indeterminate type. Cochlear dysfunction was present in the majority of ears and around 20% performed worse-than-expected on speech testing. Poor performance on the speech in noise test was associated with prolonged interpeak latency interval of ABR waves I-V.Conclusion: Specific otological and audiological pathologies, other than cochlear hearing loss, are rare in the general population at age 70. Additionally, there is subtle evidence of age-related decline of the auditory nerve. Longitudinal follow-up would be of great interest.

Hearing Disability Prevalence and Risk Factors in Two Recent National Surveys

INTRODUCTION

Hearing loss is a worldwide societal and public health concern. Globally, disabling hearing loss affects 538 million adults (men, 12.2%; women, 9.8%). This study examined the prevalence and risk factors associated with deafness or serious difficulty hearing in two nationally representative surveys.

METHODS

Data were analyzed in 2017 from the 2016 Behavioral Risk Factor Surveillance System (BRFSS) and the 2014 National Health Interview Survey. The BRFSS collected data through telephone interviews. The 2014 National Health Interview Survey collected face-to-face household interview data that included a hearing health supplement in the Sample Adult Core. Both surveys asked adults aged ≥18 years the disability question on deafness or serious difficulty hearing as defined by the American Community Survey. Weighted prevalence, prevalence ratios, and 95% CIs were calculated. Logistic regression was used to adjust for sociodemographic and geographic characteristics.

RESULTS

Prevalence of deafness or serious difficulty hearing was 5.8% (BRFSS) and 6.0% (National Health Interview Survey); males had a 60% higher prevalence than females. The prevalence was significantly associated with increasing age, lower educational level and income, and was higher among non-Hispanic whites than among non-Hispanic blacks and Hispanics. Deafness or serious difficulty hearing was strongly associated with increasing degree of self-reported trouble hearing in the National Health Interview Survey. The BRFSS state-specific prevalence varied from 3.8% to 13.3%, with higher prevalence in the most public health-challenged states according to America's Health Rankings.

CONCLUSIONS

The prevalence of deafness or serious difficulty hearing was approximately 6% in the National Health Interview Survey and BRFSS, but increased considerably for older, less advantaged individuals and in more public health-challenged states.

Readability of Patient-Reported Outcome Measures in Adult Audiologic Rehabilitation

PURPOSE

The purpose of this study was to examine the readability of published patient-reported outcome measures (PROMs) designed for use in adult audiologic rehabilitation. The readability results were compared with the readability levels recommended for health information by health literacy experts.

METHOD

Reading grade levels were calculated using the Flesch-Kincaid Grade Level Formula (Flesch, 1948), Gunning Fog Index (Gunning, 1952), Simple Measure of Gobbledygook (McLaughlin, 1969), and FORCAST (Caylor, Sticht, Fox, & Ford, 1973) readability formulas for 10 published PROMs. Descriptive statistics were computed across the different PROM sections: instructions, items, response scale, and overall contents of the measure directed toward respondents.

RESULTS

The majority of the PROM sections exceeded the 6th grade reading level recommended by health literacy experts, regardless of the formula applied. All PROM sections exceeded the 6th grade reading level when calculated according to the FORCAST formula, the most appropriate readability formula for use with a nonnarrative text format, such as PROMs.

CONCLUSIONS

When developing or reevaluating PROMs designed for use in adult audiologic rehabilitation, researchers should consider ways to improve the readability of their measure, as poor readability may affect the validity of the empirical data collected using the PROM. Additionally, the adequate readability of audiologic PROMs is required if patient/family-centered care values are to be adhered to within the field of adult audiologic rehabilitation.

On the Etiology of Listening Difficulties in Noise Despite Clinically Normal Audiograms

Many people with difficulties following conversations in noisy settings have “clinically normal” audiograms, that is, tone thresholds better than 20 dB HL from 0.1 to 8 kHz. This review summarizes the possible causes of such difficulties, and examines established as well as promising new psychoacoustic and electrophysiologic approaches to differentiate between them. Deficits at the level of the auditory periphery are possible even if thresholds remain around 0 dB HL, and become probable when they reach 10 to 20 dB HL. Extending the audiogram beyond 8 kHz can identify early signs of noise-induced trauma to the vulnerable basal turn of the cochlea, and might point to “hidden” losses at lower frequencies that could compromise speech reception in noise. Listening difficulties can also be a consequence of impaired central auditory processing, resulting from lesions affecting the auditory brainstem or cortex, or from abnormal patterns of sound input during developmental sensitive periods and even in adulthood. Such auditory processing disorders should be distinguished from (cognitive) linguistic deficits, and from problems with attention or working memory that may not be specific to the auditory modality. Improved diagnosis of the causes of listening difficulties in noise should lead to better treatment outcomes, by optimizing auditory training procedures to the specific deficits of individual patients, for example.

Hearing loss, lead (Pb) exposure, and noise: a sound approach to ototoxicity exploration

To determine the state of the research on ototoxic properties of Pb, evaluate possible synergistic effects with concurrent noise exposure, and identify opportunities to improve future research, we performed a review of the peer-reviewed literature to identify studies examining auditory damage due to Pb over the past 50 years. Thirty-eight studies (14 animal and 24 human) were reviewed. Of these, 24 suggested potential ototoxicity due to Pb exposure, while 14 found no evidence of ototoxicity. More animal studies are needed, especially those investigating Pb exposure levels that are occupationally and environmentally relevant to humans. Further investigations into potential interactions of Pb in the auditory system with other hazards and compounds that elicit ototoxicity are also needed in animal models. To better assess the effects of Pb exposure on the human auditory system and the possibility of a synergism with noise, future epidemiological studies need to carefully consider and address four main areas of uncertainty: (1) hearing examination and quantification of hearing loss, (2) Pb exposure evaluation, (3) noise exposure evaluation, and (4) the personal characteristics of those exposed. Two potentially confounding factors, protective factors and mixtures of ototoxicants, also warrant further exploration.

Validating self-reporting of hearing-related symptoms against pure-tone audiometry, otoacoustic emission, and speech audiometry

OBJECTIVE

To validate self-reported hearing-related symptoms among personnel exposed to moderately high occupational noise levels at an obstetrics clinic.

DESIGN

Sensitivity, specificity, and predictive values were calculated for questionnaire items assessing hearing loss, tinnitus, sound sensitivity, poor hearing, difficulty perceiving speech, and sound-induced auditory fatigue. Hearing disorder was diagnosed by pure-tone audiometry, distortion product otoacoustic emissions, and HINT (Hearing In Noise Test).

STUDY SAMPLE

Fifty-five female obstetrics personnel aged 22-63 participated; including 26 subjects reporting hearing loss, poor hearing, tinnitus, or sound sensitivity, and 29 randomly selected subjects who did not report these symptoms.

RESULTS

The questionnaire item assessing sound-induced auditory fatigue had the best combination of sensitivity ≥85% (95% CIs 56 to 100%) and specificity ≥70% (95% CIs 55 to 84%) for hearing disorder diagnosed by audiometry or otoacoustic emission. Of those reporting sound-induced auditory fatigue 71% were predicted to have disorder diagnosed by otoacoustic emission. Participants reporting any hearing-related symptom had slightly worse measured hearing.

CONCLUSIONS

We suggest including sound-induced auditory fatigue in questionnaires for identification of hearing disorder among healthcare personnel, though larger studies are warranted for precise estimates of diagnostic performance. Also, more specific and accurate hearing tests are needed to diagnose mild hearing disorder.

No Association Between Time of Onset of Hearing Loss (Childhood Versus Adulthood) and Self-Reported Hearing Handicap in Adults

PURPOSE

This study examined the association between time of onset of hearing loss (childhood vs. adulthood) and self-reported hearing handicap in adults.

METHODS

This is a population-based cohort study of 2,024 adults (mean = 48 years) with hearing loss (binaural pure-tone average 0.5-4 kHz ≥ 20 dB HL) who completed a hearing handicap questionnaire. In childhood, the same persons (N = 2,024) underwent audiometry in a school investigation (at ages 7, 10, and 13 years), in which 129 were diagnosed with sensorineural hearing loss (binaural pure-tone average 0.5-4 kHz ≥ 20 dB HL), whereas 1,895 had normal hearing thresholds.

RESULTS

Hearing handicap was measured in adulthood as the sum-score of various speech perception and social impairment items (15 items). The sum-score increased with adult hearing threshold level (p < .001). After adjustment for adult hearing threshold level, hearing aid use, adult age, sex, and socioeconomic status, there was no significant difference in hearing handicap sum-score between the group with childhood-onset hearing loss (n = 129) and the group with adult-onset hearing loss (n = 1,895; p = .882).

CONCLUSION

Self-reported hearing handicap in adults increased with hearing threshold level. After adjustment for adult hearing threshold level, this cohort study revealed no significant association between time of onset of hearing loss (childhood vs. adulthood) and self-reported hearing handicap.

Severe malaria in children leads to a significant impairment of transitory otoacoustic emissions--a prospective multicenter cohort study

BACKGROUND

Severe malaria may influence inner ear function, although this possibility has not been examined prospectively. In a retrospective analysis, hearing impairment was found in 9 of 23 patients with cerebral malaria. An objective method to quickly evaluate the function of the inner ear are the otoacoustic emissions. Negative transient otoacoustic emissions are associated with a threshold shift of 20 dB and above.

METHODS

This prospective multicenter study analyses otoacoustic emissions in patients with severe malaria up to the age of 10 years. In three study sites (Ghana, Gabon, Kenya) 144 patients with severe malaria and 108 control children were included. All malaria patients were treated with parental artesunate.

RESULTS

In the control group, 92.6 % (n = 108, 95 % confidence interval 86.19-6.2 %) passed otoacoustic emission screening. In malaria patients, 58.5 % (n = 94, malaria vs controls p < 0.001, 95 % confidence interval 48.4-67.9 %) passed otoacoustic emission screening at the baseline measurement. The value increased to 65.2 % (n = 66, p < 0.001, 95 % confidence interval 53.1-75.5 %) at follow up 14-28 days after diagnosis of malaria. The study population was divided into severe non-cerebral malaria and severe malaria with neurological symptoms (cerebral malaria). Whereas otoacoustic emissions in severe malaria improved to a passing percentage of 72.9 % (n = 48, 95 % confidence interval 59-83.4 %) at follow-up, the patients with cerebral malaria showed a drop in the passing percentage to 33 % (n = 18) 3-7 days after diagnosis. This shows a significant impairment in the cerebral malaria group (p = 0.012 at days 3-7, 95 % confidence interval 16.3-56.3 %; p = 0.031 at day 14-28, 95 % confidence interval 24.5-66.3 %).

CONCLUSION

The presented data show that 40 % of children have involvement of the inner ear early in severe malaria. In children, audiological screening after severe malaria infection is not currently recommended, but is worth investigating in larger studies.

Subjective and clinically assessed hearing loss; a cross-sectional register-based study on a swedish population aged 18 through 50 years

OBJECTIVES

Questionnaire studies suggest that hearing is declining among young adults. However, few studies have examined the reliability of hearing questionnaires among young adult subjects. This study examined the associations between pure tone audiometrically assessed (PTA) hearing loss and questionnaire responses in young to middle aged adults.

MATERIALS AND METHODS

A cross-sectional study using questionnaire and screening PTA (500 through 6000 Hz) data from 15322 Swedish subjects (62% women) aged 18 through 50 years. PTA hearing loss was defined as a hearing threshold above 20 dB in both ears at one or more frequencies. Data were analysed with chi-square tests, nonlinear regression, binary logistic regression, and the generalized estimating equation (GEE) approach.

RESULTS

The prevalence of PTA hearing loss was 6.0% in men and 2.9% in women (p < 0.001). Slight hearing impairment was reported by 18.5% of the men and 14.8% of the women (p < 0.001), whereas 0.5% of men and women reported very impaired hearing. Using multivariate GEE modelling, the odds ratio of PTA hearing loss was 30.4 (95% CI, 12.7-72.9) in men and 36.5 (17.2-77.3) in women reporting very impaired hearing. The corresponding figures in those reporting slightly impaired hearing were 7.06 (5.25-9.49) in men and 8.99 (6.38-12.7) in women. These values depended on the sound stimulus frequency (p = 0.001). The area under the ROC curve was 0.904 (0.892-0.915) in men and 0.886 (0.872-0.900) in women.

CONCLUSIONS

Subjective hearing impairment predicted clinically assessed hearing loss, suggesting that there is cause for concern as regards the future development of hearing in young to middle-aged people.

Stimulus and transducer effects on threshold

OBJECTIVE

This study examined differences in thresholds obtained under Sennheiser HDA200 circumaural earphones using pure tone, equivalent rectangular noise bands, and 1/3 octave noise bands relative to thresholds obtained using Telephonics TDH-39P supra-aural earphones.

DESIGN

Thresholds were obtained via each transducer and stimulus condition six times within a 10-day period.

STUDY SAMPLE

Forty-nine adults were selected from a prior study to represent low, moderate, and high threshold reliability.

RESULTS

The results suggested that (1) only small adjustments were needed to reach equivalent TDH-39P thresholds, (2) pure-tone thresholds obtained with HDA200 circumaural earphones had reliability equal to or better than those obtained using TDH-39P earphones, (3) the reliability of noise-band thresholds improved with broader stimulus bandwidth and was either equal to or better than pure-tone thresholds, and (4) frequency-specificity declined with stimulus bandwidths greater than one equivalent rectangular band, which could complicate early detection of hearing changes that occur within a narrow frequency range.

CONCLUSIONS

These data suggest that circumaural earphones such as the HDA200 headphones provide better reliability for audiometric testing as compared to the TDH-39P earphones. These data support the use of noise bands, preferably ERB noises, as stimuli for audiometric monitoring.

Prenatal and postnatal serum PCB concentrations and cochlear function in children at 45 months of age

BACKGROUND

Some experimental and human data suggest that exposure to polychlorinated biphenyls (PCBs) may induce ototoxicity, though results of previous epidemiologic studies are mixed and generally focus on either prenatal or postnatal PCB concentrations exclusively.

OBJECTIVES

Our aim was to evaluate the association between pre- and postnatal PCB concentrations in relation to cochlear status, assessed by distortion product otoacoustic emissions (DPOAEs), and to further clarify the critical periods in development where cochlear status may be most susceptible to PCBs.

METHODS

A total of 351 children from a birth cohort in eastern Slovakia underwent otoacoustic testing at 45 months of age. Maternal pregnancy, cord, and child 6-, 16-, and 45-month blood samples were collected and analyzed for PCB concentrations. At 45 months of age, DPOAEs were assessed at 11 frequencies in both ears. Multivariate, generalized linear models were used to estimate the associations between PCB concentrations at different ages and DPOAEs, adjusting for potential confounders.

RESULTS

Maternal and cord PCB-153 concentrations were not associated with DPOAEs at 45 months. Higher postnatal PCB concentrations at 6-, 16-, and 45-months of age were associated with lower (poorer) DPOAE amplitudes. When all postnatal PCB exposures were considered as an area-under-the-curve metric, an increase in PCB-153 concentration from the 25th to the 75th percentile was associated with a 1.6-dB SPL (sound pressure level) decrease in DPOAE amplitude (95% CI: -2.6, -0.5; p = 0.003).

CONCLUSIONS

In this study, postnatal rather than maternal or cord PCB concentrations were associated with poorer performance on otoacoustic tests at age 45 months.