Hearing Threshold Levels Research Articles

Electrophysiological differences in distinct hearing threshold level individuals with and without tinnitus distress.

Tinnitus is the perception of sound when no actual external noise is present. Tinnitus is highly prevalent, with more than 1 in 7 adults in the EU having tinnitus, and it causes negative effects on quality of life for many individuals. However, there is currently no cure for tinnitus and its pathophysiology and genesis are unknown. Auditory evoked potentials (AEPs) provide a non-invasive means by which the electrical signals evoked by the brain can be recorded, and constitute a useful indicator for the evaluation of auditory disorders such as tinnitus and hearing loss. The present study analyzed a total of 98 auditory middle evoked potential (AMLR) waveforms, a subtype of AEPs, from 49 participants with subjective tinnitus, attempting to identify differences in AMLR parameters between sufferers with and without tinnitus distress. The waveforms were divided into three categories according to the ear's hearing level, and comparisons were made between sufferers in the same hearing level category. The results of the analysis indicated some statistically significant differences in AMLR latencies and amplitudes between the compared groups. Clinical Relevance- Identification of the electro-physiological profile of subjective tinnitus sufferers based on the distress manifested by tinnitus using AMLRs.

The effect of age and hearing sensitivity at frequencies above 8 kHz on auditory stream segregation and speech perception.

The effects of age and mild hearing loss over the extended high-frequency (EHF) range from 9000 to 16 000 Hz on speech perception and auditory stream segregation were assessed using four groups: (1) young with normal hearing threshold levels (HTLs) over both the conventional and EHF range; (2) older with audiograms matched to those for group 1; (3) young with normal HTLs over the conventional frequency range and elevated HTLs over the EHF range; (4) older with audiograms matched to those for group 3. For speech in quiet, speech recognition thresholds and speech identification scores did not differ significantly across groups. For monosyllables in noise, both greater age and hearing loss over the EHF range adversely affected performance, but the effect of age was much larger than the effect of hearing status. Stream segregation was assessed using a rapid sequence of vowel stimuli differing in fundamental frequency (F0). Larger differences in F0 were required for stream segregation for the two groups with impaired hearing in the EHF range, but there was no significant effect of age. It is argued that impaired hearing in the EHF range is associated with impaired auditory function at lower frequencies, despite normal audiometric thresholds at those frequencies.

Application of ISO 1999:2013 (E) model in risk assessment of hearing loss caused by industrial noise

To assess the risk of hearing loss caused by industrial noise exposure of welders and assemblers in a mechanical equipment manufacturing enterprise, and to explore the practical application and possible underestimation of ISO 1999∶2013(E) model. A total of 829 noise-exposed male workers from a mechanical equipment manufacturing enterprise were selected as study subjects. The questionnaire survey was administered, and individual noise exposure level(L_(Aeq.8 h)) and hearing loss level were measured. The risk assessment method of ISO 1999∶2013(E) was used to calculate the change of hearing threshold level and the risk of noise-induced hearing loss. By comparing the median of permanent hearing threshold shift caused by actual noise with the median of ISO1999 predicted value, the reason of the difference between the predicted value of ISO 1999∶2013(E) model and the actual value was analyzed. The L_(Aeq.8 h )was 89.5 dB(A), 77.4%(n=62)of the individual noise exposure levels exceeded 85 dB(A), and 24.6% of the participants(n=829) had different degrees of hearing loss. There was significant difference in hearing loss rate between welding and assembly positions(χ~2=10.07, P<0.01). The risk of noise-induced high-frequency hearing loss of 90% welders was 11.2% at the age of 50, and 14.0% at the age of 60. The risk of noise-induced deafness of 90% welders was 4.3% at the age of 60. The risk of high noise-induced frequency hearing loss of 90% assemblers was at the range of 4.0%-9.0% at the age of 40, 20.8% at the age of 50, and 22.5% at the age of 60. The risk of noise-induced deafness of 90% assemblers was at the range of 1.4%-6.4% at the age of 50, and 9.0% at the age of 60. Compared with actual median of permanent hearing threshold shift, ISO1999∶2013(E) predictions underestimated the median of permanent hearing threshold shift at 10.7 dB. The noise hazards of welding and assembly positions in mechanical equipment manufacturing enterprises are high relatively. ISO1999∶2013(E) can be used to predict the risk of noise-induced hearing loss in workers, but attention should be paid to the risk underestimation of this model.

Reference equivalent threshold sound pressure levels for the Wireless Automated Hearing Test System.

This paper presents reference equivalent threshold sound pressure levels (RETSPLs) for the Wireless Automated Hearing Test System (WAHTS), a recently commercialized device developed for use as a boothless audiometer. Two initial studies were conducted following the ISO 389-9 standard [ISO 389-9 (2009). "Acoustics-Reference zero for the calibration of audiometric equipment. Part 9: Preferred test conditions for the determinations of reference hearing threshold levels" (International Organization for Standardization, Geneva)]. Although the standard recruitment criteria are intended to yield otologically normal test subjects, the recruited populations appeared to have slightly elevated thresholds [5-10 dB hearing level (HL)]. Comparison of WAHTS thresholds to other clinical audiometric equipment revealed bias errors that were consistent with the elevated thresholds of the RETSPL populations. As the objective of RETSPLs is to ensure consistent thresholds regardless of the equipment, this paper presents the RETSPLs initially obtained following ISO 389-9:2009 and suggested correction to account for the elevated HLs of the originally recruited populations. Two additional independent studies demonstrate the validity of these corrected thresholds.

Re-estimated normal hearing threshold levels for pure tones using the calculation procedure of ISO 7029:2017

Objective The objectives of this study were (1) to re-calculate hearing threshold levels (HTLs) for pure tones as described in an international standard, ISO 7029:2017, and (2) to explain the procedure of how HTLs in the standard had been derived. Design Pure-tone hearing threshold data used for developing ISO 7029:2017 and additional data sets were combined to re-estimate median HTLs and the distribution of individual HTLs around the median. The calculation was done for audiometric frequencies from 125 Hz to 8000 Hz and extended high frequencies from 9000 Hz to 12,500 Hz for ages from 18 to 80 years. Study sample Approximately 9000 men and 20,000 women employed in 15 studies in nine countries. They had been rigorously screened for hearing abnormalities. Results A new set of median HTLs and distribution around the median was obtained as a function of age for males and females separately and compared with the estimates in ISO 7029. The differences among these threshold values were discussed. Conclusions The calculation procedure described would help understand how the normative HTLs in ISO 7029:2017 had been obtained. Re-calculated HTLs could serve as a basis for the next edition of the standard that covers a wider range of population.

Correlation of size of tympanic membrane perforation & degree of hearing loss and frequency specific hearing gain following tympanoplasty

Introduction: The tympanic membrane (TM) serves as a key component of the tympano-ossicular system. Chronic otitis media is known to cause mild to moderate conductive hearing loss. Material & Methods: The proposed study was conducted on 50 patients of either sex in age group of 15-50 years having unilateral or bilateral chronic inactive (mucosal) otitis media after obtaining their consent. Pure tone audiogram was done to confirm the degree, type and frequency specific hearing loss from frequency 250Hz to 8000Hz for air conduction and 250Hz to 4000Hz for bone conduction. TM perforations were divided into Group I (small), II (medium), III (Large) according to size of perforation. Results: Average Hearing loss in Group I, II, & III was 33.86, 43.84 & 46.75 dB respectively. Hearing improvement following tympanoplasty at 250, 500, 1000, 2000, 4000, 8000 Hz was 20.50, 18.1, 16.7, 14.3, 12.0, 1.6 dB respectively. Conclusion: Hearing threshold level depends on size of the tympanic membrane perforation. Hearing improvement following tympanoplasty is frequency-dependent also.

Náhle vzniklá percepční nedoslýchavost u dětí: přehled dia­gnostiky, terapie a prognóza

Introduction: Sudden sensorineural hearing loss (SSHL) is an acute condition in children. Universal guidelines for treatment and dia­gnosis are not defined. Use of objective dia­gnostic methods in hearing threshold level verification is necessary. Standardized follow-up care is essential for adequate correction of hearing impairment. Methods and material: This retrospective study analysed 14 patients suffering from SSHL, hospitalized between 2016 and 2019 in a tertiary centre. Age, gender, affected side, hearing threshold level, symptoms, cause and treatment were compared. Hearing loss was classified according to the WHO methodology. The recovery rate was assessed by Siegel’s criteria. Results: All children were treated with an initial dose of 5 mg/kg/day of methylprednisolone intravenously. A complete recovery in our group was achieved in 6 cases (43%). The rate of treatment failure was 75% for the left side and 16.7% for right side SSHL. Patients with the presence of tinnitus have a 54.5% chance of hearing restitution, as compared to 35.3% in patients without tinnitus. The risk of treatment failure for children aged 5–10 years, 10–15 years and 15–18 years is 33%, 83% and 20% respectively. We did not observe any effect on hearing recovery for the other analysed parameters. Conclusions: Better hearing recovery was observed in children with tinnitus, the right affected side and a higher severity of initial hearing loss. At the age of 10–15 years, the chance of hearing recovery was three times lower than in other age groups. Key words sudden sensorineural hearing loss – children – correction of hearing impairment

Does frequency-specific cortical auditory evoked potential accurately reflect the behavioural hearing threshold?

Background: One of the most important and clinically useful aspects of the CAEP is that in adults, the response can be observed close to, and therefore can be used as an objective estimator of the auditory threshold. This has obvious applications in patients that cannot or will not produce reliable responses during pure tone audiometry (PTA). Objectives: to correlate the hearing threshold level measured objectively by N1-P2 CAEP at different tonal frequencies to behavioural hearing threshold level. Methods: Included 77 adult subjects. Hearing threshold was measured behaviourally by PTA then objectively by N1-P2 CAEP. Ears were divided into similar degree of hearing /hearing loss et each frequency in each group to resemble a flat audiogram configuration. Results: There were no statistically significant differences between PTA threshold and N1P2 threshold at the four tested frequencies in the different hearing degrees groups of the study, except for statistically significant lower N1P2 threshold than PTA threshold in the profound hearing loss group at 1000 and 2000 Hz. And in each of the moderate, moderately severe, Severe and profound hearing loss groups at 4000 Hz.

Early audiological phenotype in patients with mutations in the USH2A gene

IntroductionNowadays, due to universal newborn hearing screening (UNHS) the number of children with mild-to-moderate hearing loss diagnosed in the first year of life has increased significantly. Aside from that, identification of the genetic cause improves the genetic counselling of the families and allows to reveal possible comorbidities which may need a special approach. ObjectiveTo present the characteristics of the early audiologic phenotype in hearing impaired patients with biallelic mutations in the USH2A gene based on systematic analysis of the audiological data. Patients and methods13 patients with mutations in the USH2A gene underwent audiological examination. Most of them were found among a large group of infants with bilateral nonsyndromic sensorineural hearing loss (SNHL) examined under 12 months. ResultsEight out of eleven children failed UNHS and were initially diagnosed as having bilateral nonsyndromic SNHL. Seven children underwent an audiological assessment before the age of 9 months. The earliest audiological examination was carried out at 1 and 3 months. The children with pathogenic variants in the USH2A gene in our examined group were identified in the first year of life via UNHS. The hearing threshold levels (HTL) for the USH2A group are compactly distributed between 51.25 dB and 66.25 dB, quartiles are 54 dB and 63.4 dB, with a median of 60 dB. The audiological profile of patients with biallelic USH2A mutations differs from audiograms of patients who had STRC-related hearing loss. We have not found any significant elevation in hearing thresholds in the first decade of life. We also estimated the prevalence of the USH2A and STRC mutations among GJB2-negative infants with bilateral nonsyndromic SNHL examined under 12 months, and it was 7.5% and 16.1%, respectively. ConclusionAccording to our results, the early hearing phenotype in pediatric patients with biallelic mutations in the USH2A- gene is characterized by nonsyndromic mild-to-moderate SNHL in the first decade of life. Our results indicate that the presence of mutations in the USH2A or STRC genes can be expected in a child with congenital mild-to-moderate nonsyndromic SNHL. This information is of practical importance for parents, as they have to know the prognosis of hearing loss for their child from the very beginning. Post-screening follow-up should include adequate clinical, genetic, and social support for children and their parents.

Which threshold do we trust? A comparison of threshold measurements in adult bone-conduction device users and normal hearing adults

ObjectivesAdvancements in prescriptive formulae for bone-conduction hearing devices (BCDs) have highlighted the importance of measuring in-situ bone-conduction hearing thresholds. In-situ measurements are performed within the BCD manufacturer's software, using the patient's BCD as a transducer. While in-situ testing is a different approach than standard diagnostic bone-conduction testing, both approaches are in fact measuring the same inner ear hearing. Despite this, each approach may result in different thresholds for the same individual. This study aimed to answer the following question: In adults with normal hearing and adults who currently wear a bone-conduction device, are there differences and, if so, how large are these differences when thresholds are measured using different approaches? DesignBone-conduction hearing thresholds were measured for a group 32 normal hearing participants and a group 15 percutaneous BCD users. The normal hearing participants were tested in two conditions: (1) in-situ, with a BCD worn on a soft-band and (2) with the B71 bone-conduction diagnostic transducer. The BCD users were tested in these two conditions and (3) in-situ with a BCD attached to their abutment. In-situ hearing thresholds were measured with BCDs from two manufacturers. The mean intra-subject differences between these conditions were calculated. ResultsFor the normal hearing participants, BCD softband thresholds were poorer than the thresholds obtained with the diagnostic transducer across all tested frequencies. The average differences between the BCD softband thresholds and the diagnostic transducer were particularly large in the high frequencies (13 to 35 dB from 3 to 6 kHz). Similar differences were observed for the BCD user participants when comparing their BCD softband thresholds to the diagnostic transducer thresholds. The in-situ percutaneous thresholds were on average better than the diagnostic bone-conduction thresholds, although the differences were not statistically significant. Skin attenuation, calibration differences, and BCD characteristics were contributing factors to these differences. ConclusionsThe intra-subject differences measured in this study confirmed that using different bone-conduction transducers results in the measurement (i.e., recording) of different hearing threshold levels. These results support the necessity for a measurement tool able to measure audibility at threshold independent of the various coupling configurations used in bone-conduction amplification. An effective measurement tool would be required to take into account, or bypass, the factors contributing to the differences measured in this study. Until such a tool is commercially available, clinicians will continue to face uncertainty when fitting and attempting to assess the audibility of passive transcutaneous BCDs.

Hearing status of people occupationally exposed to ultrasonic noise.

The aim of the study was to evaluate the hearing status of operators of low-frequency ultrasonic devices compared to employees exposed to audible noise at a similar A-weighted sound pressure level (SPL) but without ultrasonic components. Standard pure-tone audiometry, extended high-frequency audiometry (EHFA), transient-evoked otoacoustic emissions (TEOAE), and distortion-product otoacoustic emissions (DPOAE), as well as questionnaire surveys were conducted among 148 subjects, aged 43.1±10.8 years, working as ultrasonic device operators for 18.7±10.6 years. Their exposure to noise within the ultrasonic and audible frequency range was also evaluated. The control group comprised 168 workers, adjusted according to gender, age (±2 years), tenure (±2 years), and the 8-hour daily noise exposure level (LEX,8h) of ±2 dB. The ultrasonic device operators and the control group were exposed to audible noise at LEX,8h of 80.8±3.9 dB and 79.1±3.4, respectively. The Polish maximum admissible intensity (MAI) values for audible noise were exceeded in 16.8% of the ultrasonic device operators, while 91.2% of them were exposed to ultrasonic noise at SPL>MAI values. There were no significant differences between the groups in terms of the hearing threshold levels (HTLs) up to 3 kHz, while the ultrasonic device operators exhibited significantly higher (worse) HTLs, as compared to the control group, in the range of 4-14 kHz. The results of the DPOAE and TEOAE testing also indicated worse hearing among the ultrasonic device operators. However, the differences between the groups were more pronounced in the case of EHFA and DPOAEs. The outcomes of all hearing tests consistently indicated worse hearing among the ultrasonic device operators as compared to the control group. Both EHFA and DPOAE seem to be useful tools for recognizing early signs of hearing loss among ultrasonic device operators. nt J Occup Med Environ Health. 2022;35(3):309-25.

A genetic algorithm-based support vector machine model for detection of hearing thresholds

ABSTRACT Auditory evoked potentials (AEPs), which are detected on the EEG auditory cortex area, are very small signals in response to a sound stimulus (or electric) from the inner ear to the cerebral cortex. These signals are recorded from electrodes attached to the scalp and are used for measuring the bioelectric function of the auditory pathway. In order to characterise their dynamic behaviour and due to the complex behaviour of nonlinear dynamic properties of EEG signals, several nonlinear analyses have been performed. In this work, Detrented Fluctuation Analysis (DFA) is applied to estimate the Fractal Dimension (FD) from the recorded AEP signals of the normal and the impaired hearing subjects. This aims at detecting their hearing threshold level. With the aim of classifying both groups, the normal and hearing impaired subjects, a hybrid approach based on the Support Vector machines (SVM) and genetic algorithms (GA) is taken: GA is applied to simultaneously optimise both SVM kernel parameters and feature subset selection. Our results indicate that the hybrid GA-SVM is promising; it is able to determine well the SVM kernel parameters along with feature subset selection, which will result in a high classification accuracy.

Childhood hearing impairment and fertility in Norway

There is a lack of studies assessing how hearing impairment relates to reproductive outcomes. We examined whether childhood hearing impairment (HI) affects reproductive patterns based on longitudinal Norwegian population level data for birth cohorts 1940–1980. We used Poisson regression to estimate the association between the number of children ever born and HI. The association with childlessness is estimated by a logit model. As a robustness check, we also estimated family fixed effects Poisson and logit models. Hearing was assessed at ages 7, 10 and 13, and reproduction was observed at adult ages until 2014. Air conduction hearing threshold levels were obtained by pure-tone audiometry at eight frequencies from 0.25 to 8 kHz. Fertility data were collected from Norwegian administrative registers. The combined dataset size was N = 50,022. Our analyses reveal that HI in childhood is associated with lower fertility in adulthood, especially for men. The proportion of childless individuals among those with childhood HI was almost twice as large as that of individuals with normal childhood hearing (20.8% vs. 10.7%). The negative association is robust to the inclusion of family fixed effects in the model that allow to control for the unobserved heterogeneity that are shared between siblings, including factors related to the upbringing and parent characteristics. Less family support in later life could add to the health challenges faced by those with HI. More attention should be given to how fertility relates to HI.

COMPARISON OF HEARING OUTCOMES AFTER STAPES SURGERY DEPENDING ON PROSTHESIS TYPE: A RETROSPECTIVE ANALYSIS.

Stapes surgery is generally performed to treat otosclerosis, and there are numerous surgical techniques and prosthesis materials available. Critical evaluation of postoperative hearing outcomes is crucial for identification and further improvement of treatment options. This study is a non-randomized retrospective analysis of hearing threshold levels before and after stapedectomy or stapedotomy in 365 patients during a twenty-year period. The patients were classified into three groups depending on the prosthesis and surgery type: stapedectomy with Schuknecht prosthesis placement and stapedotomy with either Causse or Richard prosthesis. The postoperative air-bone gap (ABG) was calculated by subtracting the bone conduction pure tone-audiogram (PTA) from the air conduction PTA. Hearing threshold levels were evaluated preoperatively and postoperatively from 250 Hz to 12 kHz. The results showed air-bone gap reduction <10 dB in 72% patients, 70% of patients, and 76% of patients using Schucknecht's prosthesis, Richard prosthesis, and Causse prosthesis, respectively. The results did not differ significantly between three prothesis types. Choice of prosthesis should be made individually for each patient, but surgeon competency is still the most important outcome variable, regardless of prosthesis type.

Does Exposure to Noise During Military Service Affect the Progression of Hearing Loss with Increasing Age?

It is traditionally believed that the effects of exposure to noise cease once the exposure itself has ceased. If this is the case, exposure to noise relatively early in life, for example during military service, should not affect the subsequent progression of hearing loss. However, recent data from studies using animals suggest that noise exposure can accelerate the subsequent progression of hearing loss. This paper presents new longitudinal data obtained from 29 former male military personnel. Audiograms obtained at the end of military service were compared with those obtained at least five years later. Rates of change of hearing threshold level (HTL) in dB/year were compared with those expected from ISO7029 (2017) for men at the 50th percentile. The results are consistent with the hypothesis that noise exposure during military service accelerates the progression of hearing loss for frequencies where the hearing loss is absent or mild at the end of military service, by about 1.7 dB/year on average for frequencies from 3 to 8 kHz, but has no effect on or slows the progression of hearing loss for frequencies where the hearing loss exceeds about 50 dB. Acceleration appears to occur over a wide frequency range, including 1 kHz. There remains a need for further longitudinal studies using larger sample sizes. Longitudinal studies are also needed to establish whether exposure to other types of sounds, for example at rock concerts or from work in heavy industries, affects the subsequent progression of hearing loss.

Guidelines for Diagnosing and Quantifying Noise-Induced Hearing Loss.

This paper makes recommendations for the diagnosis and quantification of noise-induced hearing loss (NIHL) in a medico-legal context. A distinction is made between NIHL produced by: steady broadband noise, as occurs in some factories; more impulsive factory sounds, such as hammering; noise exposure during military service, which can involve very high peak sound levels; and exposure to very intense tones. It is argued that existing diagnostic methods, which were primarily developed to deal with NIHL produced by steady broadband noise, are not adequate for the diagnosis of NIHL produced by different types of exposures. Furthermore, some existing diagnostic methods are based on now-obsolete standards, and make unrealistic assumptions. Diagnostic methods are proposed for each of the types of noise exposure considered. It is recommended that quantification of NIHL for all types of exposures is based on comparison of the measured hearing threshold levels with the age-associated hearing levels (AAHLs) for a non-noise exposed population, as specified in ISO 7029 (2017), usually using the 50th percentile, but using another percentile if there are good reasons for doing so. When audiograms are available both soon after the end of military service and some time afterwards, the most recent audiogram should be used for diagnosis and quantification, since this reflects any effect of the noise exposure on the subsequent progression of hearing loss. It is recommended that the overall NIHL for each ear be quantified as the average NIHL across the frequencies 1, 2, and 4 kHz.

Vestibular function of pediatric patients with sudden sensorineural hearing loss: based on vertigo symptom and vestibular function testing.

This study aimed to evaluate the relationship between vestibular and auditory functions in pediatric patients with sudden sensorineural hearing loss (SSHL). A total of 30 pediatric patients experiencing unilateral SSHL between 5.9 and 13.0years of age were enrolled in this study. Pure tone audiometry was evaluated prior to treatment initiation and again after one month of treatment. Prior to treatment initiation, vertigo symptoms were noted; then several vestibular function tests were conducted including caloric testing, ocular vestibular evoked myogenic potentials (o-VEMPs) and cervical vestibular evoked myogenic potentials (c-VEMPs). Associations between pre and post-treatment vestibular function and hearing threshold levels were analyzed. Initial hearing thresholds of children with vertigo were higher than thresholds of children without vertigo (92dB vs 79dB, P = 0.033), while initial hearing thresholds of children with abnormal caloric test findings were higher than thresholds of children with normal caloric test findings (93dB vs 67dB, P = 0.014). Cutoff values of hearing thresholds for those with vertigo symptoms and abnormal vestibular test results were 86.000- and 89.583-dB HL, respectively. Regarding prognosis, children with vertigo exhibited lower recovery rates than children without vertigo (33% vs 75%, P = 0.025); recovery rates of children with abnormal caloric test results were lower than the overall recovery rate (25% vs 73%, respectively, P = 0.039). Assessments of vertigo symptoms and vestibular function are useful tools in predicting pediatric SSHL patient disease severity and prognosis.

Prevalence, behavioural, and management outcomes of infants with auditory neuropathy spectrum disorder.

To provide an overview of electrophysiological and behavioural outcomes from a large UK centres data set on children diagnosed with auditory neuropathy (ANSD) between 2002 and March 2018. A systematic audit was undertaken, collating the electrophysiological data from auditory brainstem response (ABR) follow-up, risk factors, and later behavioural results/management. These were then compared to look for trends between groups. The study sample consisted of 118 925 infants born, with 46 (0.039%, 0.39 per 1000 births) being diagnosed with congenital ANSD (39 bilateral, seven unilateral). Twenty-nine per cent of ears with ANSD had short latency components on ABR testing. Forty-four per cent of ears with present cochlear microphonics but absent transient-evoked otoacoustic emissions (TE-OAE) and no ABR went on to have profound behavioural hearing threshold levels. All but one child went on to show a hearing loss on behavioural testing. ANSD was not confined to the population from neonatal intensive care units: there were three bilateral and five unilateral cases in the typically developing infant population. The incidence of ANSD is higher in this sample than that reported previously in the literature. Children who had cochlear microphonics with absent ABR and absent TE-OAE had significantly worse later behavioural outcomes than other patterns of electrophysiological results.

The correlation between glycosylated haemoglobin levels with pure tone average values in type 2 diabetes mellitus patients

Hearing plays an important role in our daily activities, if it is impaired or lost the quality of life is affected by improper communication. The diabetes mellitus is a chronic metabolic disorder and affects all the systems in the body including auditory system. So assessment of hearing is important in diabetics to know the type, extent of hearing impairment which helps to take treatment decisions and preventive measures. Present study is focused on relationship between glycosylated haemoglobin (HbA1c) levels with pure tone average (PTA) values in type 2 diabetics. Type 2 diabetic patients with (WHI) and without (WoHI) hearing impairment, both the gender was included with age limit between 35-55 years and also ten normal subjects were included as controls. Pure tone average (PTA) is the average of hearing threshold levels at different frequencies; it gives information about an individual’s hearing level in each ear. All the data were expressed as mean ± SE. The mean were analyzed by one way ANOVA. Pearson correlation test was done to see the relationship between right and left ear PTA values in normal subjects, WoHI and WHI groups with HbA1c values. In both the groups pure tone average values are not statistically correlated with HbA1c. The left ear of both WoHI (P=0.977) and WHI (P=0.490) groups shows negative correlation with HbA1c. The HbA1c values are correlated with PTA values in all subjects. The pure tone audiometry is helpful to know the status of hearing sensitivity and type, severity of the hearing impairment in the T2DM patients in relation to HbA1c levels.

Audiometric assessment of hearing loss sustained during military service

An analysis is presented of the audiograms, obtained using Telephonics TDH39 headphones (Huntington, NY), of 80 men claiming compensation for noise-induced hearing loss (NIHL) sustained during military service. A comparison with an independent database of audiograms collected using other headphones suggested that no adjustment was needed to the hearing threshold levels (HTLs) at 6 kHz to allow for the use of TDH39 headphones. The method of Moore [(2020). J. Acoust. Soc. Am. 148, 884-894] for diagnosing military noise-induced hearing loss (M-NIHL) gave a positive diagnosis for 92.5% of right ears and 97.5% of left ears. The mean HTLs were maximal and similar at 4, 6, and 8 kHz but with considerable individual variability. A comparison with age-expected HTLs showed that M-NIHL was typically greatest at 3, 4, 6, or 8 kHz but with considerable individual variability. M-NIHL values were positive from 0.5 to 8 kHz. The HTLs were significantly higher for the left than for the right ears, but the asymmetry varied across individuals and could usually be ascribed to specific features of the noise exposure. The asymmetry existed over the range from 0.5 to 8 kHz, supporting the idea that M-NIHL occurs over a wide frequency range. Tinnitus was reported by 76 of the 80 men.