Noise Induced Hearing Loss Research Papers (original) (raw)

2025, Occupational Hygiene and Health Promotion

Introduction: Today, it is well-established that, in addition to hearing loss, noise affects the natural physiological functions of the body. The aim of this study was to determine the effect of noise on hearing loss and blood pressure in workers of a steel industry in southwest of Iran. Methods: This study was performed on 54 steel workers. Dosimetry was performed using TES 1358 sound meter and Beurer BC16 blood pressure monitor, respectively. Statistical analysis was done using SPSS 24 software at the significant level of 0.05. Results: There was a significant relationship between hearing loss and sound pressure level in each of the case and control groups (P< 0.05). Despite the significant relationship between hearing loss and age, (P˂0.05), there was no significant relationship between the work experience variable and hearing loss (P> 0.05). Age and work experience had a significant relationship with hearing loss at some frequencies under the study (P˂0.05). There was also...

2025, International Journal of Audiology

The purpose of the present study was to investigate possible associations between college students' attitudes, risk-taking behaviour related to noisy activities, and hearing problems such as threshold shifts or self-experienced hearing symptoms. The sample included 258 students aged between 17 and 21 enrolled at the University of Pennsylvania, USA. A questionnaire measuring attitudes towards noise, use of hearing protection, and selfreported hearing symptoms was distributed among the students. After completing the questionnaire a hearing screening, including pure-tone audiometry and tympanometry, was conducted. The result revealed that 26% had thresholds poorer than the screening level of 20 dBHL. Attitudes were significantly related to self-experienced hearing symptoms, but not to threshold shifts. Attitudes and noise sensitivity was, significantly related to use of hearing protection. Hearing protection use was found in activities such as using firearms, mowing lawns, and when using noisy tools but was less reported for concerts and discotheques. It can be concluded that the young adults in this study expose themselves to hearing risks, since the use of hearing protection is in general very low.

2025

This study aimed to analyze Noise Induced Hearing Loss among the staff of a public state university in the north of Paraná. The research is characterized as a descriptive transversal study, undertaken between June and July 2014. The data were obtained through documental analysis. A total of 131 workers participated in the research, with a mean age of 53 years old, each one undertaking an average of three audiometric examinations. It was observed that in the last audiometric examination undertaken, 30% of the sample group presented some form of hearing loss, representing an increase of 2.3 times, or 230%, of persons with this health problem, in comparison with the reference audiometric examination. These results indicate that it is not enough to undertake occasional audiometric examinations, but that actions for promoting health and preventing harm to health are also necessary, including the worker in the planning and control of her auditory health.

2025

Introduccion: La Hipoacusia Neurosensorial Inducida por Ruido representa uno de los problemas de salud ocupacional mas prevalentes dejando graves secuelas en el organo de la audicion. Con el proposito de buscar soluciones a esta problematica, se planteo determinar el comportamiento de la susceptibilidad auditiva y el de la audiometria tonal en trabajadores expuestos a ruido industrial. Metodologia: Estudio descriptivo, retrospectivo, realizado en 52 trabajadores de una empresa manufacturera de Cali, Colombia. Las variables analizadas fueron: caracteristicas sociodemograficas y ocupacionales, susceptibilidad auditiva (Test de Wilson) y los resultados de las ultimas tres evaluaciones audiologicas realizadas a los trabajadores. Resultados: El 40% de la muestra labora en el area de mayor presion sonora (92,9 dB) de la empresa. Los antecedentes relacionados con exposicion a ruido mas prevalentes fueron: exposicion a ruido extralaboral y consumo de alcohol. Segun el test de Wilson solo 3 ...

2025, Scandinavian Journal of Work, Environment & Health

Cross-sectional evaluation of an internet-based hearing screening test in an occupational setting by Sheikh Rashid M, Leensen MCJ, de Laat JAPM, Dreschler WA This cross-sectional study evaluates an online-based speech-in-noise test specifically designed for the detection of noise-induced hearing loss, in a representative population of noise-exposed employees. The test appears to be suitable for the screening of high-frequency losses, with sensitivity and specificity values of >80%. This study describes translational research for the application of this test in an occupational setting.

2025, Global Journal of Health Science

INTRODUCTION: Hearing protection devices are one of the primary noise reduction tools in developing countries. This study is intended to produce and apply acrylonitrile butadiene styrene (ABS)/clay nanocomposites to fabricate a laboratory single cup earmuffs and then compare it with double cup and single cup pure ABS earmuffs in terms of noise attenuation performance and comfort. In addition, the noise attenuation performance of single cup pure ABS earmuffs is compared with double cup pure ABS earmuffs. METHODS: ABS/nanoclay filament was fabricated using a twin screw extruder. A three dimensional (3D) printing machine and a 3D model of earcup, designed by solid work software, were applied to print single and double cup earmuffs using ABS/nanoclay composite and pure ABS filaments. Finally, using an acoustic test fixture, objective noise attenuation test was performed on three different types of earmuffs, including with and without nano material and a secondary cup. Moreover, earmuffs...

2025, International Journal of Audiology

Objective: Recently, the Digit Triplet test was shown to be a sensitive speech-in-noise test for early high-frequency hearing loss in noise-exposed workers. This study investigates if a further improvement is achieved when using a closed set of consonant-vowel-consonant (CVC) speech items with the same vowel, and/or a low-pass (LP) filtered version of the standard speech-shaped noise. Design: Speech reception thresholds in noise were gathered for the Digit Triplet, CVC, and CVC_LP test and compared to the high-frequency pure-tone average (PTA). Study sample: 118 noiseexposed workers showing a wide range of high-frequency hearing losses. Results: For the 84 Dutchspeaking participants, the CVC test showed an increased measurement error and a decreased between-subject variation, leading to a weaker correlation with the PTA 2,3,4,6 (R=0.64) and thus a lower sensitivity compared to the Digit Triplet test (R=0.86). However, the use of LP-filtered noise resulted in a sensitivity improvement (R=0.79 versus R=0.64) due to the large increase in betweensubject spread. Similar trends were found for the 34 French-speaking workers. Conclusions: Using CVC words with the same vowel could not increase the sensitivity to detect isolated high-frequency hearing loss. With LP-filtered noise, test sensitivity improved, but it did not surpass the original Digit Triplet test.

2025, Ear and Hearing

Objective: Hearing screening in occupational medicine is generally based on pure-tone threshold audiometry. However, reliable and valid thresholds can only be obtained in a sound-proof room, using a high-quality, well-calibrated audiometer, and by a well-trained administrator. Thresholds also need to be determined for several audiometric frequencies. This makes the test timeconsuming and expensive, which is not ideal for the screening of large populations. A speech-innoise test, by contrast, does not have the above-mentioned requirements. Because it can be implemented as a quick automated self-test, possibly over the Internet, a speech-in-noise test is highly advantageous for screening purposes. However, its sensitivity for (isolated) high-frequency hearing loss, as typically seen in noise-exposed listeners, was unclear up to present. In this study, the authors investigated the sensitivity and specificity of the Digit Triplet speech-in-noise test for detecting and monitoring (early-stage) high-frequency hearing loss, and its similarity across two different language versions. Design: 118 noise-exposed workers, representing a wide range from no to severe high-frequency hearing loss, completed the French or Dutch version of the broadband Digit Triplet self-test in an office-like room. Pure-tone thresholds, collected by a professional audiologist in favorable settings, served as the reference. Results: The 84 Dutch-speaking participants showed a very strong linear relation between the reference and the Digit Triplet test, with the pure-tone average at 2, 3, 4, and 6 kHz as a strong predictor (R=0.86) for the speech reception threshold. The sensitivity and specificity to detect mild high-frequency hearing loss were 92% (61/66) and 89% (16/18), respectively. The area under the receiver operating characteristic (ROC) curve was very high (≥ 0.91) for several degrees of high-frequency hearing loss. With a withinsubject standard deviation of only 0.8 dB, the Digit Triplet test also had a low measurement error. The results of the 34 French-speaking subjects showed a highly similar trend. Conclusions: The Digit Triplet test proves to have a high sensitivity and specificity for detecting different degrees of highfrequency hearing loss. Given its ease of use, this test is very suitable for screening purposes in occupational medicine, and potentially for the screening of adolescents at risk of a recreational noise-induced hearing loss.

2025, JOURNAL OF ENVIRONMENTAL ENGINEERING AND LANDSCAPE MANAGEMENT

This study focuses on occupational hazards and the determination of risk levels derived from them. Indoor climate, noise, and dust are examined. An approach with numerical criteria is offered to assess these occupational hazards in manufacturing using a simple/flexible risk assessment method. Practical examples and the results of measurements of occupational hazards in five industries (mechanical, printing, wood, plastic and clothing industries) in Estonia are presented. Noise, as the most obvious health hazard, is analysed in depth, and the risk for noise‐induced hearing loss is estimated. The overall purpose of the paper is to draw attention to the importance of measurements of occupational hazards in industry and to act as a reminder of a number of issues of practical relevance to effective workplace risk assessment from which employees, employers, occupational hygienists and physicians as well as authorities can benefit today and in the future. Santrauka Analizuojami profesiniai...

2025

The trials were carried out in a pasta factory in Bari Province and confirmed that the existent studies regarding health risks in the pasta production sector can be used as the starting point. However it is necessary to make a specific analysis of the parameters which constitute risk factors, using scientific apparatus. Evaluation of the risks deriving from noise involved a problem of interpretation. The differences found between data obtained with a phonometer and data obtained with a dosimeter may be in contrast, and the dosimeter data can be a source of concern for the workers' health and therefore for their employers who are responsible for health and safety. In actual fact, when the reality of the situation was examined, it was seen that different plant operations involve workers' movements which can stress the microphones differently from acoustic pressure. Therefore, the noise levels which are actually indicative of the situation in the workplace are the phonometer data. However, these too were quite high: daily exposure levels of over 80 dB(A), 85 dB(A) and 90 dB(A) in one case, while the impulsive noise levels were always lower Lpk=112 dB(C). Evaluation of the risk from exposure to particulate matter showed concentrations of inhalable particulate matter PM 10 which were constantly below the level of TLV-TWA = 0.5 mg/m 3 adopted by the ACGIH as the maximum inhalable dose in eight hours of work. This shows the efficiency of the dust extractor system, which the firm recently upgraded. However, we looked at preventive measures which consisted of: -working regulation defined by applying industrial health and safety procedures ; -correct and continuous maintenance of the extractor system; -identification of workers who are more susceptible to respiratory diseases -mostly caused by semolinas powder -even when exposed to levels below TLW. This study has further confirmed that the risk evaluation is not an exact science; in that it does not consist only of technical and mechanical factors, but needs also to consider the many factors connected to workers' interaction with the workplace.

2025

Recent years the noise is one of the leading pollutants in working and living environment. Although in some cases the noise levels do not exceed proposed levels, people often have the opposite impression. While for the most activities noise regulation exists, for public events this is not the case. There are certain guidelines, however established levels differ from country to country. In order to determine the noise level during public events the equivalent level of noise was measured at one public event on which approximately 50,000 people was present. The results show significantly high levels of noise, especially during rock concert and firework, when certain protective measures should be implemented.

2025, Global Institute for Research and Innovation

Noise pollution has always been a prevalent case in industrial environment, yet there has never been a cohesive assertion on the actual effect of these noise exposures on the blood pressure. Many occupational studies have allied exposure to noise in working environment to a number of physiological and psychological responses like secretion of adrenaline and cortisol needed to adjust the body function but in-return may result to an increase in blood pressure. On the contrary, some researchers have emphatically disagreed with the findings by pointing-out that different individuals are likely to exhibit different noise excitations. This research was to investigate whether there is noise pollution in sawmills and also to examine if there is any significant blood pressure changes as a result of the noise pollution. The research was carried out in phases. In the first phase of the study, a sound level meter was used to determine the ambient noise levels in the sawmills. These measured noise levels were used to calculate workers exposure dosage. In the subsequent phase of the study, a structured health and life style questionnaire was used as exclusion criteria for the selection of the eventual subjects that was tested with automatic sphygmomanometer for blood pressure difference. The research population comprises a population of male and female(n=101) in the sawmill environment, who had been exposed to high level of noise from one year and above and whose activities are within the measured noise level distance. The blood pressure and pulse pressure was measured at regular two-minute intervals before, and after prolonged period of exposure to high (fluctuating) noise level. Result was analyzed by SPSS-17 package using student t-test. The subjects selected for control group were six volunteer students (male), aged 25-32 years and were exposed to high level of (fluctuating) noise, and later exposed to experimental conditions, without production of noise. The result of the study have established that noise pollution was prevalent in these sawmills, and has a significant effects on the blood pressure. However, these effects as regards to increase or decrease depends on some other un-captured factors since individual noise appraisal and societal appreciation of the activities generating the noise have also a notable effect on whether the effect would be tending towards a decrease or increase. In conclusion, the noise exposure dosage of these sawmill workers exceeds the permissible exposure limit as prescribed by the occupational safety and health administration. In addition, prolonged exposure to high (fluctuating) noise levels may be a possible influence on the blood pressure changes.

2025, Acta Oto-Laryngologica

Sensorineural hearing loss following a variety of acoustic trauma, including middle ear surgery, is well known. Current literature, which points to the deleterious in uence of noise on the inner ear during surgery, has yet to assess the in uence of vibration generated by the burr. The purpose of the study reported here was to establish an animal model that mimics drilling and can be used to explore methods of hearing loss prevention and treatment. A specially developed electromagnetic vibrator was calibrated and used in 59 guinea pigs to induce hearing loss. Both young and old guinea pigs were used. The bony external ear canal of guinea pigs were exposed to vibration or sound of varying duration and intensity. The vibration of the temporal bone and noise level in the middle ear were measured. Electrocochleography was recorded to evaluate the hearing loss. Among the young animals, 90% developed a signi cant threshold shift (TS \ 20 dB), when vibrated with 250 Hz at an intensity of 6.2 m:s 2 for 15 min. An average of 42 dB TS was observed. With 10 min exposure 63% showed a TS. The older animals vibrated for 5 min developed the same TS (mean TS 34 dB) as the young animals when vibrated for 10 min. The vibration-induced TS showed no recovery within 3 days of observation. In the contralateral ear 4 out of 5 animals showed TS\ 20 dB. When exposed to sound levels exceeding the vibration-generated sound in the middle ear (119 dB at 250 Hz) only 2 out of 11 animals (18%) showed TS. The frequency of TS and level of TS were signi cantly greater in the vibrated animals than in sound-only exposed animals (pB 0.01). The degree of vibration-induced TS in the present animal model could be controlled by vibration intensity and duration. The older animals were more susceptible to vibration-induced inner-ear damage than younger animals. This model will be used in further studies to nd methods for prevention and treatment of hearing loss during ear surgery.

2025, International Journal of Molecular Sciences

Noise exposure represents the second most common cause of acquired sensorineural hearing loss and we observed that tumor necrosis factor α (TNFα) was involved in this context. The effect of Tnfα gene silencing on the expression profile related to the TNFα metabolic pathway in an experimental model of noise-induced hearing loss had not previously been studied. Methods: Single ears of Wistar rats were pretreated with Tnfα small interfering RNA (siRNA) by trans-tympanic administration 24 h before they were exposed to white noise (120 dBSPL for three hours). After 24 h of noise exposure, we analyzed the electrophysiological threshold and the amplitude of waves I, II, III, and IV in the auditory brain response click. In addition, qRT-PCR was performed to evaluate the TNFα metabolic pathway in the ears submitted or not to gene silencing. Results: Preservation of the electrophysiological threshold and the amplitude of waves was observed in the ears submitted to gene silencing compared to t...

2025

75 non-pilots, divided into five age groups, having age range between 20 and 44 years, were selected randomly. Pure tone audiometry (PTA) of the subjects was carried out, means were calculated separately for both the ears. RESULTS: All 75 (100%) pilots used helmets with integrated earmuffs, while 12 (16%) non-pilots used earmuffs and 63 (84%) used earplugs as personal ear protectors. All the 75 (100%) pilots used ear protectors and their hearing thresholds were recorded.

2025

Sound which is disagreeable, discordant or which interferes with the reception of wanted sound are regarded as noise. Therefore, any sound that is unpleasant, unwanted and disturbing are categorised as noise. However, the effect of noise on individual at different level varies due to individual tolerance even though a high level of noise or sound is still unaccepted to the human psychological and physiological composition. Mining deals with the excavation of rock and mineral deposit which are located near surface and involves drilling, blasting, haulage and transportation and processing operations which are sources of noise. Their effects on mine workers’ health cannot be underestimated. Physical measurement of noise level was carried out with the aid of Extech Model 407750 Digital Sound Level Meter. Noise measurements were carried out during drilling with hand held Jack-hammers and milling operations at the processing plants. Noise measurement procedures involved repetitive direct ...

2025, PubMed

Introduction: Exposure to hazardous noise induces one of the forms of acquired and preventable hearing loss that is noise-induced hearing loss (NIHL). Considering oxidative stress as the main mechanism of NIHL, it is possible that myricetin can protect NIHL by its antioxidant effect. Therefore, the present study aimed to investigate the preventive effect of myricetin on NIHL. Materials and methods: A total of 21 Wistar rats were randomly divided into five groups, namely (1) noise exposure only as control group, (2) noise exposure with the vehicle of myricetin as solvent group, (3) noise exposure with myricetin 5 mg/kg as myricetin 5 mg group, (4) noise exposure with myricetin 10 mg/kg as myricetin 10 mg group, (5) and non-exposed as sham group. The hearing status of each animal was assessed by Distortion Product Otoacoustic Emissions. Results: The levels of response amplitude decreased after the exposure to noise in all groups and returned to a higher level after 14 days of noise abstinence at most frequencies; however, the difference was not significant in the myricetin-receiving or control groups. Conclusion: The results of this study showed that two doses of myricetin (5 and 10 mg/kg) administered intraperitoneally could not significantly decrease transient or permanent threshold shifts in rats exposed to loud noise.

2025, Brazilian Journal of Otorhinolaryngology

2025, Rev Cefac

Projeto acadêmico sem fins lucrativos desenvolvido no âmbito da iniciativa Acesso Aberto 386 Izumi R, Mitre EI, Duarte MLM RESUMO Objetivo: pesquisar o que existe na literatura sobre o efeito das Vibrações de Corpo Inteiro (VCI) na audição dos trabalhadores expostos a esse risco, presente em muitos ambientes ocupacionais. Métodos: pesquisa bibliográfica em sites de busca de artigos e periódicos como Pubmed, Periódicos Capes e Lilacs, além de consultas em bibliotecas. Resultados: estudos analisados apresentaram, de forma geral, grande concordância no que diz respeito ao efeito das VCI na audição. Pode-se afirmar que a VCI atua de forma sinérgica com o ruído, ou seja, potencializa os danos auditivos causados pelo ruído. Conclusões: a pesquisa envolvendo perdas auditivas ocupacionais é muito rica e deve ser mais aprofundada. A associação de riscos ocupacionais é muito comum e diversa. Combinações de ruído com produtos químicos, vibrações ou calor se apresentaram danosas à audição segundo a literatura. Uma vez que na maioria dos postos de trabalho reais existe associação entre ruído e VCI (o objetivo deste trabalho), isto se torna um fato preocupante a ser pesquisado em maiores detalhes.

2025, Cad Saude Publica

The objective of this study was to verify an association between noise-induced hearing loss (NIHL) and tinnitus in workers exposed to occupational noise. Workers with a history of work noise exposure who attended two audiology outpatient clinics were interviewed and evaluated. The statistical association between NIHL and tinnitus was evaluated using an adjusted linear regression model, with tinnitus as the dependent variable and NIHL, classified into six levels, as the independent variable, with age and length of noise exposure as covariates. Data were collected from 284 workers between April and October, 2003, in Bauru, São Paulo State, Brazil. Tinnitus was observed to increase with the progression of auditory damage, controlled by age and length of noise exposure. These results suggest that investment in hearing conservation programs is needed, especially for source noise emission control and for intervention in hearing loss progression that is caused by noise exposure, in order to maintain auditory health and reduce the associated symptoms.

2025

The medial olivocochlear (MOC) efferent feedback circuit projecting to the cochlear outer hair cells (OHCs) confers protection from noise-induced hearing loss and is generally thought to be driven by inner hair cell (IHC) - type I spiral ganglion afferent (SGN) input. Knockout of the Prph gene (PrphKO) encoding the peripherin type III intermediate filament disrupted the OHC - type II SGN innervation and virtually eliminated MOC – mediated contralateral suppression from noise delivered to the opposite ear, measured as a reduction in cubic distortion product otoacoustic emissions. Electrical stimulation of the MOC pathway elicited contralateral suppression indistinguishable between wildtype (WT) and PrphKO mice, indicating that the loss of contralateral suppression was not due to disruption of the efferent arm of the circuit; IHC – type I SGN input was also normal, based on auditory brainstem responses. High-intensity, broadband noise (108 dB SPL, 1 hour) produced permanent hearing lo...

2025, Purinergic Signalling

A major component of slowly reversible hearing loss which develops with sustained exposure to noise has been attributed to release of ATP in the cochlea activating P2X 2 receptor (P2X 2 R) type ATP-gated ion channels. This purinergic humoral adaptation is thought to enable the highly sensitive hearing organ to maintain function with loud sound, protecting the ear from acoustic overstimulation. In the study that established this hearing adaptation mechanism as reported by Housley et al. (Proc Natl Acad Sci U S A 110:7494-7499, 2013), the activation kinetics were determined in mice from auditory brainstem response (ABR) threshold shifts with sustained noise presentation at time points beyond 10 min. The present study was designed to achieve finer resolution of the onset kinetics of purinergic hearing adaptation, and included the use of cubic (2f 1 -f 2 ) distortion product otoacoustic emissions (DPOAEs) to probe whether the active mechanical outer hair cell 'cochlear amplifier' contributed to this process. We show that the ABR and DPOAE threshold shifts were largely complete within the first 7.5 min of moderate broadband noise (85 dB SPL) in wildtype C57Bl/6J mice. The ABR and DPOAE adaptation rates were both best fitted by a single exponential function with ~3 min time constants. ABR and DPOAE threshold shifts with this noise were minimal in mice null for the P2rx2 gene encoding the P2X 2 R. The findings demonstrate a considerably faster purinergic hearing adaptation to noise than previously appreciated. Moreover, they strongly implicate the outer hair cell as the site of action, as the DPOAEs stem from active cochlear electromotility.

2025, Hearing Research

Exposure to intense sound or noise can result in purely temporary threshold shift (TTS), or leave a residual permanent threshold shift (PTS) along with alterations in growth functions of auditory nerve output. Recent research has revealed a number of mechanisms that contribute to noiseinduced hearing loss (NIHL). The principle cause of NIHL is damage to cochlear hair cells and associated synaptopathy. Contributions to TTS include reversible damage to hair cell (HC) stereocilia or synapses, while moderate TTS reflects protective purinergic hearing adaptation. PTS represents permanent damage to or loss of HCs and synapses. While the substrates of HC damage are complex, they include the accumulation of reactive oxygen species and the active stimulation of intracellular stress pathways, leading to programmed and/or necrotic cell death. Permanent damage to cochlear neurons can also contribute to the effects of NIHL, in addition to HC damage. These mechanisms have translational potential for pharmacological intervention and provide multiple opportunities to prevent HC damage or to rescue HCs and spiral ganglion neurons that have suffered injury. This paper reviews advances in our understanding of cellular mechanisms that contribute to NIHL and their potential for therapeutic manipulation.

2025, BioMed Research International

We have previously shown that adenosine amine congener (ADAC), a selective A1adenosine receptor agonist, can ameliorate noise- and cisplatin-induced cochlear injury. Here we demonstrate the dose-dependent rescue effects of ADAC on noise-induced cochlear injury in a rat model and establish the time window for treatment.Methods. ADAC (25–300 μg/kg) was administered intraperitoneally to Wistar rats (8–10 weeks old) at intervals (6–72 hours) after exposure to traumatic noise (8–16 kHz, 110 dB sound pressure level, 2 hours). Hearing sensitivity was assessed using auditory brainstem responses (ABR) before and 12 days after noise exposure. Pharmacokinetic studies investigated ADAC concentrations in plasma after systemic (intravenous) administration.Results. ADAC was most effective in the first 24 hours after noise exposure at doses>50 μg/kg, providing up to 21 dB protection (averaged across 8–28 kHz). Pharmacokinetic studies demonstrated a short (5 min) half-life of ADAC in plasma after...

2025, Proceedings of the National Academy of Sciences

The sense of hearing is remarkable for its auditory dynamic range, which spans more than 10 12 in acoustic intensity. The mechanisms that enable the cochlea to transduce high sound levels without damage are of key interest, particularly with regard to the broad impact of industrial, military, and recreational auditory overstimulation on hearing disability. We show that ATP-gated ion channels assembled from P2X 2 receptor subunits in the cochlea are necessary for the development of temporary threshold shift (TTS), evident in auditory brainstem response recordings as sound levels rise. In mice null for the P2RX2 gene (encoding the P2X 2 receptor subunit), sustained 85-dB noise failed to elicit the TTS that wild-type (WT) mice developed. ATP released from the tissues of the cochlear partition with elevation of sound levels likely activates the broadly distributed P2X 2 receptors on epithelial cells lining the endolymphatic compartment. This purinergic signaling is supported by signific...

2025, Proceedings of the National Academy of Sciences

Age-related hearing loss and noise-induced hearing loss are major causes of human morbidity. Here we used genetics and functional studies to show that a shared cause of these disorders may be loss of function of the ATP-gated P2X 2 receptor (ligand-gated ion channel, purinergic receptor 2) that is expressed in sensory and supporting cells of the cochlea. Genomic analysis of dominantly inherited, progressive sensorineural hearing loss DFNA41 in a six-generation kindred revealed a rare heterozygous allele, P2RX2 c.178G > T (p.V60L), at chr12:133,196,029, which cosegregated with fully penetrant hearing loss in the index family, and also appeared in a second family with the same phenotype. The mutation was absent from more than 7,000 controls. P2RX2 p.V60L abolishes two hallmark features of P2X 2 receptors: ATP-evoked inward current response and ATP-stimulated macropore permeability, measured as loss of ATP-activated FM1-43 fluorescence labeling. Coexpression of mutant and WT P2X 2 r...

2025

Noise-induced hearing loss (NIHL) is a major occupational health problem that can be prevented through the use of hearing protection devices (HPDs). The objective of the paper was the accomplishment of a survey ofNoise-induced hearing loss in a small city. A case study design was utilized to identify, describe and evaluate noise sources, exposures and control strategies used by those "high", "moderate" and "low" risk industry sectors in relation to exposure to noise. The present study involved the pretest data collected as a part of an ongoing hearing protection and cardiovascular disease prevention intervention study.It was found that of the "high risk" industry sectors surveyed, most had mean and median sound levels that were at or above L Aeq.8hr 85dB.Engineering and construction businesses had the greatest percentage of employees exposed to noise levels above 85dB L Aeq.8hr (85%, 83%). Noise exposure in these industries were some of highest recorded in this study. (Median L Aeq.8hr range 83.5-95dB).From the findings of the present study, it would appear that lack of prioritization of noise exposure and perceptions of the seriousness of NIHL over other things affecting the business are key cultural barriers facing effective noise management at workplaces in developing regions.

2025, Revista Médica del hospital General de México

Introduction: Auditory Brainstem Response, also known as short-latency auditory evoked potentials (SLAEP) is a useful tool for performing auditory evaluations in children and difficult to test patients. Different types of stimuli have been described to elicit the auditory response including Click and CE-chirps among others. Objective: The objective the study is to compare the auditory brainstem response thresholds obtained with Click and CE-Chirp stimuli and to describe if there is a difference in the correction factor for the auditory brainstem hearing threshold between the two stimuli. Material and methods: A retrospective, cross-sectional, observational, comparative, and descriptive study was carried out. The patients' records who, as a diagnostic protocol, had been evaluated with auditory brainstem response with both Click and CE-Chirp, were analyzed. 38 ears were reviewed with both CE-Chirp and Click recordings. The mean and standard deviations between the electrophysiological hearing thresholds of both stimuli were calculated. A student's t-test was performed between the means of the hearing threshold. The correction factor for CE-Chirp was calculated. Results: The means of the electrophysiological hearing threshold obtained with Click stimulus were of 30.26 dBnHL and with CE-Chirp of 23.21 dBnHL. There is a significant difference between the hearing thresholds obtained with both stimuli with p = 0.000. Conclusions: The threshold difference between CE-Chirp and Click was 6.57 dB, and the thresholds obtained with CE-Chirp are lower than with Click. Therefore, thresholds between 20 dBnHL and 25 dBNHL with CE Chirp should be considered normal, unlike the Click that is universally accepted as normal with 30 dBnHL or less.

2025, Journal of Laryngology and Otology

Background: Disorders of balance often pose a diagnostic conundrum for clinicians, and a multitude of investigations have emerged over the years. Vestibular evoked myogenic potential testing is a diagnostic tool which can be used to assess vestibular function. Over recent years, extensive study has begun to establish a broader clinical role for vestibular evoked myogenic potential testing. Objectives: To provide an overview of vestibular evoked myogenic potential testing, and to present the evidence for its clinical application. Review type: Structured literature search according to evidence-based medicine guidelines, performed between November 2008 and April 2009. No restrictions were applied to the dates searched. Conclusion: The benefits of vestibular evoked myogenic potential testing have already been established as regards the diagnosis and monitoring of several clinical conditions. Researchers continue to delve deeper into potential new clinical applications, with early results suggesting promising future developments.

2025, The Journal of Laryngology & Otology

Background:Disorders of balance often pose a diagnostic conundrum for clinicians, and a multitude of investigations have emerged over the years. Vestibular evoked myogenic potential testing is a diagnostic tool which can be used to assess vestibular function. Over recent years, extensive study has begun to establish a broader clinical role for vestibular evoked myogenic potential testing.Objectives:To provide an overview of vestibular evoked myogenic potential testing, and to present the evidence for its clinical application.Review type:Structured literature search according to evidence-based medicine guidelines, performed between November 2008 and April 2009. No restrictions were applied to the dates searched.Conclusion:The benefits of vestibular evoked myogenic potential testing have already been established as regards the diagnosis and monitoring of several clinical conditions. Researchers continue to delve deeper into potential new clinical applications, with early results sugge...

2025

pins removed and holes bored in the sides of the chambers are as effective as operational guns. Local gun dealers or others may donate old firearms and a gunsmith can remove the firing pins. Actual firearms, whether operational or dummy, provide a more authentic experience of firearm handling in the field. Participants should be instructed to assume they have the proper firearm for each secnario (i.e., shotgun, light rifle, large bore rifle) regardless of what they are carrying. Deer stand: A stand can be simulated with a stepladder. If a real stand is used it is best not to set it at full height, but to leave it low for safety and control and to allow everyone to see and hear the discussion. Existing stands also can be used. Check them first (just as you should before hunting) for damage, weak points, wasps and other animals. Camouflage: Camouflage clothing can be put on mannequins or hung on a clothes hanger in a tree. Camouflage pieces do not have to match. Large pieces of camouflage cloth can be used as demonstration blinds. Mannequins: Retail stores often can provide old mannequins, but they may be bulky and heavy. Lightweight mannequins can be made with chicken wire or camouflage clothing stuffed with newspaper or hay. Clothes also can be hung in trees and brush. Using live "mannequins" can be very dramatic when they respond to the student hunters' actions. Vehicle: An actual vehicle can be used, or one can be simulated with chairs. Fence: Take precautions if an existing fence is used, especially barbed wire. Using existing fence is discouraged when there is the possibility of damaging the fence or injuring a student. Create a fence crossing with two t-posts, stakes, existing trees, smooth wire, rope, or flagging tape. Even a broomstick across chairs works well. Dummy Ammunition: Dummy ammunition looks and feels like live ammunition, but lacks powder and primer. It can be obtained from the state hunter education staff and possibly from hunter education area chiefs. This adds to the realism of firearm handling because students can choose the proper ammunition for the gun and practice handling and loading it properly. Hunter orange vests and caps: These items are used to identify hunters and to illustrate laws and safety practices related to the use of hunter orange. "No Trespassing" and/or "No Hunting Without Permission" sign/Purple Paint Wildlife identification materials: Shed antlers, tanned hides, feathers from game birds, tracks and other materials can be used to teach wildlife identification. Clay pigeon thrower: Use this to simulate flushing quail or dove. Binoculars: These are part of a responsible hunter's equipment. Use them instead of a rifle scope to identify game. Asking local landowners and businesses to donate items is a great way to get them involved and keep them informed of local hunter education events. Do not be afraid to ask for help. Your excitement and enthusiasm are contagious.

2025, Facultad Nacional De Salud Publica

La investigación fue financiada por el Ministerio de la Protección Social, entidad que tiene los derechos de propiedad sobre la misma y ha concedido autorización a la Revista para su publicación. Se reproduce aquí lo relacionado con la... more

2025

O objetivo do estudo foi estimar a prevalência de sintomas auditivos e vestibulares em trabalhadores expostos a ruído ocupacional. Foram analisados os prontuários de 175 trabalhadores com perda auditiva induzida por ruído, atendidos em um centro de referência de saúde ocupacional de Campinas, SP, de 1997 a 2003. As variáveis estudadas foram freqüência dos sintomas de hipoacusia, zumbido e vertigem. As associações com idade, tempo de exposição ao ruído e limiares auditivos tonais foram analisadas utilizando-se os testes estatísticos qui-quadrado e exato de Fisher. Foram relatados hipoacusia em 74% dos casos, zumbidos em 81% e vertigem em 13,2 %. Verifi cou-se associação entre hipoacusia e idade, tempo de exposição ao ruído e limiares auditivos tonais e entre vertigem e tempo de exposição ao ruído, não sendo encontradas outras associações signifi cativas.

2025, International Journal of Otolaryngology and Head & Neck Surgery

Objective: To determine the audiometric profile of deafness in our practice. Materials and Methods: Longitudinal prospective study was conducted out in the ENT department and cervicofacial surgery of Gabriel Toure University Hospital in Bamako, we made an exhaustive sampling of all the patients who consulted for hearing loss, tinnitus, vertigo, hiring report, medical expertise and whose deafness was confirmed to tonal audiometry with an age greater than or equal to 15 years. It was spread over 10 months (June 2016 to March 2017). A total of 200 patients were collected. Exclusion criteria were all patients under 15 years of age as well as deafness related to earwax or foreign bodies, and refusal to participate in the study Results: During our study period, 6055 outpatients were admitted out of which 734 patients underwent audiometric testing and 200 patients (3.30%) met our criteria. The male sex was the most represented with a rate of 60%. The sex ratio was 1.5 or 3 men for 2 women. The 15 to 25 age group was the most represented at 37.5%. The average age was 37.18 years old with extremes ranging from 15 to 83 years old. Pupils/students were the most represented with a rate of 29.5%, followed by housewives in 23%, farmers in 10.5% and military in 10%. As antecedent 26% of our patients had a chronic otitis media (OMC), against 23% who had no antecedent otological and 17% had a traumatic antecedent. Bilateral deafness was the most common with a rate of 64.5%. The mode of progressive appearance was the most frequent in 74.5%. As functional signs 46.22% of our patients had a hearing loss associated with tinnitus. Otoscopic examination was pathological in 34.5% of our patients. Mixed deafness was the most common in 43.35%, followed by perception deafness in 32.19% and transmission

2025

Noise exposure leads to hearing loss in industrial workers due to release of superoxide anions which damage cochlear epithelium in the ear. These free radicals are regulated by superoxide dismutase 2 (SOD2) and polymorphism in this gene may abet in predisposition to noise induced hearing loss (NIHL). The current study describes prevalence of polymorphism at two different loci of SOD2 gene in NIHL patients and association of smoking habit with NIHL. PCR-SSCP analysis of polymorphic sites revealed mutation in NIHL patients. Results showed that IVS1+8A/G and IVS3-23T/G SOD2 polymorphisms are associated with NIHL (p< 0.05, CI 95%) irrespective of smoking habit (p > 0.01). It is intended that SOD2 polymorphism plays a significant diagnostic role in determining susceptibility of NIHL in Pakistani industry employees.

2025, American Journal of Industrial Medicine

Background It has been suggested that extended high-frequency audiometry (EHFA) might be more sensitive than conventional audiometry in detecting early signs of hearing impairment. However, this technique has not been adequately tested in an occupational environment. We therefore investigated the usefulness of this method in noise-exposed workers. Methods We compared conventional frequency audiometry (0.25-8 kHz) and EHFA (9-18 kHz) in 184 noise-exposed and 98 non-noise-exposed workers. Results Both methods showed significantly higher threshold levels (P < 0.05) in noiseexposed workers for most of the tested frequencies; however, the differences were more marked for EHFA, especially in young exposed workers. Significant differences in the EHF range were detected also in the subgroup of noise-exposed workers with normal findings at conventional audiometry. Stepwise regression analysis showed that in 21-to 40-year-old workers the noise effect was largely predominant at both conventional audiometry and EHFA, whereas in older subjects the noise effect was predominant up to 6 kHz frequency, the effect of age being significantly greater at higher frequencies. Conclusions These data indicate that EHFA is more sensitive than conventional audiometry in detecting noise induced hearing loss. However, hearing loss in the EHFrange seems an agedependent phenomenon with progression into the lower speech range frequencies with increasing age. These changes seem to be accentuated in the early years by noise exposure, suggesting that EHFA could represent a useful preventive measure in young exposed workers.

2025, The Journal of International Advanced Otology

To evaluate the protective effect of betahistine on noise-induced hearing loss (NIHL) using scanning electron microscopy (SEM) and distortion product otoacoustic emission (DPOAE). A total of 8 adult albino guinea pigs were used in this study (study group: n=4 and control group: n=4). DPOAE measurements of both groups were performed before the procedure. Two hours before noise exposure, 0.9% NaCl solution was injected perorally to the control group and betahistine was administered through a peroral catheter to the study group. Both groups were then exposed to 105-dB sound pressure level (SPL) 4-kHz frequency-based narrow-band noise for 2 h per day for 5 days. DPOAE measurements were performed again on the 6th day and cochleae were dissected and examined by SEM on the 7 th day. Regarding the results of DPOAE, NIHL was observed in both groups on the 6th day (p<0.05). Loss, flattening, and fusion, which are findings of permanent hearing loss, were determined in the stereocilia of the inner and outer hair cells by SEM. These findings were evaluated as signs of permanent increase in the threshold. When DPOAE measurements and SEM results were evaluated in the study group, no significant difference was observed in NIHL compared with the control group (p>0.05). In our study, it was observed that simultaneous administration of betahistine during noise had no protective effect on permanent increase in the threshold. However, further studies on noise and long-term use of betahistine can be performed.

2025, AIMS Public Health

Background: It has been proposed that Noise-induced hearing loss is a complex disease that is combination of environmental and genetic factors. There are inconsistent results concerning the association between variation in glutathione S-transferase (GST) genetic polymorphisms (GSTT1 rs1049055 and GSTM1 rs10712361) and susceptibility to Noise-induced hearing loss. Objective: This study was designed to assess the association between GST gene polymorphism and Noise-induced hearing loss among noise-exposed workers. Methods: In a case-control study, male workers from tile and ceramic factories were selected randomly. Subjects were classified into two groups according to the result of audiometry: 73 subjects showed Noise-induced hearing loss which was considered in the case group and 87 subjects without hearing loss was enrolled in the control group. The GSTT1 and GSTM1 polymorphism of both groups were assessed by multiplex polymerase chain reaction. Results: Null GSTT1 and GSTM1 genotypes were more frequent in case group but no significant statistical difference was seen in case and control groups. No significant link between GSTT1 and GSTM1 genotypes was found. Conclusion: This study suggests that the genetic variability of GSTT1 and GSTM1 has no effect on susceptibility to noise induced hearing loss.

2025, Brazilian Journal of Otorhinolaryngology

The clinical evaluation of subjects with occupational noise exposure has been difficult due to the discrepancy between auditory complaints and auditory test results. This study aimed to evaluate the contralateral acoustic reflex thresholds of workers exposed to high levels of noise, and to compare these results to the subjects' auditory complaints. Methods: This clinical retrospective study evaluated 364 workers between 1998 and 2005; their contralateral acoustic reflexes were compared to auditory complaints, age, and noise exposure time by chi-squared, Fisher's, and Spearman's tests. Results: The workers' age ranged from 18 to 50 years (mean = 39.6), and noise exposure time from one to 38 years (mean = 17.3). We found that 15.1% (55) of the workers had bilateral hearing loss, 38.5% (140) had bilateral tinnitus, 52.8% (192) had abnormal sensitivity to loud sounds, and 47.2% (172) had speech recognition impairment. The variables hearing loss, speech recognition impairment, tinnitus, age group, and noise exposure time did not show relationship with acoustic reflex thresholds; however, all complaints demonstrated a statistically significant relationship with Metz recruitment at 3,000 and 4,000 Hz bilaterally Conclusion: There was no significance relationship between auditory complaints and acoustic reflexes.

2025, BMC Neuroscience

Background: Notch signaling plays a crucial role in the fate determination of cochlear progenitor cells, hair cells, and supporting cells in the developing cochlea. Recent studies have demonstrated the temporal activation of Notch signaling in damaged mature cochleae, and have demonstrated the induction of new hair cells by pharmacologically inhibiting Notch signaling. The present study aimed to illustrate the feasibility of pharmacologically inhibiting Notch signaling by using a gamma-secretase inhibitor for treating sensorineural hearing loss. Results: The effect of the sustained local delivery of MDL28170, a gamma-secretase inhibitor, on hearing and hair cell induction was tested in a guinea pig model with noise-induced hearing loss. MDL28170 was directly delivered into the cochlear fluids via a micro-osmotic pump. Drug application was initiated 7 days after noise exposure. Measurements of auditory brainstem responses revealed better hearing in the MDL28170-treated animals than in the vehicle controls. Histological analysis demonstrated a higher number of outer hair cells in the MDL28170-treated cochleae than the vehicle-treated cochleae. Conclusion: These findings strongly suggest that local sustained delivery of a gamma-secretase inhibitor into the cochlea could be a novel strategy for treating acute hearing loss that is refractory to conventional treatment.

2025, Bangladesh Journal of Otorhinolaryngology

Noise is one of the common physical environmental hazard in the workplace. A study was carried out in a textile industry at Gazipur from July 2004 to December 2004 to find out the prevalence, types and severity of hearing loss among the workers. The sample size was 97 and the total number of workers was 1900. Out of 97 sample, 26 workers were having noise induced hearing loss (NIHL). The incidence of NIHL was 20.59% in workers aged less than 35 years and 41.38%. in workers aged above 35 years Among the departments of factory, highest noise level was in generator department (96-100 dB). In generator department, 46.67% workers had the hearing loss. Overall, the prevalence of NIHL among textile workers of the study place was 33.46%. Key words: Noise, NIHL, industrial workers.DOI: 10.3329/bjo.v14i2.3279 Bangladesh J of Otorhinolaryngology 2008; 14(2) : 39-45

2025, Scientific reports

Excessive occupational exposure to noise results in a well-recognized occupational hearing loss which is prevalent in many workplaces and now it is taken as a global problem. Therefore, this study aims to assess the prevalence of noise-induced hearing loss and associated factors among workers in the Bishoftu Central Air Base in Ethiopia. An institutional-based cross-sectional study was conducted among 260 central air base workers through face-to-face interviews, an environment noise survey, and an audiometric test for data collection. Data were entered by Epi-data version 3.1 and SPSS was used to analyze the data. Finally, a statistical analysis such as descriptive and binary logistic regression analysis was applied. A P-value < 0.05 at 95% CI was considered statistically significant. The overall prevalence of noise-induced hearing loss and hearing impairments was 24.6 and 30.9%, respectively. The highest prevalence of noise-induced hearing loss was recorded for workers who were exposed to noise levels greater than 90 dBA. Out of 132 workers exposed to the average noise level of 75 dB A, only 5% of workers were affected with noise-induced hearing loss, while 128 workers exposed to an average noise level equal to or greater than 90 dB A, 19.6% of workers were identified with noise-induced hearing loss. Regarding sex, around 21.9% of male workers were identified with noiseinduced hearing loss. Workers who were exposed to a high noise level workplace previously or before the Central Air Base workplace were five times (AOR = 5.0, 95% CI 1.74-14.36) more likely affected by noise-induced hearing loss than those workers not previously exposed. Those workers who were exposed to greater or equal to 90dBA noise level were 4.98 times (AOR = 4.98, 95% CI 2.59-9.58) more likely to be exposed to noise-induced levels than those who were exposed to less than 90dBA noise level. Moreover, male air base workers were 3.5 times more likely exposed to hearing impairment than female workers (AOR = 3.5, 95% CI 1.01-12.0). This study identified that the prevalence of noiseinduced hearing loss and hearing impairments was significantly high. So implementation of a hearing conservation program, giving noise education, and supplying adequate hearing protective devices (HPDs) are essentials.

2025, Noise & Health

Objective: The objective was to describe the speech intelligibility in noise test results among Dutch teenagers and young adults aged 12-24 years, using a national online speech reception threshold (SRT) test, the Earcheck. A secondary objective was to assess the effect of age and gender on speech intelligibility in noise. Design: Cross-sectional SRT data were collected over a 5-year period (2010-2014), from participants of Earcheck. Regression analyses were performed, with SRT as the dependent variable, and age and gender as explaining variables. To crossvalidate the model, data from 12-to 24-year olds from the same test distributed by a hearing aid dispenser (Hoorscan) were used. Results: In total, 96,803 valid test results were analyzed. The mean SRT score was -18.3 dB signal-to-noise ratio (SNR) (standard deviation (SD) = 3.7). Twenty-five percent of the scores was rated as insufficient or poor. SRT performance significantly improved with increasing age for teenagers aged 12-18 years by 0.49 dB SNR per age-year. A smaller age-effect (0.09 dB SNR per age-year) was found for young adults aged 19-24 years. Small differences between male and female users were found. Conclusion: Earcheck generated large quantities of national SRT data. The data implied that a substantial number of users of Earcheck may have some difficulty in understanding speech in noise. Furthermore, the results of this study showed an effect of gender and age on SRT performance, suggesting an ongoing maturation of speech-in-noise performance into late adolescence. This suggests the use of age-dependent reference values, but for this purpose, more research is required.

2025, Journal of electrical and electronic systems research

2025, Journal of Evidence Based Medicine and Healthcare

Occupational settings and transport is the prominent sources of noise that affect health. Noise-Induced Hearing Loss (NIHL) is sensory neural hearing loss due to exposure to intense impulse or continuous sound. Exposure to noise can be occupational or non-occupational. The audiologic profile of NIHL is the presence of sensorineural hearing loss that is most pronounced in the high-frequency region between 3,000 Hz and 6,000 Hz of the audiogram and the greatest amount of hearing loss is typically around the 4,000-Hz region (i.e. 4,000 Hz dip). The main causes of hearing loss resulting in deafness in adults in India are excessive noise, age and ear infection. Although, occupational hearing loss is a well-recognized occupational condition arising from industries or occupations with exposure to high noise levels (e.g., airline crew), 2 it has not been fully evaluated in occupations where the risk is not so overt such as the police force. Police officers are potentially exposed to multiple sources of noise including vehicle horns, gunfire, barking from police dog and traffic noise. The aim of the study is to study the incidence of noise-induced hearing loss amongst traffic police personnel who came for master health checkup. A total of 812 constables were examined. All individuals underwent a complete general, systemic and ENT examination to detect any obvious pathology, which may result in hearing loss. A detailed history was taken regarding the number of years of service in traffic branch, place of duty, past history of ear disease or intake of ototoxic drugs. Subjects suffering from preexisting ear disease such as CSO, OME, otosclerosis and suffering from URI has been excluded. Policemen suffering from hypertension and diabetes were also excluded. Remaining 774 was included in the study. This study was approved by the institutional ethical committee, Government Theni Medical College. Written consent was obtained from all the policemen participating in study. All the individuals were subjected to pure tone audiometry to detect the degree and type of hearing loss. The subjects in the study had undergone pre-enrolment medical examination and had normal hearing at the time of enrolment. Settings and Design-A study was undertaken by the Department of ENT, Government Theni Medical College, Theni, during June 3, 2015, to July 21, 2015. The subjects for this study were the police personnel who came for master health checkup. A significant number of personnel were detected to be suffering from NIHL. No significant relationships was found between hearing loss and the age group of the individuals. There was an even distribution of hearing impaired individuals in all age groups. Those personnel who had less than 2 years' service in the traffic branch had slightly less (60.3%) incidence of hearing loss as compared to others who had a higher incidence of approximately 85%. The hearing loss was mild in case of inspectors and more than 40 dB in constables. It was unilateral in (30.8%) individuals and bilateral in (69.2%) individuals. These types of audiometric pattern were encountered-1) Descending curve; 2) Hearing loss in frequency beyond 4000 Hz; 3) A pattern of audiometric notching was seen at 4000 Hz or 6000 Hz. A significantly large number of subjects in this study showed sensorineural hearing loss, which was of moderate-to-severe intensity in as many as of the individuals. It was bilateral in majority of the subjects and was directly related to the duration of exposure. In view of the high incidence of acoustic damage, a number of preventive measures were suggested like rotation of beat of traffic personnel between high-and low-noise intensity areas, use of personal ear protectors like ear defenders or ear muffs and creation of awareness among exposed individuals about the hazards of noise pollution.

2025, Noise and Health

Adolescent exposure to loud music has become a social and health problem whose study demands a holistic approach. The aims of the current study are: (1) To detect early noise-induced hearing loss among adolescents and establish its relationship with their participation in musical recreational activities and (2) to determine sound immission levels in nightclubs and personal music players (PMPs). The participants consisted in 172 14-15 years old adolescents from a technical high school. Conventional and extended high frequency audiometry, transient evoked otoacoustic emissions and questionnaire on recreational habits were administered. Hearing threshold levels (HTLs) were classifi ed as: normal (Group 1), slightly shifted (Group 2), and signifi cantly shifted (Group 3). The musical general exposure (MGE), from participation in recreational musical activities, was categorized in low, moderate, and high exposure. The results revealed an increase of HTL in Group 2 compared with Group 1 (P < 0.01), in Group 3 compared with Group 2 (P < 0.05) only in extended high frequency range, in Group 3 compared with Group 1 (P < 0.01). Besides, a decrease in mean global amplitude, reproducibility and in frequencies amplitude in Group 2 compared with Group 1 (P < 0.05) and in Group 3 compared with Group 1 (P < 0.05). A signifi cant difference (P < 0.05) was found in Group 1's HTL between low and high exposure, showing higher HTL in high exposure. The sound immission measured in nightclubs (107.8-112.2) dBA and PMPs (82.9-104.6) dBA revealed sound levels risky for hearing health according to exposure times. It demonstrates the need to implement preventive and hearing health promoting actions in adolescents.

2025

This study aims to elucidate the potential protective effects of Pycnogenol ® against noise-induced hearing (NIHL) loss in a rat model. This study employed a randomized controlled design to investigate the potential protective effects of Pycnogenol ® against NIHL in a rat model. Twenty-five male Wistar albino rats were randomly assigned to 5 groups (n = 5 per group): a control group receiving saline administration, a noise exposure group, a noise+saline receiving group, only Pycnogenol ® receiving group, and finally, a Pycnogenol ® treatment group receiving daily oral administration of Pycnogenol ® at 40 mg/kg/day via gavage for 7 days following noise exposure. All groups were subjected to auditory brainstem response assessments at 4 time points: pre-exposure (baseline), post-exposure day 1, day 7, and day 21. Both noise exposure and the Pycnogenol ® treatment groups were exposed to 4 kHz narrowband noise at 120 dB SPL for 4 hours. Following sacrifice, histological and immunohistochemical evaluations were conducted on cochlear tissues. Statistical analyses were performed using SPSS software version 25 to determine significant differences between groups and across time points. Outcome of this research shows that the auditory brainstem response thresholds and cochlear morphology between the experimental and control groups are significantly different from each other, suggesting that Pycnogenol ® may have the potential to prevent NIHL loss in rats. CONCLUSION: Pycnogenol® shows potential in protecting against NIHL. However, further research, particularly at the molecular level, is necessary to better understand its therapeutic mechanisms and its specific impact on auditory metabolic processes.

2025, The FASEB Journal

Betaine homocysteine S-methyltransferases (BHMTs) are methionine cycle enzymes that remethylate homocysteine, hence their malfunction leads to hyperhomocysteinemia. Epidemiological and experimental studies have revealed a correlation between hyperhomocysteinemia and hearing loss. Here, we have studied the expression of methionine cycle genes in the mouse cochlea and the impact of knocking out the Bhmt gene in the auditory receptor. We evaluated age-related changes in mouse hearing by recording auditory brainstem responses and following exposure to noise. Also we measured cochlear cytoarchitecture, gene expression by RNA-arrays and RT-qPCR, and metabolite levels in liver and plasma by HPLC. Our results indicate that there is an age-dependent strain-specific expression of methionine cycle genes in the mouse cochlea and a further regulation during the response to noise damage. Loss of Bhmt did not cause an evident impact in the hearing acuity of young mice, but it produced higher threshold shifts and poorer recovery following noise challenge. Hearing loss was associated with increased cochlear injury, altered expression of cochlear methionine cycle genes and hyperhomocysteinemia. Our results suggest that BHMT plays a central role in the homeostasis of cochlear methionine metabolism and that Bhmt2 upregulation could carry out a compensatory role in cochlear protection against noise injury in the absence of BHMT.