The influence of occupational noise exposure on blood pressure and hearing loss among female workers of childbearing age.

OBJECTIVES: Women exposed to occupational noise experience adverse pregnancy outcomes. Therefore, we initiated a large, population-based, cross-sectional study to further investigate the effects of occupational noise on hearing and blood pressure among female workers of childbearing age. STUDY DESIGN AND SETTING: A total of 6981 childbearing-aged female workers were selected for this cross-sectional study. Basic characteristics of participants were analyzed by comparing the exposed and control groups. Logistic regression models were employed to calculate the odds ratios (ORs) and 95% confidences intervals (CIs) for the associations of occupational noise with levels of hearing loss and blood pressure. The associations were further explored through stratification by age and duration of noise exposure. RESULTS: Compared with participants not exposed to occupational noise, increasing years of occupational noise exposure were independently associated with an elevated risk of hypertension after adjustment of age, industry classification, enterprise size and economic type. Compared to participants not exposed to occupational noise, only the prevalence of bilateral hearing loss was significantly higher after adjustments for age, industry classification, enterprise size and economic type. Compared with those with normal hearing, the ORs and 95% CIs were 1.97 (0.95-4.07), 2.22 (1.05-4.68) and 1.29 (1.06-1.57) for bilateral, unilateral and any ear hearing loss, respectively. CONCLUSIONS: Occupational noise exposure is positively associated with both hypertension and bilateral hearing loss among female workers of childbearing age. Those exposed to occupational noise show an increased risk of hypertension after adjusting for potential confounders.

Impulsive pile driving sound does not induce hearing loss in the longfin squid (Doryteuthis pealeii)a).

Offshore windfarms are a key means to produce clean energy as we seek to limit climate change effects. Impulsive pile driving used for their construction in shallow water environments is among the most intense anthropogenic sound sources. There is an increasing understanding that an array of marine invertebrates detects acoustic cues, yet little is known about how pile driving sound could impact their sound detection abilities. We experimentally quantified potential changes in sound sensitivity for an abundant, commercially and ecologically important squid species (Doryteuthis pealeii) exposed to actual in situ pile driving. The pile was 0.3-m diameter and 10-m long; hammer energy reached 16 kJ per strike. Sound detection thresholds were determined using auditory evoked potentials in animals with no exposure, after one 15-min or five repeated 15-min long pile driving sound sequences, corresponding to cumulative sound exposure levels of 110 and 131 dB re (1 µm s-2)2 s for acceleration and 187 and 214 dB re (1 µPa)2 s for pressure. We found no statistical evidence of temporary threshold shifts in any squid exposed to pile driving sound sequences. These results, combined with companion behavioral studies, suggest that squid may be robust to the sound impacts during offshore windfarm construction.

Effects of Ultrasonic Use on Hearing Loss in Dental Hygienists: A matched pairs design study.

Purpose Dental professionals are exposed to hazardous noise levels on a daily basis in clinical practice. The purpose of this study was to compare the hearing status of dental hygienists who utilize ultrasonic scalers in the workplace compared to age-matched control participants (non-dental hygienists) who were not exposed to ultrasonic noise.Methods A convenience sample of nineteen dental hygienists (experimental) and nineteen non-dental hygienists (control) was recruited for this study. A matched pairs design was utilized; participants in each group were matched based on age and gender to eliminate confounding variables. The testing procedure consisted of an audiologist performing a series of auditory tests including otoacoustic emissions test, pure-tone audiometry, and tympanometry on the experimental and control groups.Results In the right ear, there were notable differences from 1000 Hz - 10,000 Hz and in the left ear from 6000 Hz - 10,000 Hz, with higher hearing thresholds in the experimental group of dental hygienists. While 56% of the univariate tests conducted on how many days were worked per week showed statistical significance, the regression line slope indicated those that worked more days had better hearing statuses. The variables for years in practice for dental hygienists, how many of those years were full-time employment, and how many years the dental hygienist had used an ultrasonic scaling device, also had many significant univariate tests for the experimental group only. These variables were more likely to serve as proxies representing true noise exposure. The paired t-test between the groups demonstrated statistically significant differences between the experimental and control group at 9000 Hz in both ears.Conclusion While results from this study demonstrated various qualitative differences in hearing status of the control group (non-dental hygienists) and experimental group (dental hygienists), age was found to be the most critical variable. Furthermore, this data demonstrated differences in hearing status based on various frequencies between dental hygienists and age-matched controls that should be further explored with a larger population.

Comparison of the risk of noise-induced hearing loss between male police officers and male non-police officers: a nationwide cohort study using propensity score matching in South Korea.

BACKGROUND: Police officers are at a high risk of noise-induced hearing loss (NIHL) owing to the nature of their work. Therefore, this study aimed to compare the risk of NIHL in police officers and controls. METHODS: This study used the National Health Insurance claims data of workers aged 25-65 years obtained from 2005 to 2015. The case group comprised police officers, while the control group comprised general workers and public officers. The study followed a three-phase cohort design. The standardized incidence ratio (SIR) was calculated using an indirect standardization method based on age. Propensity score matching was performed using the greedy matching method, with a police officer-to-control group ratio of 1:3. Cox regression analysis was performed for each matched control group. Statistical significance was determined by a lower limit of greater than 1, based on the 95% confidence interval (CI). RESULTS: The SIR values for police officers were 1.62 (95% CI: 1.44-1.82) compared with general workers and 1.78 (95% CI: 1.66-1.73) compared with public officers. Police officers exhibited an increased risk of NIHL compared with general workers (hazard ratio (HR): 1.71, 95% CI: 1.49-1.98) and public officers (HR: 2.19, 95% CI: 1.88-2.56). CONCLUSIONS: It is necessary to prevent NIHL by reducing occupational noise exposure through measures such as wearing earplugs, improving shooting training methods, and improving the shift work system.

[Whole brain causal functional connectivity analysis of noise-induced deafness based on resting state-functional magnetic resonance imaging].

Objective: To investigate the changes of directional connections of auditory and non-auditory in patients with noise-induced deafness (NID) by degree centrality (DC) and Granger causality analysis (GCA), and to explore the mode of brain function remodeling after NID. Methods: In October 2023, a total of 58 patients diagnosed with NID by the Occupational Diseases Department of Yantaishan Hospital of Yantai from 2014 to 2022 were collected as case group (NID group), and 42 healthy volunteers matched by gender, age and education level were selected as the control group (HC group). Resting state-functional magnetic resonance imaging (Rs-fMRI) was perfomed and PC analysis was performed. The brain regions with statistically significant differences in DC values between groups and the bilateral Heschl regions were extracted as regions of interest (ROI) for voxel-based whole brain GCA and correlation analysis. Results: Compared with HC group, the SOG.L DC value of NID group was lower, the connectivity values of SFGdor.L to SOG.L was increased, the connectivity value of PCL.L to SOG.L was decreased, the connectivity values of ORBmid.L, PCG.R and CUN. L/R to HES.L were increased, the connectivity value of SFGdor.L to HES.L was decreased, the connectivity value of HES.L to PCUN.L was decreased, the connectivity values of ORBsup.L and PCG.R to HES.R were increased, the connectivity value of HES.R to CUN.L was decreased (P voxel level<0.01, P cluster level<0.05). The connectivity value of PCL.L to SOG.L was negatively correlated with the weighted value of the better whisper frequency (P<0.05) . Conclusion: The NID patients have abnormal directional connectivity activity in multiple brain regions, such as auditory vision, executive control, somatosensory movement, and default mode network. It is suggested that hearing loss may cause complex neural remodeling between auditory and non-auditory centers.

Analysis of Therapeutic Options for Noise-Induced Hearing Loss: Retroauricular Injection of Methylprednisolone Sodium Succinate Combined with Hyperbaric Oxygenation.

OBJECTIVE: To evaluate the clinical effect of retroaural injection of methylprednisolone sodium succinate combined with hyperbaric oxygen (HBO) on the treatment of noise-induced hearing loss. METHODS: Case data of 220 patients with hearing loss treated at the Zhongda Hospital Southeast University from January 1, 2019 to August 1, 2023 were obtained. As per the treatment plan, the recruited patients were divided into two cohorts: 158 cases in the combined-treatment group (retroaural injection of methylprednisolone sodium succinate combined with HBO) and 62 cases in the single-hormone group (retroaural injection of methylprednisolone sodium succinate). Comparison of the clinical efficacies and postoperative complication rates of the two groups was performed after treatment. MS-Excel was used to build a database for all data, and SPSS26.0 was utilized in the statistical analysis of recorded data. RESULTS: For patients with low-frequency, high-frequency, and flat descending type, the combined-treatment group showed significantly higher clinical effective rate than the single-hormone group (P < 0.05). For patients with disease duration ≤7 days, the combined-treatment group attained a significantly higher clinical effective rate was than the single-hormone group (P < 0.05). The safety of patients in both groups was evaluated mainly through their adverse reactions. The total incidence of adverse reactions in the single-hormone group reached 9.68%, and that in the combined-treatment group was 8.23%. The two groups revealed no significant difference in terms of incidence of adverse reactions (P > 0.05). CONCLUSION: HBO combined with retroaural injection of methylprednisolone sodium succinate has good clinical efficacy and safety in the treatment of hearing loss.

Full of sound and fury.

The subject of noise in the operating theatre was recognized as early as 1972 and has been compared to noise levels on a busy highway. While noise-induced hearing loss in orthopaedic surgery specifically has been recognized as early as the 1990s, it remains poorly studied. As a result, there has been renewed focus in this occupational hazard. Noise level is typically measured in decibels (dB), whereas noise adjusted for human perception uses A-weighted sound levels and is expressed in dBA. Mean operating theatre noise levels range between 51 and 75 dBA, with peak levels between 80 and 119 dBA. The greatest sources of noise emanate from powered surgical instruments, which can exceed levels as high as 140 dBA. Newer technology, such as robotic-assisted systems, contribute a potential new source of noise. This article is a narrative review of the deleterious effects of prolonged noise exposure, including noise-induced hearing loss in the operating theatre team and the patient, intraoperative miscommunication, and increased cognitive load and stress, all of which impact the surgical team's overall performance. Interventions to mitigate the effects of noise exposure include the use of quieter surgical equipment, the implementation of sound-absorbing personal protective equipment, or changes in communication protocols. Future research endeavours should use advanced research methods and embrace technological innovations to proactively mitigate the effects of operating theatre noise.

Exposure to Noise or Music in Clinical Trials: A Scoping Review on Ethical and Methodological Considerations.

BACKGROUND: Use of noise or music in experimental human studies requires balancing the need to avoid subjecting participants to potentially harmful noise levels while still reaching levels that will produce a measurable change in the primary outcome. Several methodological and ethical aspects must be considered. This study aims to summarize ethical and methodological aspects, and reported outcomes, of previously published experimental paradigms using loud noise/music. METHODS AND MATERIALS: Four databases (Medline, Central, Web of Science, and Scopus) and two trials registries (Clinicaltrials.gov and EU Clinical Trials) were searched. Extracted items had the details of author and year of publication, study design and purpose, population, setting timeline and material, selected battery test, and effect of noise/music on participants' hearing. RESULTS: Thirty-four studies were included. Exposure safety considerations were reported in five studies. Eleven studies assessing hearing loss used white or narrow-band noise [(NBN (0.5-4 kHz), up to 115 dBA, duration range: 3'-24 hours)], and 10 used pop music (up to 106 dBA, duration range: 10'-4 hours). Experimental setting varied significantly. Temporary thresholds shift (TTS) and reduction in distortion product otoacoustic emissions were found at 1-8 kHz, with maximum average TTS∼21.5 dB at 4 kHz after NBN and ∼11.5 dB at 6 kHz after music exposure. All participants recovered their hearing, except for one participant in one study. In the 13 non-hearing loss studies, no hearing testing was performed after exposure, but loud noise was associated with temporary stress, bradygastria, and cardiovascular changes. Noise-induced subjective stress may be higher for participants with tinnitus. Loud noise (100 dBA, 10') increased diastolic and mean blood pressure only in participants with hypertension. CONCLUSION: Experimental exposure paradigms can produce temporary changes to hearing without measurable long-term health consequences. Methodological and ethical aspects identified in this review should be considered for the development of future paradigms.

Assessment of Noise Exposure and Risk of Hearing Loss for Young People in Amusement Arcades.

BACKGROUND: Amusement arcades are one of the most popular entertainment venues for young people, but excessive noise levels inside them could harm young people's hearing. The aim of this study is to assess the characteristics and risk of noise exposure for young people in amusement arcades and understand their knowledge of and attitudes towards safe listening. METHODS: In this study, noise measurement was conducted in five large amusement arcades to collect 40 noise samples. At the same time, questionnaires were used in each amusement arcade to investigate young players' social information, subjective perception, and cognition of noise-induced hearing loss (NIHL). RESULTS: The level of the noise samples ranged from 83.05 to 89.4 dBA. There are significant differences in noise levels between amusement arcades (P < 0.05), but there is no significant difference in noise levels between different games (P > 0.05). The subjective questionnaire survey shows that 61.9% of young people feel that the sound of video games is noisy or very noisy, but it is worth noting that 63.5% of them do not know or think that noise will not cause hearing loss, and 39.7% of people will choose to do nothing to help them endure the noise in such an environment. For safe listening, young people are more inclined to choose measures to stay in quiet areas and reduce the volume of game devices. CONCLUSIONS: The noise levels in most amusement arcades have exceeded the exposure limits recommended by the Environment Protection Agency (EPA); subjective questionnaires also indicate that internal noise levels may cause hearing loss, and young customers did not know enough about safe listening. For young people's hearing safety, these issues need more attention.

Crafting Strategies for Promoting Healthy Ear and Hearing Care: Making It Happen.

Globally, hearing loss is a prevalent health condition that often goes unattended and significantly influences the quality of life of the affected individual. The prevalence of hearing loss is expected to rise in the years to come, predominantly due to the changes in the demography, increased exposure to recreational noise, and disregarding ear conditions that can account for hearing loss but are immensely preventable. A wide range of activities can be planned and organized to promote ear and hearing care and thereby contribute to our vision to prevent the consequences of unaddressed hearing loss. However, the sustainability of these events, especially in terms of accomplishing the intended outcomes, essentially depends on the involvement of the community and the political leaders. In conclusion, the strategies to promote ear and hearing care are much more essential than health interventions do; rather, these measures have social implications. The need of the hour is to create awareness among different stakeholders to ensure that we can change the perception of the masses and that ear and hearing care becomes a global public health priority.

Activated tissue-resident macrophages contribute to hair cell insults in noise-induced hearing loss in mice.

Macrophages serve as the primary immune cell population and assume a pivotal role in the immune response within the damaged cochleae. Yet, the origin and role of macrophages in response to noise exposure remain controversial. Here, we take advantage of Ccr2RFP/+ Cx3cr1GFP/+ dual-reporter mice to identify the infiltrated and tissue-resident macrophages. After noise exposure, we reveal that activated resident macrophages change in morphology, increase in abundance, and migrate to the region of hair cells, leading to the loss of outer hair cells and the damage of ribbon synapses. Meanwhile, peripheral monocytes are not implicated in the noise-induced hair cell insults. These noise-induced activities of macrophages are abolished by inhibiting TLR4 signaling, resulting in alleviated insults of hair cells and partial recovery of hearing. Our findings indicate cochlear resident macrophages are pro-inflammatory and detrimental players in acoustic trauma and introduce a potential therapeutic target in noise-induced hearing loss.

[Measurement and evaluation of personal attenuation rating before and after the training of the noise-exposed workers wearing foam earplugs].

Objective: To measure and compare the difference of personal attenuation rating (PAR) of the workers wearing foam earplugs before and after the training, and to evaluate the effect of ear protector wearing training on the noise protection. Methods: In February 2023, 94 workers exposed to noise in a machinery manufacturing factory were selected as subjects. The production noise in the workplace was measured and subjects were trained to wear earplugs. The PAR values of wearing 3M 1110 foam test earplugs were measured and recorded before and after the training by using the fit testing of hearing protection device. The differences between the actual PAR values with nominal values and the noise attenuation values in related standards were compared, and the protective effect of hearing protection device before and after training was evaluated. Results: The average age of the subjects was (36.76±11.48) years old, the average length of service was (16.34±11.64) years, and the average exposure time to noise was (15.67±11.64) years. The noise detection results of the subjects' posts were ranged from 80.1 to 94.3 dB (A). The results of subjects wore 3M 1110 foam test earplugs for fit testing showed that the binaural PAR value after training was (19.3±6.4) dB (A), which was significantly higher than that before training (11.1±7.4) dB (A) (t=13.31, P<0.001). After training, 11 people (11.70%) could reach the corrected noise reduction value (NRR value), 26 people (27.66%) could reach the standard of single noise reduction value (SNR value) ×0.6, and 84 people (89.36%) could reach the standard of (NRR-7) /2. The under protection rate of hearing protectors after training (7.45%) was significantly lower than that before training (45.74%), and the difference of different protection levels before and after training was statistically significant (χ(2)=40.83, P<0.001) . Conclusion: It is suggested that enterprises should use the fit testing instead of nominal value estimation to evaluate the noise reduction effect of hearing protection device. Special training on the selection and use of hearing protection device should be strengthened, so as to ensure that workers wear them correctly and improve the protective effect of hearing protection device.

High-Frequency Hearing Loss Amongst Smart Mobile Phone Users: A Case-Control Study.

BACKGROUND: In past 20 years, there is increase in mobile phone users from 12.4 million to about 5.6 billion i.e 70 % of the world's population.[1] Electromagnetic radiations emitted from mobile phone damages inner ear, cochlea and outer hair cells of inner ear and auditory pathway (AP).[2]. MATERIALS AND METHODS: Case control study. Group 1, N=30 subjects, using mobile smart phones since past 1-5 years and exposure time more than 2 hours per day. Group II included 30 subjects, using mobile smart phones for more than 5 years and exposure time more than 2 hours per day. Headache, tinnitus, or sensations of burning around phone-using were excluded. Brainstem auditory evoked potential (BAEP) done. Student Unpaired t test was used for analysis and chisquare test. RESULTS: Mean ± SD of absolute latencies (AL) of Brainstem evoked response auditory. (BERA) waves III, V and all interpeak latencies at 80 dB and 4,6,8 KHz in group 2 were delayed and significant as compared to group 1. All parameters were highly significant at 8KHz as compared to 4KHz in group 2. CONCLUSION: Brain stem evoked response audiometry (BERA) detects hearing loss in smart mobile phone using subjects at higher frequencies i.e at 8 KHz early. Hence central neural axis involvement can be detected early by BERA.

Résumé Contexte:Au cours des 20 dernières années, le nombre d'utilisateurs de téléphones mobiles est passé de 12,4 millions à environ 5,6 milliards, soit 70 % de la population mondiale. [1] Les rayonnements électromagnétiques émis par les téléphones portables endommagent l'oreille interne, la cochlée et les cellules ciliées externes de l'oreille interne et des voies auditives (PA). [2]Matériels et méthodes:étude cas-témoins. Groupe 1, N = 30 sujets, utilisant des téléphones intelligents mobiles depuis 1 à 5 ans et temps d'exposition supérieur à 2 heures par jour. Le groupe II comprenait 30 sujets, utilisant des téléphones portables intelligents depuis plus de 5 ans et ayant une durée d'exposition supérieure à 2 heures par jour. Les maux de tête, les acouphènes ou les sensations de brûlure lors de l'utilisation du téléphone ont été exclus. Potentiel évoqué auditif du tronc cérébral (BAEP) réalisé. Le test t non apparié de Student a été utilisé pour l'analyse et le test du chi carré.Résultats:Moyenne ± écart-type des latences absolues (AL) de la réponse auditive évoquée du tronc cérébral. (BERA) les ondes III, V et toutes les latences inter-pics à 80 dB et 4,6,8 KHz dans le groupe 2 étaient retardées et significatives par rapport au groupe 1. Tous les paramètres étaient hautement significatifs à 8 KHz par rapport à 4 KHz dans le groupe 2.Conclusion:L'audiométrie à réponse évoquée du tronc cérébral (BERA) détecte la perte auditive dans un téléphone mobile intelligent en utilisant des sujets à des fréquences plus élevées, c'est-à-dire à 8 KHz plus tôt. Par conséquent, l'implication de l'axe neural central peut être détectée précocement par BERA.

The role of GDF15 in attenuating noise-induced hidden hearing loss by alleviating oxidative stress.

Noise-induced hidden hearing loss (HHL) is a newly uncovered form of hearing impairment that causes hidden damage to the cochlea. Patients with HHL do not have significant abnormalities in their hearing thresholds, but they experience impaired speech recognition in noisy environments. However, the mechanisms underlying HHL remain unclear. In this study, we developed single-cell transcriptome profiles of the cochlea of mice with HHL, detailing changes in individual cell types. Our study revealed a transient threshold shift, reduced auditory brainstem response wave I amplitude, and decreased number of ribbon synapses in HHL mice. Our findings suggest elevated oxidative stress and GDF15 expression in cochlear hair cells of HHL mice. Notably, the upregulation of GDF15 attenuated oxidative stress and auditory impairment in the cochlea of HHL mice. This suggests that a therapeutic strategy targeting GDF15 may be efficacious against HHL.

Calcitriol alleviates noise-induced hearing loss by regulating the ATF3/DUSP1 signalling pathway.

BACKGROUND: Calcitriol (Cal) is the most active metabolite of vitamin D and has antioxidant and anti-inflammatory properties. The aim of this study was to investigate the role of Cal in noise-induced hearing loss (NIHL) to further elucidate the mechanism of noise-induced oxidative stress in the mouse cochlea. METHODS: C57BL/6 J mice were given six intraperitoneal injections of Cal (500 ng/kg/d). After 14 days of noise exposure, auditory brainstem response (ABR) thresholds, and the cochlear outer hair cell loss rate were analysed to evaluate auditory function. Real-time fluorescence quantitative PCR, immunofluorescence and western blotting were performed in vitro after the treatment of cochlear explants with 100 µM tert-butyl hydroperoxide (TBHP) for 2.5 h and HEI-OC1 cells with 250 µM TBHP for 1.5 h. RESULTS: In vivo experiments confirmed that Cal pretreatment mitigated NIHL and outer hair cell death. The in vitro results demonstrated that Cal significantly reduced TBHP-induced cochlear auditory nerve fibre degradation and spiral ganglion neuron damage. Moreover, treatment with Cal inhibited the expression of oxidative stress-related factors (3-NT and 4-HNE) and DNA damage-related factors (γ-H2A.X) and attenuated TBHP-induced apoptosis in cochlear explants and HEI-OC1 cells. A total of 1479 upregulated genes and 1443 downregulated genes were screened in cochlear tissue 1 h after noise exposure. The level of transcription factor 3 (ATF3) was significantly elevated in HEI-OC1 cells after TBHP stimulation. Gene Transcription Regulation Database （GTRD）and Cistrome database analyses revealed that the downstream target gene of ATF3 is dual specificity phosphatase 1 (DUSP1). Cistrome DB Toolkit database results showed that the transcription factor of DUSP1 was ATF3. In addition, the ChIP-PCR results indicated that ATF3 might be a direct transcription factor of DUSP1. CONCLUSION: The results of our study suggest that Cal attenuates NIHL and inhibits noise-induced apoptosis by regulating the ATF3/DUSP1 signalling pathway.

Ototoxicity-related changes in GABA immunolabeling within the rat inferior colliculus.

Several studies suggest that hearing loss results in changes in the balance between inhibition and excitation in the inferior colliculus (IC). The IC is an integral nucleus within the auditory brainstem. The majority of ascending pathways from the lateral lemniscus (LL), superior olivary complex (SOC), and cochlear nucleus (CN) synapse in the IC before projecting to the thalamus and cortex. Many of these ascending projections provide inhibitory innervation to neurons within the IC. However, the nature and the distribution of this inhibitory input have only been partially elucidated in the rat. The inhibitory neurotransmitter, gamma aminobutyric acid (GABA), from the ventral nucleus of the lateral lemniscus (VNLL), provides the primary inhibitory input to the IC of the rat with GABA from other lemniscal and SOC nuclei providing lesser, but prominent innervation. There is evidence that hearing related conditions can result in dysfunction of IC neurons. These changes may be mediated in part by changes in GABA inputs to IC neurons. We have previously used gene micro-arrays in a study of deafness-related changes in gene expression in the IC and found significant changes in GAD as well as the GABA transporters and GABA receptors (Holt 2005). This is consistent with reports of age and trauma related changes in GABA (Bledsoe et al., 1995; Mossop et al., 2000; Salvi et al., 2000). Ototoxic lesions of the cochlea produced a permanent threshold shift. The number, intensity, and density of GABA positive axon terminals in the IC were compared in normal hearing and deafened rats. While the number of GABA immunolabeled puncta was only minimally different between groups, the intensity of labeling was significantly reduced. The ultrastructural localization and distribution of labeling was also examined. In deafened animals, the number of immuno gold particles was reduced by 78 % in axodendritic and 82 % in axosomatic GABAergic puncta. The affected puncta were primarily associated with small IC neurons. These results suggest that reduced inhibition to IC neurons contribute to the increased neuronal excitability observed in the IC following noise or drug induced hearing loss. Whether these deafness diminished inhibitory inputs originate from intrinsic or extrinsic CNIC sources awaits further study.

Noise in operating theatres, is it safe?

INTRODUCTION: Noise-Induced Hearing Loss (NIHL) is a condition caused by repeated exposure to loud noise, with operating theatre personnel potentially at risk. The aims of this study were to establish the typical noise levels in orthopaedic theatres and to compare these to The Control of Noise at Work Regulations 2005. MATERIALS AND METHODS: We measured the average noise levels in 40 trauma and orthopaedic surgeries in a single centre. We used the Decibel X app to take measurements, then performed corrections to ascertain noise levels at the surgeon's ear (Leq). The daily noise exposure level for theatre staff for each procedure (LEP, d) and the LEP, d over an average 8-hour working day when performing different groups of procedures were calculated. Data were analysed using descriptive statistics, ANOVA, t-test and the Pearson coefficient of correlation. RESULTS: The LEP, d lower action value (80 dBA) as set by the Health and Safety Executive (HSE) was met by performing a single revision total knee replacement or a right open ankle debridement. Assuming three procedures are conducted per list, lists consisting of joint replacements (82 dBA) or medium elective procedures (81 dBA) exceed this lower limit. Additionally, lists comprising large and medium bone fractures would be within 1 dB of the limit (79 dBA and 79 dBA, respectively). Soft tissue (74 dBA), arthroscopic (73 dBA), and small bone fracture (71 dBA) procedures had the lowest LEP, d. The greatest contributors to noise levels were surgical instruments. The number of people in the room made a significant difference to noise levels (p = 0.032). CONCLUSIONS: We have established the baseline noise levels in various orthopaedic procedures. Measures should be taken to meet UK regulations. Further research should determine suitable measures for protection from hearing damage for theatre staff and evaluate the risks high noise levels pose to patients.

Therapeutic Function of Liraglutide for Mitigation of Blast-Induced Hearing Damage: An Initial Investigation in Animal Model of Chinchilla.

INTRODUCTION: Auditory injuries induced by repeated exposures to blasts reduce the operational performance capability and the life quality of military personnel. The treatment for blast-induced progressive hearing damage is lacking. We have recently investigated the therapeutic function of liraglutide, a glucagon-like peptide-1 receptor agonist, to mitigate blast-induced hearing damage in the animal model of chinchilla, under different blast intensities, wearing earplugs (EPs) or not during blasts, and drug-treatment plan. The goal of this study was to investigate the therapeutical function of liraglutide by comparing the results obtained under different conditions. MATERIALS AND METHODS: Previous studies on chinchillas from two under-blast ear conditions (EP/open), two blast plans (G1: 6 blasts at 3-5 psi or G2:3 blasts at 15-25 psi), and three treatment plans (blast control, pre-blast drug treatment, and post-blast drug treatment) were summarized. The auditory brainstem response (ABR), distortion product otoacoustic emission (DPOAE), and middle latency response (MLR) recorded within 14 days after the blasts were used. Statistical analysis was performed to evaluate the effect of liraglutide under different conditions. RESULTS: ABR threshold shifts indicated that the conditions of the EP and open ears were substantially different. Results from EP chinchillas indicated that the pre-blast treatment reduced the acute ABR threshold elevation on the day of blasts, and the significance of such an effect increased with the blast level. Liraglutide-treated open chinchillas showed lower ABR threshold shifts at the later stage of the experiment regardless of the blast levels. The DPOAE was less damaged after G2 blasts compared to G1 when pre-blast liraglutide was administrated. Lower post-blast MLR amplitudes were observed in the pre-blast treatment groups. CONCLUSIONS: This study indicated that the liraglutide mitigated the blast-induced auditory injuries. In EP ears, the pre-blast administration of liraglutide reduced the severity of blast-induced acute damage in ears with EP protection, especially under G2. In animals with open ears, the effect of liraglutide on the restoration of hearing increased with time. The liraglutide potentially benefits post-blast hearing through multiple approaches with different mechanics.

Hearing health and noise exposure in population between 18 to 64 years old in Bogotá, Colombia, 2014-2018 / Salud auditiva y exposición a ruido ambiental en población de 18 a 64 años de Bogotá, Colombia, entre el 2014 y el 2018.

Introduction: Hearing health is a public health concern that affects the quality of life and can be disturbed by noise exposure, generating auditory and extra-auditory symptoms. Objective. To identify the hearing health status in adults living in Bogotá and its association with environmental noise exposure and individual and otological factors. Objective: To identify the hearing health status in adults living in Bogotá and its association with environmental noise exposure and individual and otological factors. Materials and methods: We conducted a cross-sectional study using a database with 10,311 records from 2014 to 2018, consigned in a structured survey of noise perception and hearing screening. We performed a descriptive, bivariate, and binary logistic regression analysis. Results: Of the included participants, 35.4% presented hearing impairment. In the perception component, 13.0 % reported not hearing well; 28.8 % had extra-auditory symptoms, 53.3 % informed otological antecedents and 69.0 % presented discomfort due to extramural noise. In the logistic regression, the variables with the highest association for hearing impairment were living in noisy areas (OR = 1.50) (95% CI: 1.34-1.69), being male (OR = 1.85) (95% CI: 1.64-2.09), increasing age (for each year of life, the risk of hearing impairment increased 6%), and having history of extra-auditory symptoms (OR = 1.86) (95% CI: 1.66-2.08). Conclusions: Hearing impairment is multi-causal in the studied population. The factors that promote its prevalence are increasing age, being male, smoking, ototoxic medications, living in areas with high noise exposure, and extra-auditory symptoms.

Introducción. La salud auditiva es un tema de interés en salud pública que afecta la calidad de vida y que puede afectarse por la exposición continua al ruido, un factor de riesgo que genera síntomas auditivos y extraauditivos. Objetivo. Identificar el estado de salud auditiva de adultos que viven en Bogotá, y su asociación con factores de exposición a ruido ambiental, individuales y otológicos. Materiales y métodos. Se realizó un estudio transversal mediante el análisis de una base de datos con 10.311 registros, obtenidos entre los años 2014 y 2018, producto de una encuesta estructurada de percepción de ruido y tamizaje auditivo. Se hizo un análisis descriptivo bivariado y una regresión logística binaria. Resultados. El 35,4 % de los participantes presentó disminución auditiva. En el componente de percepción: 13,0 % refirió no escuchar bien, 28,8 % informó síntomas extraauditivos, 53,3 % tenía antecedentes otológicos, y 69,0 % manifestó molestia por ruido extramural. En la regresión logística, las variables más asociadas con disminución auditiva fueron: de las ambientales, vivir en zonas de mayor ruido (OR = 1,50) (IC95%: 1,34-1,69); de las individuales, ser hombre (OR = 1,85) (IC95%: 1,64-2,09) y la edad (por cada año de vida, el riesgo de disminución auditiva aumentó 6 %); y de las otológicas, tener antecedente de síntomas otológicos (OR = 1,86) (IC95%: 1,66-2,08). Conclusiones. La disminución auditiva es multicausal en la población evaluada. Los factores que aumentan su prevalencia son incremento de la edad, ser hombre, tabaquismo, medicamentos ototóxicos, vivir en zonas de mayor exposición a ruido y presentar síntomas extraauditivos.