Wyniki wyszukiwania - Biblioteka Nauki

1

Attenuation of Noise by Motorcycle Safety Helmets

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Młyński R. , Kozłowski E. , Żera J.

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tom Vol. 15, No. 3

287--293

EN

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.

2

Ocena hałasu generowanego przez skanery rezonansu magnetycznego i jego wpływu na narząd słuchu - badania pilotażowe

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Morzyński L. , Kozłowski E. , Młyński R. , Karpowicz J.

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tom Vol. 17, nr 4

292-296

PL

W pracy przedstawiono wyniki badań hałasu wytwarzanego przez skanery rezonansu magnetycznego o indukcji magnetycznej 1,5 T. Wykazano dużą rozpiętość wartości ciśnienia akustycznego hałasu w zależności od rodzaju badania. Równoważny poziom dźwięku A (LAeq,Tp) zawierał się w przedziale 69,8-96,3 dB, maksymalny poziom dźwięku A (LAmax) w przedziale 81,4-106,8 dB, a szczytowy poziom dźwięku C w przedziale 98-116,7 dB. Przeprowadzona ocena zagrożenia hałasem pracowników dowodzi, że długotrwałe przebywanie w pobliżu pracującego skanera może powodować przekroczenie wartości dopuszczalnego narażenia i prowadzić do uszkodzenia słuchu.

EN

In this paper, the results of examination of acoustic noise, generated by 1,5 T magnetic resonance scanners, are reported. The measurement results showed the wide range of sound pressure level values, depending on the type of examination. The A-weighted equivalent sound level (LAeq,Tp) was in the range of 69,8-96,3 dB, the maximum A-weighted sound level (LAmax) maintained within the range of 81,4-106,8 dB, and the peak C-weighted sound level was in the range of 98-116,7 dB. The assessment of the occupational hazard, resulting from the exposure to the noise revealed that the prolonged contact with an active scanner may result in overcome of the maximum allowable level of exposure to acoustic noise and thus, it may cause the hearing damage.

3

Evaluation of Exposure to Impulse Noise at Personnel Occupied Areas During Military Field Exercises

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Młyński R. , Kozłowski E. , Usowski J. , Jurkiewicz D.

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tom Vol. 43, No. 2

197--205

EN

The tests reported in this paper were carried out to evaluate the exposure of soldiers to noise at operator and control positions during military field exercises. The tests were conducted during firing from a T-72 tank, a BWP-1 Infantry Fighting Vehicle, antitank guided missiles, a ZU-23-2K anti-aircraft gun, and a 2S1 GOZDZIK howitzer. The evaluation of noise exposure showed that the limit values of sound pressure level, referred to by both Polish occupational noise protection standards and the Pfander and Dancer hearing damage risk criteria developed for military applications, were repeatedly exceeded at the tested positions. Despite of the use of tank crew headgear, the exposure limit values of sound pressure level were exceeded for the crew members of the T-72 tank, the BWP-1 infantry fighting vehicle, and the 2S1 GOZDZIK howitzer. The results show that exposure of soldiers to noise during military field exercises is a potentially high hearing risk factor.

4

Effect of Musician’s Earplugs on Sound Level and Spectrum During Musical Performances

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Kozłowski E. , Żera J. , Młyński R.

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2011

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tom Vol. 17, No. 3

249--254

EN

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.