[Attenuation of ultrasonic noise in the 10-16 kHz frequency range by earplugs]. / Tlumienie halasu ultradzwiekowego w zakresie czestotliwosci 10­16 kHz przez wkladki przeciwhalasowe.

BACKGROUND: The aim of the study was to determine attenuation of earplugs for ultrasonic noise in the frequency range of 10-16 kHz. MATERIAL AND METHODS: The attenuation of earplugs in 1/3-octave-bands with the centre frequencies of 10 kHz, 12.5 kHz, and 16 kHz using the REAT (real-ear attenuation at threshold) method based on the measurements of hearing threshold of subjects. The study was carried out for 29 models of earplugs commonly used in the industry designed by various manufacturers, including 13 models of foam earplugs, 10 models of flanged earplugs, 5 models of headband earplugs and one model of no-roll earplugs. RESULTS: The values of the measured attenuation of earplugs are in the range 12.9-33.2 dB for the 10 kHz frequency band, 22.8-35.2 dB for the 12.5 kHz frequency band and 29.5-37.2 dB for the 16 kHz frequency band. The attenuation of earplugs in the frequency range 10-16 kHz has higher values (statistically significant changes) for foam earplugs than flanged earplugs (p = 0.0003 vs. p = 0.0006) or headband earplugs (p = 0.0002 vs. p = 0.04). CONCLUSIONS: The tests indicated that there is no uniform relation between the sound attenuation in the frequencies range of 10-16 kH and the catalogue H parameter (high-frequency attenuation value) of earplugs. Therefore, it is not possible to easily predict the attenuation of ultrasonic noise in the frequency range of 10-16 kHz using the sound attenuation data for the normally considered frequency range (up to 8 kHz). Med Pr 2018;69(4):395-402.

[Attenuation of earmuffs used simultaneously with respiratory protective devices]. / Tlumienie dzwieku nauszników przeciwhalasowych stosowanych jednoczesnie ze sprzetem ochrony ukladu oddechowego.

BACKGROUND: In the work environment, apart from the noise, employees may be exposed to other harmful factors. Therefore, they wear hearing protectors and other personal protective equipment. The aim of the study was to determine whether simultaneous use of earmuffs and respiratory protective devices affects the attenuation of earmuffs. MATERIAL AND METHODS: The study was conducted in laboratory conditions using the subjective REAT (Real Ear Attenuation at Threshold) and objective MIRE (Microphone in Real Ear) methods. The REAT method was used to measure sound attenuation of earmuffs, while MIRE was used to determine changes in attenuation of earmuffs due to the use of other personal protective equipment. RESULTS: The study showed reduction in attenuation of earmuffs due to the use of a full face mask up to 20 dB. Using a full face mask causes that attenuation of earmuffs in the low frequency range is close to zero. Reduction in attenuation due to the use of half masks for complete with particle filters (half masks) is 3-15 dB. Simultaneous use of earmuffs and filtering half masks makes small changes in attenuation not exceeding 3 dB. CONCLUSIONS: The study showed that full face masks give the greatest reduction in attenuation of earmuffs. On the other hand, the least reduction is observed in the case of filtering half masks. There is a significant difference between the reduction in attenuation of earmuffs worn with half masks for complete with particle filters because they may be equipped with different kind of the head strap. Med Pr 2017;68(3):349-361.

Directivity of hearing of auditory danger signal emitted by overhead crane.

BACKGROUND: The objective of the research has been to provide an answer to the question of what the possibilities of determining the direction of approach of the auditory danger signal emitted by an overhead crane appropriately are. Cases of use and no use of earmuffs (in the passive mode and level-dependent ones) were all taken into consideration. MATERIAL AND METHODS: The auditory danger signal and ambient noise were recorded in an industrial hall. Signals were reproduced at an experimental set-up, using a large number of speakers. Eight speakers for reproduction of the auditory danger signal were placed above a subject's head. The study participants would indicate the direction from which, according to them, the auditory danger signal was being emitted. RESULTS: The average percentage rate of the correct localization amounted to 75.8% when the overhead crane's signal wasn't masked. The presence of ambient noise caused a reduction of the number of correctly identified localization to 66.6%. The use of earmuffs in the passive mode resulted in the worst results (44.5%). There is some improvement when level-dependent earmuffs are used (57.3%). CONCLUSIONS: In situations where it is important to identify the direction from which the auditory danger signal generated by the crane's signaling device is approaching, it is beneficial to use level-dependent earmuffs rather than earmuffs in the passive mode. Correct identification of whether the auditory danger signal generated by the crane's signaling device is approaching from the left or right side is almost perfect, however correct identification of whether the signal is approaching from the front or back of a person is not always possible. Med Pr 2016;67(5):589-597.

[ASSESSMENT OF THE AUDIBILITY AREA OF AUDITORY DANGER SIGNALS PRODUCED BY INDUSTRIAL TRUCK]. / OCENA OBSZARU SLYSZALNOSCI DZWIEKOWEGO SYGNALU BEZPIECZENSTWA EMITOWANEGO PRZEZ WÓZEK JEZDNIOWY.

BACKGROUND: The aim of the study was to answer the question what is the audibility area of auditory danger signal emitted by an industrial truck in the noisy environment. MATERIAL AND METHODS: The sound pressure level of the signal produced by the truck horn was measured in 12 directions around the truck, at a distance of 2 to 10 m. It was analyzed, in which places around the truck, auditory danger signal emitted by this truck can be reliably recognized (according to PN-EN ISO 7731). The analysis included 2 types of masking noise. RESULTS: The calculated audibility area in the presence of one type of the noise is about 2-8 m in front of the truck and up to about 3 m on both sides of the truck. Furthermore, itis audible from the rear of the truck, in the range of about 1.5-10 m and 3-7 m, respectively onthe right and left axes of the truck. In the case of high-frequencynoise, despite of its.higher A-weighted equivalent sound'pressure level (12.5 dB), the audibility area is not significantly different. CONCLUSIONS: The presented method of analysis allowed to determine the audibility area of auditory danger signal in the case of considered industrial truck, at the specific workplace. This method can be used in the future to evaluate any auditory danger signal at the workplace, where noise is present. The caselstudy showed that it is possible to encounter a situation where the use of hearing protection devices at the workplace cannot affect the audibility area.

[Assessment of the impulse noise attenuation by earplugs in metalworking processes]. / Ocena ograniczania halasu impulsowego przez wkladki przeciwhalasowe podczas obróbki metalu.

BACKGROUND: The aim of the study was to answer the question of whether earplugs provide sufficient protection in the exposure to impulse noise generated during metalworking processes. MATERIAL AND METHODS: The noise generated by die forging hammer and punching machine was characterized. Using an acoustic test fixture, noise parameters (LCpeak, LAmax) under 24 earplugs, foam, winged and no-roll, were measured. Octave band method was used to calculate values of LAeq under earplugs. RESULTS: It was found that in the case of punching machine the exposure limit value of A-weighted noise exposure level, normalized to an 8-h working day (LEX, 8h = 94.8 dB) of noise present at the workstation, was exceeded, while in the case of die forging hammer both the exposure limit value of this parameter (LEX, 8h = 108.3 dB) and the exposure limit value of peak sound pressure level (LCpeak = 148.9 dB) were exceeded. The assessment of noise parameters (LCpeak, LAmax, LAeq) under earplugs revealed that the noise attenuation can be insufficient, sufficient, or too high. CONCLUSIONS: Earplugs can be suitable hearing protection devices in metalworking processes. Of the 24 earplugs included in this study, 9 provided appropriate noise attenuation in the case of tested die forging hammer and 10 in the case of tested punching machine.

Determining attenuation of impulse noise with an electrical equivalent of a hearing protection device.

Determining the effectiveness of impulse noise attenuation with hearing protection devices (HPDs) is an important part of their selection. Measuring impulse noise parameters under an HPD would involve exposing subjects to impulses with a high peak sound pressure level. This paper presents a computational method of determining impulse noise parameters under the cups of earmuffs. Calculations are done using the transfer function of earmuffs, determined with Shaw's electrical equivalent of an HPD, taking into account the design parameters of earmuffs. The developed method was used for calculations in the presence of impulse noise generated by gunshots. To verify the computational method, the results of these calculations were compared with the results of measurements.

Impulse noise measurement in view of noise hazard assessment and use of hearing protectors.

Experience shows the occurrence of situations when the measurements of impulse noise parameters are made with measurement equipment unsuitable for such conditions. The results of using such equipment were compared with the results of using equipment with a sufficiently large upper limit of the measurement range. The analysis was carried out on the example of noise generated during shots from a Mossberg smooth-bore shotgun and AKM rifle, as well as produced in the forge. The use of the unsuitable equipment allowed to indicate the exceeding of the exposure limit value of the peak value of the signal (LCpeak), but this is not always possible when determining the energy properties of the signal (LEX,8h). While the inadequate properties of the measurement equipment will generally not prevent the conclusion that noise in a particular workplace is hazardous to hearing, the results of measurements cannot be used to select hearing protectors.

Noise Parameters of Headsets Designed for Communication Platforms.

Headsets are increasingly used in the working environment. In addition to being frequently used by call-centre staff, they are also becoming more popular with remote workers and teleconference participants. The aim of this work was to describe and evaluate the acoustic signal parameters reproduced by headsets and examine the factors affecting the values of these parameters. The tests were carried out in laboratory conditions using a manikin (head and torso simulator) designed for acoustic research. A total of 12 headset models were tested during the research. The results show that the A-weighted sound pressure level of the test signal reproduced by four (100% gain) and two (75% gain) headsets exceeded 85 dB. The highest equivalent A-weighted sound pressure level was 92.5 dB, which means that the headset should not be used for more than approx. 1 h and 25 min; otherwise, the criterion value will be exceeded. The analysis of the acoustic signal reproduced by the headsets confirmed that the A-weighted sound pressure level affected the gain level in the test signal reproduction path. This value also depended on the type of connector used, the computer from which the test signal was reproduced and the type of sound card used.

A Tester to Evaluate the Correct Placement of Earplugs.

The use of hearing protection devices is one possible way of reducing the negative impact of noise on hearing. However, it is important to keep in mind that only properly used hearing protection devices provide adequate hearing protection. The aim of this article is to describe a newly developed tester to verify the correct placement of earplugs in the ear canal. This tester was developed using easily accessible and low-cost components. It implements the real-ear attenuation at threshold (REAT) method by which the sound attenuation of hearing protection devices is determined. The headphones with a greater low-frequency attenuation value were selected for use in the tester. The results of the sound attenuation measurement performed with the use of the tester did not differ by more than 5 dB compared to the measurements performed with the use of the Norsonic NOR838 system dedicated to this purpose. The developed tester is considered to be a device that will obtain reliable sound attenuation values. Thus, it can also be used as a device with which the correct placement of earplugs in the ear canal can be assessed.

Effect of musician's earplugs on sound level and spectrum during musical performances.

In this study, change in A-weighted and 1/3 octave sound pressure levels (SPLs) was used to assess the influence of wearing earplugs by musicians on their musical performances. Seven soloists and 3 music assembles performed 4 pieces of music with musician's earplugs donned and doffed. They used silicon custom moulded earplugs with acoustic filters designed to attenuate sound by 9, 15 or 25 dB. Results showed that the use of earplugs affected the sound level and the spectrum of played sounds. This effect was the greatest for brass players. The difference between SPLs in high-frequency 1/3-octave bands and A-weighted SPLs with and without earplugs exceeded 5 and 15 dB, respectively. Similar changes for woodwind, percussion and string instruments were less noticeable than for brass instruments; they were more than 5 dB for 1/3-octave spectra and no more than 2 dB for A-weighted SPL.

[Tests for the correct insertion of earplugs in the ear canal performed with the use of a portable device]. / Badania prawidlowego umieszczania wkladek przeciwhalasowych w przewodzie sluchowym z uzyciem przenosnego urzadzenia.

BACKGROUND: The aim of the study was to assess the correct insertion of earplugs in the ear canal by people with different knowledge regarding this matter. The use of hearing protectors leads to a reduction in the risk of hearing loss, which is part of environmental engineering. MATERIAL AND METHODS: Measurements of sound attenuation by earplugs were carried out with the participation of 21 people with no experience in the use of earplugs. The measurements were repeated until the subjects had read the instructions for the use of earplugs, and then after the subjects had been trained in the correct insertion of earplugs in the ear canal. The tests were carried out using a newly developed portable device for quick measurements of sound attenuation. RESULTS: Familiarizing the subjects with the instructions for use resulted in a sound attenuation value being 6.7 and 3.3 dB higher, at 250 and 4000 Hz, respectively, compared to the measurement when the subjects inserted earplugs in the ear canal without any guidance. An even greater increase in attenuation was observed when the subjects were trained to insert earplugs, at 9.2 dB (250 Hz) and 5.4 dB (4000 Hz), respectively. In most cases, the changes in attenuation as a result of providing guidance were statistically significant. CONCLUSIONS: Persons who have no experience in using earplugs have significant problems with their correct insertion. Reading the instructions for use does not guarantee that earplugs will be inserted correctly. Only the training showing how to insert the earplugs correctly results in people being able to do it correctly in most cases. Med Pr. 2021;72(5):521-8.

The influence of frequency component content on the selection result of hearing protectors.

Hearing protectors are selected for workstation noise using the octave band (OB), HML and SNR methods. The purpose of this study was to determine how the frequency components of the noise can affect the selection of hearing protectors. In total, 55 hearing protectors were selected for four types of real occurring noise, high-frequency noise, low-frequency noise and eight simulated noises. Analysis showed that the noise type affects the accuracy of selection carried out using the HML and SNR methods. For a noise with dominant frequency components, the result for selection carried out using the HML method deviates from the result using the OB method by 7 and 9 dB for earmuffs and earplugs, respectively. The study shows that use of the HML and SNR methods may lead to wrong assessment of the effectiveness of hearing protection with the selected hearing protectors.

Sounds That People with Visual Impairment Want to Experience.

This article presents the expectations of visually impaired people with regard to the content of a set of sound exercises planned for implementation, which will mainly enable these people to become familiar with the sounds associated with specific life situations. Consultations were carried out with 20 people with visual impairment, which allowed for the recognition of the needs of these people regarding the sounds with which they wish to become acquainted. The 35 initially proposed sounds were assessed using a five-grade scale. These sounds included those that would be heard in a number of situations in which a person with a visual impairment could potentially be found, both at home and, for example, while in the street or at an office. During the consultations, people with visual impairment usually rated the sounds proposed for inclusion in the set of sound exercises as highly relevant or relevant. In most cases, the assessment was analogous regardless of whether the person had a visual impairment since birth or developed it relatively recently. There were also more than 100 sounds that were proposed for inclusion in the set. The results of the consultation demonstrate how important the information contained in sound is for people with visual impairment.

Measurement of effective noise exposure of workers wearing ear-muffs.

This paper presents the methodology and the results of binaural measurements of exposure to noise for 91 industry workers wearing ear-muffs. The results revealed that 18.7% of the workers were exposed to noise of equivalent A-weighted sound pressure levels of over 80 dB(A) and 7.7% to levels of over 85 dB(A). The measured levels were compared with those calculated with the octave-band method according to Standard No. EN 458:2004. The differences ranged from -3 dB(A) to 26.5 dB(A); their statistical distribution did not indicate any data which could suggest derating laboratory measurements. The main causes of exposure to noise higher by over 3 dB(A) than that theoretically predicted were the bad technical condition of ear-muffs (32.2% of the cases) and an incorrect way of wearing them (15.2%).

Attenuation of noise by motorcycle safety helmets.

For workers such as police motorcyclists or couriers, traffic and engine noise reaching the ears is an important factor contributing to the overall condition of their work. This noise can be reduced with motorcycle helmets. In this study, insertion loss of motorcycle helmets was measured with the microphone-in-real-ear technique and sound attenuation with the real-ear-at-threshold method. Results for 3 Nolan helmets show essentially no protection against external noise in the frequency range <250 Hz. In the frequency range >500 Hz, attenuation increases linearly at a rate of 8-9 dB per octave, to ~30 dB at 8 kHz. Lack of attenuation in the low-frequency range may cause annoying effects. In addition, high attenuation in the high-frequency range may decrease intelligibility of speech signals for a rider in a helmet. Attenuation measured in this study does not take into account noise generated by turbulent wind around the helmet. Thus, the measured values of attenuation represent a motorcycle rider's best conditions of hearing.

Localization of Vehicle Back-Up Alarms by Users of Level-Dependent Hearing Protectors under Industrial Noise Conditions Generated at a Forge.

The use of hearing protectors in various noisy workplaces is often necessary. For safety reasons, auditory information may be required to correctly localize the direction of an auditory danger signal. The purpose of this study was to verify if the selection of a specific level-dependent hearing protector may be important for the ability to localize a vehicle back-up alarm signal. The laboratory conditions reflected industrial conditions, under which an impulse noise was emitted against a background of continuous noise. A passive mode and a level-dependent mode (maximum and incomplete amplification) were considered. Four different models of level-dependent earmuffs and one model of level-dependent earplugs were included in the tests. The tests enabled differentiation between the individual hearing protectors. The use of earplugs in level-dependent mode did not significantly affect the ability to correctly localize the back-up alarm signal. For the earmuffs, the global assessment of the impact of a mode change revealed that, depending on the model of the earmuffs, the impact may be insignificant, but may also result in considerable impairment of the ability to localize the back-up alarm signal.

Noise reduction at the shooting range by means of level-dependent hearing protectors.

BACKGROUND: The aim of the tests was to establish the possibilities of reducing impulse noise by using level-dependent hearing protectors at a shooting range. The tests included 9 models of level-dependent earmuffs and 2 models of level-dependent earplugs. They were conducted in the presence of impulse noise generated by 7 types of firearms (pistols, a submachine gun, rifles, a shotgun). MATERIAL AND METHODS: The tests were conducted at an outdoor shooting range, using an acoustic test fixture that meets the requirements of the ANSI/ASA S12.42-2010 standard. Noise parameters were established for the noise reaching the microphones installed in the ear simulators of the acoustic test fixture: uncovered and protected by the tested hearing protectors. RESULTS: All 11 tested level-dependent hearing protectors allow to satisfactorily (below the exposure limit values) reduce the C-weighted peak sound pressure level and A-weighted maximum sound pressure level parameters of noise produced during shots from the 7 types of firearms included in the study. Moreover, in the most unfavorable case, the permissible number of impulses due to the value of the A-weighted noise exposure level normalized to an 8-h working day parameter exceeds 5000 per day. CONCLUSIONS: Level-dependent hearing protectors constitute the appropriate means to protect the hearing of people at a shooting range, while maintaining the functionality of these protection devices to transmit speech signals. Med Pr. 2019;70(3):265-73.

Selection of Level-Dependent Hearing Protectors for Use in An Indoor Shooting Range.

The high sound pressure level generated by impulse noise produced in an indoor shooting range makes it necessary to protect the hearing of the people it affects. Due to the need for verbal communication during training at a shooting range, level-dependent hearing protectors are useful. The objective of this study was to answer the question of whether it is possible to properly protect the hearing of a shooting instructor using level-dependent hearing protectors. The noise parameters were measured in the places where the instructor was present at the shooting range. The division of a specific group of trained shooters into subgroups consisting of three or six simultaneously shooting individuals did not significantly affect the exposure of the shooting instructor to the noise. An assessment of noise reduction was carried out for eight models of earmuffs and two variants of earplugs, using computational methods for the selection of hearing protectors. Among the noise parameters, both the A-weighted equivalent sound pressure level and the C-weighted peak sound pressure level were taken into account. Depending on the assessment criterion adopted, a sufficient reduction in impulse noise was provided by either four or six out of the 10 hearing protectors included in the study.

Selection of Earmuffs and Other Personal Protective Equipment Used in Combination.

In a work environment, in addition to noise, people may be exposed to other harmful factors. Therefore, they wear both hearing protectors and other personal protective equipment (OPPE). Incorrect use of such a combination may increase the risk of hearing loss. The aim of this study was to determine whether the simultaneous use of earmuffs and other personal protective equipment could affect the effectiveness of hearing protection. The study was carried out under laboratory conditions using an acoustic test fixture. This fixture replicated the anatomical shapes of the head and the pinnae, and was also equipped with ear simulators. The study was carried out for five models of earmuffs and eight models of other personal protection equipment. We found that a change in the sound pressure level (SPL) under the earmuffs when using a full face respirator could reach up to 40 dB. On the other hand, the use of a half respirator had practically no adverse impact on the efficiency of hearing protection. In the selection process, it is recommended to consider safety spectacles equipped with thin temples, and half respirators equipped with band adjustment elements positioned on the facial part, rather than the back, of the user's head.