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Unlabelled: BACKGROUND Special consideration has recently been given to cepstral analysis with mel-frequency cepstral coefficients (MFCCs). The aim of this study was to assess the applicability of MFCCs in acoustic analysis for diagnosing occupational dysphonia in comparison to subjective and objective parameters of voice evaluation., Materials and Methods: The study comprised 2 groups, one of 55 female teachers (mean age: 45 years) with occupational dysphonia confirmed by videostroboscopy and 40 female controls with normal voice (mean age: 43 years). The acoustic samples involving sustained vowels "a" and four standardized sentences were analyzed by computed analysis of MFCCs. The results were compared to acoustic parameters of jitter and shimmer groups, noise to harmonic ratio, Yanagihara index evaluating the grade of hoarseness, the aerodynamic parameter: maximum phonation time and also subjective parameters: GRBAS perceptual scale and Voice Handicap Index (VHI)., Results: The compared results revealed differences between the study and control groups, significant for MFCC2, MFCC3, MFCC5, MFCC6, MFCC8, MFCC10, particularly for MFCC6 (p < 0.001) and MFCC8 (p < 0.009), which may suggest their clinical applicability. In the study group, MFCC4, MFCC8 and MFCC10 correlated significantly with the major objective parameters of voice assessment. Moreover, MFCC8 coefficient, which in the female teachers correlated with all eight objective parameters, also showed the significant relation with perceptual voice feature A (asthenity) of subjective scale GRBAS, characteristic of weak tired voice., Conclusions: The cepstral analysis with mel frequency cepstral coefficients is a promising tool for evaluating occupational voice disorders, capable of reflecting the perceptual voice features better than other methods of acoustic analysis.

Background: Over recent years numerous papers have stressed that production of voice is subjected to the nonlinear processes, which cause aperiodic vibrations of vocal folds. These vibrations cannot always be characterized by means of conventional acoustic parameters, such as measurements of frequency and amplitude perturbations. Thus, special attention has recently been paid to nonlinear acoustic methods. The aim of this study was to assess the applicability of nonlinear cepstral analysis, including the evaluation of mel cepstral coefficients (MFCC), in diagnosing occupational voice disorders., Material and Methods: The study involved 275 voice samples of pathologic voice (sustained vowel "a" and four standardized sentences) registered in female teachers with the occupation-related benign vocal fold masses (BVFM), such as vocal nodules, polyps, and 200 voice samples of normal voices from the control group of females. The mean age of patients and controls was similar (45 vs. 43 years). Voice samples from both groups were analyzed, including MFCC evaluation., Results: MFCC classification using the Sammon Mapping and Support Vector Machines yielded a considerable accuracy of the test. Voice pathologies were detected in 475 registered voice samples: for vowel "a" with 86% sensitivity and 90% specificity, and for the examined sentences the corresponding values varied between 87% and 100%, respectively., Conclusions: Nonlinear voice analysis with application of mel cepstral coefficients could be a useful and objective tool for confirming occupational-related lesions of the glottis. Further studies addressing this problem are being carried out.

This manuscript presents an overview of current knowledge on the influence of organic solvents on the hearing and balance systems. The authors analyzed--the literature data concerning the results of all human and the most relevant animal studies, published untill 2012. Moreover, the guidelines for occupational medicine specialists were proposed on the basis of literature review and the authors' own scientific experience. The literature data and our studies revealed the increased risk of hearing loss in workers exposed to organic solvents only, and well documented potentiation of harmful effects of combinedexposure to organic solvents and noise. Hearing impairment is mainly observed in high frequencies, but lower frequencies can also be involved (0.5-4 kHz). The impairment induced by exposure to organic solvents is mild, up to several dBs. In the combined exposure to noise and solvents, the noise effect predominates. Organic solvents affect the central pathways of vestibular system although unilateral or bilateral vestibular hypofunction might also be a possible consequence of solvent exposure. Occupational exposure to organic solvents is a risk factor for hearing and balance impairments. Therefore, workers exposed to solvents should be covered by hearing loss prevention programs. Speech in noise test (HINT) and posturography seem to be the most suitable tests for hearing and balance prevention programme for organic solvent exposed workers.

Background: Diagnostic and therapeutic procedures of occupational dysphonia play a major role in voice self-assessment, which is one of the elements of a comprehensive evaluation of voice disorders. The aim of the study was to assess the applicability of the Vocal Tract Discomfort (VTD) scale to monitor the effectiveness of voice rehabilitation and compare the VTD results with objective and instrumental methods of phoniatric diagnosis., Materials and Methods: The study included 55 teachers (mean age, 47.2) with occupational dysphonia. A comprehensive diagnosis took into account self-assessment by VTD scale, phoniatric examination, including laryngovideostroboscopy (LVSS) and objective measurements of the aerodynamic parameter - the maximum phonation time (MPT). After 4 months of intense rehabilitation, post-therapy examination was performed using the methods specified above., Results: After the treatment, a significant improvement was obtained in the subjective symptoms measured on a VTD scale - assessed both for the frequency (p = 0.000) and the severity (p = 0.000) subscales. Positive effects of the therapy were also observed for the parameters evaluated in the phoniatric study (p < 0.01) and laryngovideostroboscopy (p < 0.01). After voice therapy, there was also an improvement in the objective parameter MCF, which was about 5 seconds longer. Studies have shown that the VTD scale is characterized by high reliability - Cronbach's alpha coefficient in the preliminary test was as follows: for the frequency subscale symptoms - 0.826, and severity - 0.845; similarly high reliability was achieved in the control test, 0.908 and 0.923, respectively., Conclusions: Vocal Tract Discomfort scale can be a valuable tool for assessing voice, and can also be used to monitor the effectiveness of therapy of the occupational dysphonia.

Background: Occupational voice disorders are characterized by rich symptomatology, which is dominated by symptoms by the vocal tract discomfort. Therefore, in the management it is important to consider these subjective complaints. The aim of the study was to assess the usefulness of using the vocal tract discomfort scale (VTD) in evaluating the effects of rehabilitation concerning occupational dysphonia., Material and Methods: The study included 55 teachers (mean age: 47.2) with occupational dysphonia diagnosed by means of videostroboscopy. The test battery covered also: voice self-assessment according to voice handicap index (VHI), perceptual GRBAS scale and the new VTD scale. Each subject underwent intensive rehabilitation, including voice training and voice hygiene education. The post-therapy examination was conducted using the above-mentioned methods., Results: Comparing the results obtained in the preliminary and the control test a significant post-therapy improvement (p = 0.000) was discovered in relation to the general outcome of the symptoms in the VTD scale-- assessed both as for the frequency subscale (24.7 points vs. 10 points) and the severity subscale (25.5 points vs. 10 points). A positive significant effect of the treatment was also observed in the voice VHI disability index (p < 0.05) and in perceptual voice evaluation, using the GRBAS scale (p < 0.05). In addition, the study revealed a high coefficient of correlation (r) between the subscales of the VTD, both in the preliminary examination (r = 0.934) and the control one (r = 0.935)., Conclusions: The vocal tract discomfort scale (VTD) seems to be a valuable tool, useful in monitoring the progress in the treatment of occupational voice disorders.

Background: Balance assessment plays an important role in occupational medicine. The diagnosis of patients with balance disturbances is based on a number of laboratory tests, including rotational chair tests, one of the most important. The normative value of kinetic tests greatly depends on movement parameters and laboratory equipment, which vary between diagnostic centers. The aim of the presented paper was to establish normatives for our laboratory and testing methodology in a group of healthy persons., Materials and Methods: The balance examination included 45 healthy persons (21 women and 24 men) aged 20-63 years (mean 38.5 +/- 14.9). The study population underwent very thorough neuro-otological examination, static posturography and VNG tests. The caloric test result was a crucial criterion for inclusion to the group of healthy persons. Rotational tests included: one "burst" test analyzing vestibulo-ocular reflex (VOR) with and without optokinetic stimulation visual vestibular optokinetic reflex (VVOR) and cervico-ocular reflex (COR); three impulse tests and sinusoidal harmonic rotation tests of 0.04, 0.08, 0.1, 0.16, 0.32, and 0.64 Hz., Results: The mean values were: VVOR, 0.9 +/- 0.1; VOR, 0.5 +/- 0.1; and COR, 0.2 +/- 0.1. The mean value of rotational and post-rotational nystagmus induced by sudden chair stop (impulse stimulus) was 9 +/- 7 s, the gain values were 0.4 for sinusoidal tests, in the stimulation range of 0.1-0.32 and 0.5 for 0.64 Hz stimulation. There was no significant linear relationship between age and test parameters except for the test using sinusoidal-decreasing stimulation., Conclusions: These normative values form the base for a closer incorporation of rotational tests in occupational medicine procedures.

Treatment in a health spa with proper infrastructure and professional medical care can provide optimal conditions for intensive voice rehabilitation, especially for people with occupational voice disorders. The most numerous group of people with voice disorders are teachers. In Poland, they have an opportunity to take care of, or regain, their health during a one-year paid leave. The authors describe a multi-specialist model of extensive treatment of voice disorders in a health spa, including holistic and interdisciplinary procedures in occupational dysphonia. Apart from balneotherapy, the spa treatment includes vocal training exercises, relaxation exercises, elements of physiotherapy with the larynx manual therapy and psychological workshops. The voice rehabilitation organized already for two groups of teachers has been received with great satisfaction by this occupational group. The implementation of a model program of extensive treatment of voice disorders in a health spa should become one of the steps aimed at preventing occupational voice diseases.

Objective: It has been shown that oxidative stress plays an important role in development of noise induced hearing loss. Since static magnetic fields (SMF) exposure may alter dynamics of oxidative processes in the tissue, the aim of the study was to assess the influence of SMF on noise-induced alteration in the cochlear level of reactive oxygen species (ROS) and hearing thresholds., Materials and Methods: Auditory brainstem response (ABR), lipid peroxidation (LPO) levels, super-oxide dismutase (SOD) activity and catalase activity were assessed in the cochlea prior to, and at five time-points over two weeks following exposure of C57BL/6 mice to 8h, 119 dB SPL, 4 kHz octave band noise., Results: The ABR indicated no permanent functional damage due to noise exposure either for the 4 kHz and 8 kHz SMF-exposed group or for animals not exposed to SMF. However, significant differences in LPO level, catalase and SOD activity between animals exposed to noise and SMF and those exposed to noise only were observed., Conclusions: The results suggest that SMF causes an increase in ROS level in the cochlea after noise exposure and, at the same time, it speeds up activation of antioxidative enzymes.

Background: The aim of this study was to assess sound exposure and the risk of noise-induced hearing loss (NIHL) in orchestral musicians., Materials and Methods: Questionnaire inquiries and sound pressure level measurements were carried out in 63 musicians. Based on these data the risk assessment of the NIHL was performed according to ISO 1999:1990 (PN-ISO 1999:1990)., Results: The classical orchestral musicians are usually exposed to sound at equivalent continuous A-weighted sound pressure levels of 81-90 dB (10-90th percentile), for 20-48 h (10-90th percentile) per week. Occupational exposures to such sound levels over 40 years of employment cause the risk of hearing impairment (expressed as mean hearing threshold level for 2, 3 and 4 kHz equal or greater than 25 dB) in the range of 13-33% and 9-33% in females and males, respectively. The highest risk is related to playing clarinet (up to 33%), tube (up to 34%), trumpet (up to 37%), trombone (up to 40%), percussion section (up to 41%) and horn (up to 47%). About 46% of respondents noticed hearing impairment. Nearly every fifth musician complained of tinnitus while almost half (48%) of them--of hyperacusis. However, only 14% of musicians declared present or past usage of hearing protective devices (HPDs) while over twice of them (30%) intended to use HPDs in the future.

Background: The aim of this study was to assess the application of Voice Handicap Index (VHI) in the diagnosis of occupational voice disorders in teachers as compared with the dysphonic non-teachers population., Materials and Methods: The subjective assessment of voice by VHI was performed in 105 teachers with dysphonia and 60 dysphonic subjects whose jobs did not involve vocal effort. The control group comprised 65 healthy individuals with normal voice., Results: The results of total VHI score and each of its subscales, functional, emotional and physical, were significantly worse in the study groups (I and II) than in the control group (p < 0.001). The analysis of VHI-score distribution showed that the highest percentage of subjects in groups I and II self-assessed their own voice problems as moderate disability (67% and 57%), while 20% of teachers and 16% of non-teachers reported severe voice disability. All individuals in the control group assessed their voice problems as minor, their results fell within the range of the lowest level of VHI score., Conclusions: This study confirmed that VHI as a tool for self-assessment of voice can significantly contribute to the diagnosis of occupational and non-occupational dysphonia.

Objective: To assess the usefulness of acoustic analysis with vocal loading test for evaluating the treatment outcomes in occupational voice disorders., Methods: Fifty-one female teachers with dysphonia were examined (Voice Handicap Index--VHI, laryngovideostroboscopy and acoustic analysis with vocal loading) before and after treatment. The outcomes of teachers receiving vocal training (group I) were referred to outcomes of group II receiving only voice hygiene instructions., Results: The results of subjective assessment (VHI score) and objective evaluation (acoustic analysis) improved more significantly in group I than in group II. The post-treatment examination revealed a decreased percentage of subjects with deteriorated jitter parameters after vocal loading, particularly in group I., Conclusions: Acoustic analysis with vocal loading test can be a helpful tool in the diagnosis and evaluation of treatment efficacy in occupational dysphonia.

Background: Noise prevailing in the non-occupational environment, such as that experienced in disco or rock concerts may be dangerous to the condition of the human hearing organ. The existing methods for assessing the risk of hearing loss (e.g., specified in ISO 1999:1990) fails to consider the contribution of non-occupational noise to the overall noise exposure. The fact that there is no generally accepted method for assessing the contribution of individual exposures to non-occupational noise to be used in epidemiological studies is one of the reasons that the effect of the quoted ISO procedure is limited. The aim of this study was to develop a method enabling quantitative assessment of the individual level of non-occupational noise exposure and estimation of the exposure uncertainty in large groups of people., Material and Methods: Based on the available literature data and our own results, we established a database on noise levels associated with typical circumstances prevailing in the general environment. A questionnaire was developed to enable collection of data essential for defining individual exposures to non-occupational noise. Using the questionnaire data, a procedure for assessing the level of non-occupational noise exposure was developed and its reliability was determined by assessing the repeatability of the results of two determinations performed every three weeks and comparing the calculated levels of the noise exposures with the true levels., Results: The values of individual non-occupational noise exposure, referred to 8h (LEX, 8h) in the study group of people, using the proposed methods ranged between 69 dB and 80 dB. This method allows to assess individual non-occupational exposures to noise at 1-2 dB error relative to the measured levels. The uncertainty of the method is within 4 dB., Conclusions: The proposed method enables a reliable assessment of non-occupational exposure to non-occupational noise and may be successfully applied in epidemiological studies.

Introduction: Teachers are at risk of developing voice disorders. A clinical battery of vocal function tests should include non-invasive and accurate measurements. The quantitative methods (e.g., voice acoustic analysis) make it possible to objectively evaluate voice efficiency and outcomes of dysphonia treatment., Materials and Methods: To identify possible signs of vocal fatigue, acoustic waveform perturbations during sustained phonation were measured before and after the vocal-loading test in 51 professionally active female teachers with functional voice disorders, using IRIS software. All the participants were also subjected to laryngological/phoniatric examination involving videostroboscopy combined with self-estimation by voice handicap index (VHI)-based scale., Results: The phoniatric examination revealed glottal insufficiency with bowed vocal folds in 35.2%, soft vocal nodules in 31.4%, and hyperfunctional dysphonia with a tendency towards vestibular phonation in 19.6% of the patients. In the VHI scale, 66% of the female teachers estimated their own voice problems as moderate disability. An acoustic analysis performed after the vocal-loading test showed an increased rate of abnormal frequency perturbation parameters (pitch perturbation quotient (Jitter), relative average perturbation (RAP), and pitch period perturbation quotient (PPQ)) compared to the pre-test outcomes. The same was true of pitch-intensity contour of vowel /a:/, an indication of voice instability during sustained phonation., Discussion and Conclusions: The recorded impairments of voice acoustic parameters related to vocal loading provide further evidence of dysphonia. The voice acoustic analysis performed before and after the vocal-loading test can significantly contribute to objective voice examinations useful in diagnosis of dysphonia among teachers.

Background: The aim of this study was to assess the application of Voice Handicap Index (VHI) in the diagnosis of occupational voice disorders in female teachers., Material and Methods: The subjective assessment of voice by VHI was performed in fifty subjects with dysphonia diagnosed in laryngovideostroboscopic examination. The control group comprised 30 women whose jobs did not involve vocal effort., Results: The results of the total VHI score and each of its subscales: functional, emotional and physical was significantly worse in the study group than in controls (p < 0.001). The analysis of VHI-score distribution showed that 68% of female teachers estimated their own voice problems as a moderate disability, while 12% of them reported severe voice disability. However, all non-teachers assessed their voice problems as slight, their results ranged at the lowest level of VHI score., Conclusions: This study confirmed that VHI as a tool for self-assessment of voice can be a significant contribution to the diagnosis of occupational dysphonia.

Background: Ultrasonic noise is defined as broadband noise containing high audible and low ultrasonic frequencies (from 10 kHz to 40 kHz). According to the most advanced knowledge, this type of noise exerts adverse effects on the hearing organ and the vestibular system. The aim of the study was to evaluate exposure to ultrasonic noise in occupational settings and to identify its essential sources., Materials and Methods: The measurements of ultrasonic noise emitted by selected so called low frequency ultrasonic technological devices as well as grinders, circular saws, planers and processes, such as plasma-arc welding and air-acetylene welding, and others, were performed. The study concerned 233 workplaces, where the operators were supposed to be exposed to ultrasonic noise. The measurements were made under typical conditions of work and with reference to Polish standard PN-ISO 9612:2004., Results: The sound pressure levels in the 1/3-octave bands from 10 kHz to 25 kHz (sometimes up to 40 kHz) occurring at workplaces exceeded the admissible values for 8-h exposure (maximum admissible intensity (MAI) values for ultrasonic noise) in all investigated cases of ultrasonic lace sewing machines and cutters as well as in 75% of grinders, 59.5% of ultrasonic welders, 42.9% of ultrasonic washers, and 28.6% of saws and planers. Moreover, in the majority (83.3%) of ultrasonic lace sewing machines and in a large part (33.5%) of welders, the recorded sound levels exceeded the admissible values of maximum sound pressure levels (MAI) in 1/3-octave bands., Conclusions: Our results indicate that ultrasonic welders and lace sewing machines are the major sources of occupational exposure to ultrasonic noise.

Results of standard pure-tone audiometry (PTA) were collected from 25 workers, mainly females, aged 23-58 years, exposed for 2-13 years to ultrasonic noise emitted by ultrasonic welders. Hearing tests were completed by evaluation of exposure to ultrasonic noise. The subjects' actual audiometric hearing threshold levels (HTLs) were compared with theoretical predictions calculated according to ISO 1999:1990. In 60% of cases sound pressure levels in the 10-40 kHz 1/3-octave bands at workstands exceeded Polish exposure limits for ultrasonic noise. Our comparison of predicted and measured HTLs suggests that the ISO 1999:1990 method, intended for audible noise, might also make it possible to predict reliably permanent hearing loss (in the 2000-6000 Hz frequency range) after exposure to ultrasonic noise. No significant progress of hearing impairment (assessed using PTA) in the operators of ultrasonic welders was noted. Nevertheless, further studies on the hearing status of workers exposed to ultrasonic noise are needed.

Background: The aim of this study was to assess the applicability of Voice Handicap Index (VHI) to the evaluation of effectiveness of functional voice disorders treatment in teachers., Material and Methods: The subjects were 45 female teachers with functional dysphonia who evaluated their voice problems according to the subjective VHI scale before and after phoniatric management. Group I (29 patients) were subjected to vocal training, whereas group II (16 patients) received only voice hygiene instructions., Results: The results demonstrated that differences in the mean VHI score before and after phoniatric treatment were significantly higher in group 1 than in group II (p < 0.05). Moreover, the improvement observed in group I applied to each of VHI subscales: functional, emotional and physical, while in group II it applied only to physical subscale., Conclusions: This study confirmed that the VHI test can be a useful method for monitoring phoniatric management efficacy in teacher's dysphonia.

Background: The aim of the study was to assess whether the amended Polish Occupational Diseases Certification Act of 2002 has made an impact on the medico-legal process of the occupational voice diseases certification., Material and Methods: Nationwide reports on the number and types of occupational diseases diagnosed in Poland in 1999-2004, and the medical records of 267 teachers diagnosed for the occupational voice organ disease were analyzed., Results and Conclusions: A 4-fold gradual and continuous reduction (from 3521 to 881 cases) in the number of registered occupational voice diseases was noted in 1999-2004, which was not really associated with the date the amended Act came into force. The patients challenging the first instance refusals issued after 2002 were characterized by significantly worse phoniatric and videostroboscopic indices than those consulted before that date. Before 2002, the percentage of the second instance positive decisions, changing the first instance refusals was over 16%, while after 2002 the corresponding number was only 5%. This indicates that a consensus of decisions issued by the first and second instances has significantly increased since the amended Act came in effect.

Objectives: Individual susceptibility to noise-induced hearing loss (NIHL) depends on the interaction between intrinsic and environmental factors. To proceed with the study on NIHL susceptibility genes an appropriate selection of workers susceptible and resistant to noise is crucial. The aim of the study was to compare four different methods of subject classification by the susceptibility to NIHL in a group of 949 workers of an electric power plant exposed to steady-state noise at the workplace., Materials and Methods: One method based the classification of the workers on the international reference standard ISO 1999:1990; from the entire group of workers, 10% of the subjects with the worst hearing thresholds (HT) in the model were categorized as susceptible to NIHL, whereas 10% of the subjects with the best HT were categorized as resistant to noise. According to three other methods, the entire group of workers was first divided into subgroups by age, duration of employment and the level of noise, and then 10% of the subjects at each HT extreme were selected., Results: The first classification allowed to achieve an excellent separation between HT of the susceptible and resistant subgroups. The susceptible subgroup was significantly younger than the resistant one, showed a shorter duration of employment and a lower level of noise exposure, which is in line with the definition of increased vulnerability to NIHL. The three other methods produced poorer separation of HT with smaller or no gap between HT values in subgroups., Conclusions: The selection of subjects from the entire worker population of a given industry based on the ISO 1999:1990 standard can be regarded as the most reliable method of classification of noise-susceptible and noise-resistant workers to be used in the future genetic studies on NIHL susceptibility genes.

Objectives: The aim of the study was to recommend methods for assessing low frequency noise (LFN) in the occupational environment to prevent annoyance and its effects on work performance. Three different evaluating methods and corresponding admissible values were proposed: (i) method I--frequency analysis in 1/3-octave bands within the range of 10-250 Hz, (ii) method II--consisting in 1/3-octave band measurements and determination of low frequency equivalent-continuous A-weighted sound pressure level (SPL) in the frequency range of 10-250 Hz, and (iii) method III--based on equivalent-continuous A-weighted SPL corrected due to the presence of low frequencies and tonal character of LFN. Separate noise limits were recommended for workplaces in control rooms and office-like areas., Materials and Methods: The proposed criteria were verified in laboratory and field studies. The laboratory study included 55 volunteers, aged 21.8 +/- 2.1 years, with normal hearing (< 25 dB HL). The subjects listened to different noises at A-weighted SPL of 45-65 dB, and evaluated annoyance using a 100-score graphical rating scale. In the field study, 35 male workers, aged 40.1 +/- 7.2 years, exposed to LFN at A-weighted SPL of 48-61 dB, were asked to rate noise annoyance at their workplaces using a similar graphical scale. The subjective ratings of LFNs were compared to objective results from various assessing methods. The relations between annoyance and excesses of proposed limits were analyzed using Pearson's correlation coefficient (r)., Results: Linear relationships between the subjective ratings and results from all proposed exposure criteria were observed (0.550 < or = r < or = 0.673; p < 0.001). In the field conditions, however, the highest correlation coefficient was found for method II (r = 0.673), while during the laboratory study for method I (r = 0.612) and criterion curves based on hearing threshold level (HTL)., Conclusions: All proposed criteria, especially the evaluation method based on the low frequency equivalent-continuous A-weighted sound SPL (method II) as well as the frequency analysis in 1/3-octave bands 10(20)-250 Hz (method I) and criterion curves based on HTL or A-weighting characteristics, seem to be able to quite well predict annoyance experienced from LFN at workplaces.

Background: An assessment of the vocal system, as a part of the medical certification of occupational diseases, should be objective and reliable. Therefore, interest in the method of acoustic voice analysis enabling objective assessment of voice parameters is still growing. The aim of the present study was to evaluate the applicability of acoustic analysis with vocal loading test to the diagnostics of occupational voice disorders., Material and Methods: The results of acoustic voice analysis were compared using IRIS software for phoniatrics, before and after a 30-min vocal loading test in 35 female teachers with diagnosed occupational voice disorders (group I) and in 31 female teachers with functional dysphonia (group II)., Results: In group I, vocal effort produced significant abnormalities in voice acoustic parameters, compared to group II. These included significantly increased mean fundamental frequency (Fo) value (by 11 Hz) and worsened jitter, shimmer and NHR parameters. Also, the percentage of subjects showing abnormalities in voice acoustic analysis was higher in this group., Conclusions: Conducting voice acoustic analysis before and after the vocal loading test makes it possible to objectively confirm irreversible voice impairments in persons with work-related pathologies of the larynx, which is essential for medical certification of occupational voice diseases.

Background: Laryngovideostroboscopy is the method most frequently used in the assessment of voice disorders. However, the employment of quantitative methods, such as voice acoustic analysis, is essential for evaluating the effectiveness of prophylactic and therapeutic activities as well as for objective medical certification of larynx pathologies. The aim of this study was to examine voice acoustic parameters in female teachers with occupational voice diseases., Materials and Methods: Acoustic analysis (IRIS software) was performed in 66 female teachers, including 35 teachers with occupational voice diseases and 31 with functional dysphonia., Results: The teachers with occupational voice diseases presented the lower average fundamental frequency (193 Hz) compared to the group with functional dysphonia (209 Hz) and to the normative value (236 Hz), whereas other acoustic parameters did not differ significantly in both groups., Conclusions: Voice acoustic analysis, when applied separately from vocal loading, cannot be used as a testing method to verify the diagnosis of occupational voice disorders.

Objectives: There is a growing body of data showing that low frequency noise (LFN), defined as broadband noise with dominant content of low frequencies (10-250 Hz) differs in its nature from other environmental noises at comparable levels. The aim of the study was to investigate whether exposure to LFN at levels normally occurring in the industrial control rooms can influence human mental performance (e.g., visual functions, concentration, continuous and selective attention) and subjective well-being., Materials and Methods: The study included 96 female and male volunteers, aged 19-27 years, categorized in terms of sensitivity to LFN. They worked with four standardized psychological tests (Signal Detection, Stroop Color-Word, Comparing of Names, and Continuous Attention) during exposure to LFN or broadband noise without dominant low frequency content (reference noise) at a level of 50 dB(A). Each subject was studied only once at randomly-assigned exposure conditions., Results: In the Comparing of Names Test, the subjects, regardless of the LFN sensitivity, showed tendency to make more errors during exposure to LFN than in the reference noise, and in the Signal Detection Test, they generally reacted faster (had shorter median detection time). In those noise conditions, however, the high-sensitive to LFN subjects, showed tendency to work less precisely (achieved lower number of correct responses in the Signal Detection Test) compared with the low-sensitive ones, while in the reference noise there was no difference related to noise sensitivity. The subjects categorized as high-sensitive to LFN also showed poorer performance than others during exposure to LFN in the Stroop Color-Word Test (a significant interaction between noise and noise sensitivity in case of reading interference index) and in the Continuous Attention Test (a tendency to more erroneous reactions)., Conclusions: These findings suggest that LFN at moderate levels might adversely affect visual functions, concentration, continuous and selective attention, especially in the high-sensitive to LFN subjects.

Background: Noise produced by jet engines may be harmful to aircraft servicing personnel because of high levels of acoustic pressure. The aim of the study was to assess the acoustic environment of persons exposed to jet engine noise and its effect on hearing., Materials and Methods: Noise measurements were performed on three jet engines. During the target practice, the following parameters were measured: equivalent noise, pressure level A, maximum sound pressure level A, and peak sound pressure level C. The spectro-analysis covering the range from 0.1 to 20 kHz was conducted. Hearing was assessed in 50 noise-exposed men, aged 24-51 years (mean age, 35.5 years), using PTA, tympanometry and DPOAE. The control group consisted of 40 non-exposed persons with good hearing condition., Results: Maximum levels of acoustic pressure exceeded Polish standards. Comparison between two groups showed that PTA was higher in the exposed persons by 6.3-6.8 dB on average and DPOAE was reduced in the group exposed to jet engine noise more than it could have been expected., Conclusions: Even during a single test, aircraft technical personnel was exposed to (audible) noise that significantly exceeded admissible values. The reduction in DPOAE values in persons exposed to noise of jet engines was incommensurably higher than changes in PTA.

There is a growing body of data showing that low frequency noise (LFN) defined as broadband noise with dominant content of low frequencies (10-250 Hz) differs in its nature from other noises at comparable levels. The aim of this study was to assess the influence of LFN on human mental performance. Subjects were 193 male paid volunteers. They performed standardized tests: the Signal Detection Test (test I), the Stroop Color-Word Test (test II), and two sub-tests of the General Aptitude Test Battery, i.e. the Math Reasoning Test (test III) and the Comparing of Names Test (test IV). Three different acoustic conditions were used in the experiment the background laboratory noise of about 30 dB(A), LFN and the broadband noise at comparable db(A) levels of 50 dB. The study subjects were assigned randomly to varied experimental conditions. After the test session, the subjects completed a questionnaire aimed at rating the subjective annoyance of exposure conditions during the tasks, and assessing individual sensitivity to noise in general and LFN in particular. The main effects of exposure and/or noise sensitivity on the tests' results or their interaction were found in three of the four tests performed (tests I, II and IV). The tendency towards weaker results in low frequency noise compared to other conditions was observed in persons classified in test II as more sensitive to LFN (higher value of reading interference). The significant effect of both exposure and sensitivity to noise on annoyance rating during test performance was also noted. The annoyance of LFN and reference noise was rated higher than that of background noise. LFN at 50 dB(A) could be perceived as annoying and adversely affecting mental performance (concentration and visual perception), particularly in persons sensitive to LFN.

Objectives: Firearm is a common source of impulse noise that may potentially damage hearing organ. It has been suggested that otoacoustic emissions, particularly transient-evoked otoacoustic emissions (TEOAE), might be more sensitive than pure-tone audiometry (PTA) in the assessment of changes to cochlea caused by noise. The aim of this study was to: (i) evaluate exposure to impulse noise from small-caliber weapons, (ii) compare the post-exposure changes in hearing measured by PTA and TEOAE and correlate them with noise parameters., Materials and Methods: The study included 18 male hunters (group I) and 28 candidate policemen (group II) exposed to impulse noise from small firearms during target practices. Group I was unprotected during shooting, whereas group II used commonly available hearing protectors. PTA and TEOAE were performed before and 2-10 min after shooting. Exposure to impulse noise was evaluated by in situ measurements., Results: Groups I and II were exposed to 3-4 and 4-144 impulses of noise at mean C-weighted peak sound pressure levels of 154 dB and 156 dB, respectively. No post-exposure audiometric threshold shift was observed in group I. Significant reductions of TEOAE levels were found both for the whole response (-2.2 dB SPL) and for 1/2 -octave band responses in the frequency range of 1000-4000 Hz (from -1.6 to -3.0 dB SPL). These changes were not correlated with C-weighted peak sound pressure levels or equivalent-continuous A-weighted sound pressure level. Significant correlation was found for peak sound pressure and maximum sound pressure levels in 1/3-octave bands in the frequency range corresponding with the main part of the acoustic energy of impulses (correlation coefficients r from -0.58 to -0.77, p < 0.05). In group II neither PTA nor TEOAE showed significant hearing impairment after shooting., Conclusions: The results show that even short-term exposure to impulse noise from small-calibre firearms might cause temporary hearing impairment measured by TEOAE. Therefore, the use of earmuffs is strongly recommended, because most of them seem to effectively attenuate impulse noise from small-calibre firearms.