Distortion-product otoacoustic emissions in workers exposed to urban stressors

Effect of noise and hand-transmitted vibration exposure on hearing and equilibrium under a simulated work environment with building tools

BACKGROUND

Construction workers are exposed to hand-transmitted vibration (HTV) and/or noise caused by vibrating hand tools in the work environment.

OBJECTIVE

The present study aims to investigate the effects of exposure to HTV and/or noise on workers' hearing loss and body balance.

METHODS

Forty construction workers were exposed to HTV (10 m/s2 rms, 31.5 Hz) and/or typical construction noise (90 dBA) in three simulated experiment scenarios with the vibrating hand-held tool for 30 minutes over three days. The hearing loss from 1000 to 6000 Hz and the body balance were determined before and after each exposure scenario.

RESULTS

Separate noise exposure at all frequencies except for 1000 Hz could significantly affect hearing threshold levels (p-value<0.05). Separate exposure to HTV cannot lead to a remarkable effect on hearing loss (p-value>0.05); however, it can synergistically increase the effect of noise on hearing loss. Also, the affected frequency range in concurrent exposure has been greater than in separate noise exposure. The separate effects of exposure to HTV and noise on the subjects' body balance were not statistically significant (p-value>0.05); however, these effects became significant in concurrent exposure (p-value<0.05). Based on the estimated effect sizes, noise could synergistically increase the observed effect of HTV on body balance.

CONCLUSION

There is a synergistic interaction between HTV and noise on hearing loss and body balance. It seems necessary to pay attention to the risk evaluation of simultaneous exposure to noise and HTV when setting the occupational action limit values.

Association Analysis of Candidate Gene Polymorphisms and Audiometric Measures of Noise-Induced Hearing Loss in Young Musicians

INTRODUCTION

This study aimed to investigate the association between candidate genetic variants and audiometric measures of noise-induced hearing loss (NIHL) in young musicians.

METHODS

The study analyzed a database by Phillips et al. (Feasibility of a bilateral 4000-6000 Hz notch as a phenotype for genetic association analysis. Int J Audiol 2015;54:645-52.) which included behavioral hearing thresholds, distortion-product otoacoustic emissions (DPOAE), tympanometric, and genetic data of 166 participants meeting the inclusion criteria. Nineteen single nucleotide polymorphisms (SNPs) in 13 cochlear genes previously associated with NIHL in factory workers were included in the present investigation. The average hearing threshold at 3000 and 4000 Hz (AHT) and average DPOAE signal to noise ratio (DPOAE SNR) in both ears were calculated.

RESULTS

The regression analyses showed that two SNPs- one in KCNE1 (rs2070358) and the other in CAT (rs12273124) revealed a statistically significant relationship with DPOAE SNR in both ears. Two SNPs in MYH14 and one in GJB4 revealed a significant association with DPOAE SNR in the left ear. Two SNPs in HSP70, one in CDH23 and one in KCNJ10 showed significant association with DPOAE SNR in the right ear. None of the included SNPs showed association with AHT in both ears.

CONCLUSIONS

A genetic variant in KCNE1 was associated with the strength of the cochlear amplifier as assessed by DPOAE SNR. Musicians carrying causal genetic variants to NIHL might exhibit changes in their auditory functions early in the lifespan even when most subjects had their hearing thresholds within normal limits. These participants are likely to show the clinical manifestation of NIHL in the future if no preventive measures are applied.

Post Vaccinal Temporary Sensorineural Hearing Loss

In our systematic research we identified four studies concerning the onset of neurological adverse events following vaccination and two excluding this association. A 33-year-old Italian man, belonging to the Italian Army was hospitalized because he suffered from vertigo, nausea and sudden right hearing loss not classified (NDD), that set in 24 h after the administration of tetanus-diphtheria and meningococcal vaccines. Some neurological events arising after vaccination are very difficult to treat. In our case, the functional recovery on low and medium frequencies was possible about 6 months after the morbid event.

Work-Related Noise Exposure in a Cohort of Patients with Chronic Tinnitus: Analysis of Demographic and Audiological Characteristics

Work-related noise exposure is one of the major factors contributing to the development of adult-onset hearing loss and tinnitus. The aim of this study was to analyze, in patients with chronic tinnitus and long-term occupational noise exposure, (A) characteristics of hearing loss, tinnitus, comorbidities, demographic characteristics and a history of work-related noise exposure and (B) differences among individuals employed in occupations with high and low risk of developing work-related noise-induced hearing loss (NIHL). One hundred thirty six patients with chronic tinnitus and at least a 10 year-long working history were divided into two groups based on the risk of their profession to induce NIHL. Individuals employed in jobs at high risk for NIHL were mostly males and exhibited a poorer hearing threshold, more evident in the left ear. Tinnitus was mostly bilateral; the next largest presentation was left-sided; patients described their tinnitus as buzzing or high-pitched. Correlation between age, length of tinnitus and worse hearing was found. Patients with a higher degree of hearing impairment were mostly males and were more likely to have a family history of hearing loss and at least one cardiovascular comorbidity. Our study shows some differences in individuals with tinnitus and a history of a profession associated with increased exposure to NIHL compared to those without such a history.