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Wyszukujesz frazę "high frequency noise" wg kryterium: Temat


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Tytuł:
Hearing status of people occupationally exposed to ultrasonic noise
Autorzy:
Dudarewicz, Adam
Zamojska-Daniszewska, Małgorzata
Zaborowski, Kamil
Pawlaczyk-Łuszczyńska, Małgorzata
Powiązania:
https://bibliotekanauki.pl/articles/2084911.pdf
Data publikacji:
2022-06-08
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
noise
pure-tone audiometry
otoacoustic emissions
noise-induced hearing loss
ultrasonic noise
extended high-frequency audiometry
Opis:
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.
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2022, 35, 3; 309-325
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydrodynamic analysis of noise propagation by the high skew marine propeller working in non-uniform inflow
Autorzy:
Hadipour, A.
Abadi, K. A. V.
Khanzadi, H.
Motahari, H.
Powiązania:
https://bibliotekanauki.pl/articles/1839886.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
hałas
wahania ciśnienia
śmigło
noise
high skew marine propeller
pressure fluctuating
blade passing frequency
Opis:
Being able to predict ship and marine propulsion noise is an important issue for naval architectures and the international maritime community. The main objective of this paper is the numerical investigation on the noise propagation by the high skew marine propeller working in a non-uniform inflow via RANS solver in the broadband frequency range. The pressure fluctuations were monitored at three points on the propeller blade, then by using the FFT operator we computed the blade passing frequency (BPF) for different propeller loading conditions. Based on these pressure pulses and adopting the Fowcs Williams-Hawking model we calculated noise radiated at the monitoring points. The results showed the BPF and noise level increased by increasing the load on the blades and we also observed that the noise generated at the leading edge was greater than at other points. Furthermore, the study of pressure fluctuations showed the propeller tip has more pressure variations in one revolution than other regions of the propeller surface.
Źródło:
International Journal of Applied Mechanics and Engineering; 2021, 26, 1; 104-121
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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