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2001
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tom Vol. 22
213-219
EN
The work presents studied on perception of speech, which is the essence of social efficiency of hearing, depending on degree of noise-induced hearing loss. The applied method consisted in processing verbal tests by a computer system that simulated noise-inducted hearing loss. A group of young people with normal hearing was used in the study and their intelliginility of speech was determined with apprpriately filtered verbal tests. It was found that hearing lodd characteristic of noise-inducted changes consideably impair understanding of speech.
EN
Shooting training is associated with exposure to a considerable amount of unique noise. We wanted to evaluate noise exposure during such training. Our observations especially apply to professional sport shooters, but they are also valid for shooting coaches/instructors. We collected acoustic signals in 10-, 25- and 50-m as well as open-air shooting ranges. The recorded material was analysed with orthogonal, adaptive parameterization by Shur. The mean duration of a single acoustic signal was 250–800 ms with the C-weighted sound peak pressure level of 138.2–165.2 dB. Shooters may be exposed to as many as 600–1350 acoustic impulses during a training unit. The actual load for the hearing organ of a professional shooter or a shooting coach is ~200 000 acoustic stimuli in a year-long training macrocycle. Orthogonal, adaptive parameterization by Shur makes safe scheduling of shooters’ training possible.
EN
The aim of the study was to assess the hearing threshold levels (HTLs) in employees exposed to noise generated by low-frequency ultrasonic technological equipment in comparison with the HTLs of workers exposed to audible noise at the similar A-weighted equivalent-continuous sound pressure level. The study includes measurements of ultrasonic and audible noise at workplaces and hearing tests, i.e. conventional pure-tone audiometry and extended high-frequency audiometry. The study group comprised 90 workers, aged 41.4 ± 10.0 years (mean±SD), exposed for 17.3 ± 9.8 years to noise generated by ultrasonic devices at mean daily noise exposure level (‹LEX,8h›) of 80.6 ± 2.9 dB. The reference group consists of 156 subjects, exposed to industrial noise (without ultrasonic components) at similar A-weighted equivalent-continuous sound pressure level (‹LEX,8h› = 81.8 ± 2.7 dB), adjusted according to age (39.8 ± 7.7 years), gender and job seniority (14.0 ± 7.0 years). This group was selected from database collected in the Nofer Institute of Occupational Medicine. Audiometric hearing threshold levels in the frequency range of 0.5–6 kHz were similar in both groups, but in the frequency range of 8–12.5 kHz they were higher in the group of employees exposed to ultrasonic noise. The findings suggest that differences in the hearing threshold (at high frequencies) in analyzed groups may be due to differences in spectral composition of noise and show the need to continue the undertaken studies.
EN
The aim of this study was to evaluate the hearing status of call centre operators in relation to their noise exposure. Conventional pure-tone audiometry and extended high-frequency audiometry were performed in 49 workers, aged 22-47 years (mean ± SD: 32.0 ± 6.0 years), working in call centre from 1.0 to 16.5 years (mean ± SD: 4.7 ± 2.9 years). Questionnaire inquiry aimed at collecting personal data, the information on communication headset usage habits, self-assessment of hearing ability and identification of risk factors for noise-induced hearing loss were also carried out. Sound pressure levels generated by the communication headset were determined using the artificial ear technique specified in CSA Z107.56-13 (2013) standard. The background noise prevailing in offices was also measured according to PN-N-01307 (1994) and PN-EN ISO 9612 (2011). Personal daily noise exposure levels in call centre operators varied from 66 to 86 dB (10-90th percentile). About half of the study subjects had normal hearing in the standard frequencies (from 250 to 8000 Hz) in both ears, while only 27.1% in the extended high-frequencies (9-16 kHz). Moreover, both high-frequency and speech-frequency hearing losses were observed in less than 10% of audiograms, while the extended high-frequency threshold shift was noted in 37.1% of analysed ears. The hearing threshold levels of call centre operators in the frequency of 0.25-11.2 kHz were higher (worse) than the expected median values for equivalent (due to age and gender) highly screened population specified in ISO 7029 (2017). Furthermore, they were also higher than predicted for 500-4000 Hz according to ISO 1999 (2013) based on the results of noise exposure evaluation.
EN
Tinnitus is defi ned as a perception of sound in the absence of an external acoustic stimulus. Several factors are known to infl uence tinnitus, e.g. hearing loss, noise exposure, age, and hypertension. As only certain individuals develop tinnitus in the presence of the above risks and in approximately 50% of cases tinnitus is not attributed to any particular cause, the question arose whether this inter-individual susceptibility to tinnitus could be explained by the infl uence of genetic factors. Objectives: To test the hypothesis that genetic variability in genes of the potassium recycling pathway is associated with increased susceptibility to tinnitus. Materials and Methods: The study group consisted of 626 subjects exposed to occupational noise (128 with tinnitus and 498 without tinnitus). 99 single nucleotide polymorphisms were investigated in 10 genes involved in the potassium recycling pathway in the inner ear, previously selected as putative noise-induced hearing loss (NIHL) candidate genes. Results: Nominally signifi cant associations were obtained for 2 variants in KCNE1 (potassium voltage-gated channel, Isk-related family, member 1) and SLC12A2 (solute carrier family 12, member 2) genes. The first gene contributed to tinnitus that developed independently of hearing loss, while the second one was associated with increased susceptibility to noise-induced hearing loss. Conclusions: Present fi ndings lend support to the notion of potassium recycling pathway genes as possible risk modifi ers of tinnitus in individuals with and without hearing loss. Due to the lack of replication in other independent populations these results should be seen as suggestive.
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tom Vol. 40, No. 4
503--512
EN
Noise induced hearing loss (NIHL) is a serious occupational related health problem worldwide. The A-wave impulse noise could cause severe hearing loss, and characteristics of such kind of impulse noise in the joint time-frequency (T-F) domain are critical for evaluation of auditory hazard level. This study focuses on the analysis of A-wave impulse noise in the T-F domain using continual wavelet transforms. Three different wavelets, referring to Morlet, Mexican hat, and Meyer wavelets, were investigated and compared based on theoretical analysis and applications to experimental generated A-wave impulse noise signals. The underlying theory of continuous wavelet transform was given and the temporal and spectral resolutions were theoretically analyzed. The main results showed that the Mexican hat wavelet demonstrated significant advantages over the Morlet and Meyer wavelets for the characterization and analysis of the A-wave impulse noise. The results of this study provide useful information for applying wavelet transform on signal processing of the A-wave impulse noise.
EN
Objectives The aim of this study was to assess hearing of music students in relation to their exposure to excessive sounds. Material and Methods Standard pure-tone audiometry (PTA) was performed in 168 music students, aged 22.5±2.5 years. The control group included 67 subjects, non-music students and non-musicians, aged 22.8±3.3 years. Data on the study subjects’ musical experience, instruments in use, time of weekly practice and additional risk factors for noise-induced hearing loss (NIHL) were identified by means of a questionnaire survey. Sound pressure levels produced by various groups of instruments during solo and group playing were also measured and analyzed. The music students’ audiometric hearing threshold levels (HTLs) were compared with the theoretical predictions calculated according to the International Organization for Standardization standard ISO 1999:2013. Results It was estimated that the music students were exposed for 27.1±14.3 h/week to sounds at the A-weighted equivalent-continuous sound pressure level of 89.9±6.0 dB. There were no significant differences in HTLs between the music students and the control group in the frequency range of 4000–8000 Hz. Furthermore, in each group HTLs in the frequency range 1000–8000 Hz did not exceed 20 dB HL in 83% of the examined ears. Nevertheless, high frequency notched audiograms typical of the noise-induced hearing loss were found in 13.4% and 9% of the musicians and non-musicians, respectively. The odds ratio (OR) of notching in the music students increased significantly along with higher sound pressure levels (OR = 1.07, 95% confidence interval (CI): 1.014–1.13, p < 0.05). The students’ HTLs were worse (higher) than those of a highly screened non-noise-exposed population. Moreover, their hearing loss was less severe than that expected from sound exposure for frequencies of 3000 Hz and 4000 Hz, and it was more severe in the case of frequency of 6000 Hz. Conclusions The results confirm the need for further studies and development of a hearing conservation program for music students. Int J Occup Med Environ Health 2017;30(1):55–75
EN
Objectives The objective of this study was to assess the hearing of employees using communication headsets with regard to their exposure to noise. Material and Methods The study group comprised 213 employees, including 21 workers of the furniture industry, 15 court transcribers and 177 call center operators, aged 19–55 years, working with headsets for a period of up to 25 years. All the participants underwent a standard puretone audiometry, extended high-frequency audiometry (EHFA) as well as transient-evoked otoacoustic emissions (TEOAEs) and distortion-product otoacoustic emissions (DPOAEs). Noise exposure from headsets was evaluated using the microphone in a real ear technique according to PN-EN ISO 11904-1:2008. Results Personal daily noise exposure levels ranged 57–96 dB and exceeded 85 dB only in 1.4% of the call center operators. Forty-two percent of the participants had bilateral normal hearing in the standard frequency range of 250–8000 Hz, and 33% in the extended highfrequency range of 9–16 kHz. It was found that DPOAEs were present bilaterally in 59% of the participants. Reproducibility of TEOAE at >70% and signal-to-noise ratio at >6 was exhibited by 42% and 17% of them, respectively. The 3 subgroups of workers differed in age, gender, noise exposure and type of headsets in use. However, after adjusting for age and gender, significant differences between these subgroups in terms of hearing were mostly visible in EHFA. A significant impact of age, gender, daily noise exposure level and current job tenure on hearing tests results was also noted among the call center operators and the transcribers. The most pronounced were the effects of age and gender, whereas the impact of the daily noise exposure level was less evident. Conclusions It seems that EHFA is useful for recognizing early signs of noise-induced hearing loss among communication headset users. However, further studies are needed before any firm conclusions concerning the risk of hearing impairment due to the use of such devices can be drawn.
EN
ObjectivesThe aim of the study was to evaluate the hearing status of operators of low-frequency ultrasonic devices compared to employees exposed to audible noise at a similar A-weighted sound pressure level (SPL) but without ultrasonic components.Material and MethodsStandard pure-tone audiometry, extended high-frequency audiometry (EHFA), transient-evoked otoacoustic emissions (TEOAE), and distortion-product otoacoustic emissions (DPOAE), as well as questionnaire surveys were conducted among 148 subjects, aged 43.1±10.8 years, working as ultrasonic device operators for 18.7±10.6 years. Their exposure to noise within the ultrasonic and audible frequency range was also evaluated. The control group comprised 168 workers, adjusted according to gender, age (±2 years), tenure (±2 years), and the 8-hour daily noise exposure level (LEX,8h) of ±2 dB.ResultsThe ultrasonic device operators and the control group were exposed to audible noise at LEX,8h of 80.8±3.9 dB and 79.1±3.4, respectively. The Polish maximum admissible intensity (MAI) values for audible noise were exceeded in 16.8% of the ultrasonic device operators, while 91.2% of them were exposed to ultrasonic noise at SPL>MAI values. There were no significant differences between the groups in terms of the hearing threshold levels (HTLs) up to 3 kHz, while the ultrasonic device operators exhibited significantly higher (worse) HTLs, as compared to the control group, in the range of 4–14 kHz. The results of the DPOAE and TEOAE testing also indicated worse hearing among the ultrasonic device operators. However, the differences between the groups were more pronounced in the case of EHFA and DPOAEs.ConclusionsThe outcomes of all hearing tests consistently indicated worse hearing among the ultrasonic device operators as compared to the control group. Both EHFA and DPOAE seem to be useful tools for recognizing early signs of hearing loss among ultrasonic device operators.
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Objectives It has been shown that monitoring temporary threshold shift (TTS) after exposure to noise may have a predictive value for susceptibility of developing permanent noise-induced hearing loss. The aim of this study is to present the assumptions of the TTS predictive model after its verification in normal hearing subjects along with demonstrating the usage of this model for the purposes of public health policy. Material and Methods The existing computational predictive TTS models were adapted and validated in a group of 18 bartenders exposed to noise at the workplace. The performance of adapted TTS predictive model was assessed by receiver operating characteristic (ROC) analysis. The demonstration example of the usage of this model for estimating the risk of TTS in general unscreened population after exposure to loud music in discotheque bars or music clubs is provided. Results The adapted TTS predictive model shows a satisfactory agreement in distributions of actual and predicted TTS values and good correlations between these values in examined bartenders measured at 4 kHz, and as a mean at speech frequencies (0.5–4 kHz). An optimal cut-off level for recognizing the TTS events, ca. 75% of young people (aged ca. 35 years) may experience TTS >5 dB, while <10% may exhibit TTS of 15–18 dB. Conclusions The final TTS predictive model proposed in this study needs to be validated in larger groups of subjects exposed to noise. Actual prediction of TTS episodes in general populations may become a helpful tool in creating the hearing protection public health policy. Int J Occup Med Environ Health. 2023;36(1):125–38
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51%
EN
The aim of this study was to evaluate the hearing status in young adults using portable audio players (PAPs) in relation to their listening habits. The study included 58 subjects, aged 22.8±2.8 years, non-occupationally exposed to noise. Questionnaire inquiry aimed at collecting personal data, the information on PAPs usage habits, self-assessment of hearing status and identification of risk factors for noise-induced hearing loss (NIHL) were performed in study subjects. Hearing tests included pure-tone audiometry (PTA) and transient-evoked optoacoustic emission (TEOAE). All subjects were PAPs users. Depending on listening habits they were divided into the subgroups of “frequent” users (>1 h/day) and “non-frequent” users (≤1 h/day). There were no significant differences between subgroups in prevalence of NIHL risk factors and self-assessment of hearing status. However, frequent users more often complained of tinnitus and hyperacusis. Majority (81.9 %) of participants had normal hearing. Nevertheless, 6.9 % of audiograms showed high-frequency notches typical for NIHL. Both, the PTA and TEOAE indicated worse hearing in non-frequent users compared to frequent users. No significant differences in prevalence of high-frequency notches between subgroups were noted. The outcomes do not support some previous studies results that the excessive exposure to music listened through PAPs might result in accelerating of development of NIHL loss in young adults.
EN
In noisy workrooms, exposure conditions such as noise level, exposure duration and use of hearing protection devices are contributory factors to hearing loss. The aim of this study was to determine the effect of exposure conditions on the risk of hearing loss using the Cox model. Seventy workers, employed in a press workshop, were selected to study their hearing threshold using an audiometric test. Their noise exposure histories also were analyzed. The results of the Cox model showed that the job type, smoking and the use of protection devices were effective to induce hearing loss. The relative risk of hearing loss in smokers was 1.1 times of non-smokers The relative risk of hearing loss in workers with the intermittent use of protection devices was 3.3 times those who used these devices continuously. The Cox model could analyze the effect of exposure conditions on hearing loss and provides useful information for managers in order to improve hearing conservation programs.
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