Attenuation of earmuffs used simultaneously with safety spectacles in exposure to impulse noise

Impulse noise is particularly hazardous to the hearing of exposed individuals. In many real-life scenarios, the only protective measure used to reduce the level of impulse noise is hearing protectors. These scenarios include firing ranges. Aside from hearing protectors, shooters use personal safety spectacles. The purpose of this paper was to determine the effect of the simultaneous use of earmuffs and safety spectacles on the sound attenuation of earmuffs during exposure to impact noise. The research was completed with the MIRE method and included the determination of sound attenuation changes in five different models of earmuffs, used simultaneously with three different models of safety spectacles and prescription glasses. The impulse noise source used was a starting pistol, which generated C-weighted peak sound pressure level at a mean of 136.7 dB. The tests demonstrated that the simultaneous use of safety spectacles and earmuffs reduces the impulse noise attenuation of the earmuffs by up to 9 dB. Such sound attenuation changes occurred during simultaneous use of earmuffs with safety spectacles, which feature temples with a rectangular cross-section. The tests also demonstrated that the effect of prescription glasses on sound attenuation was unusually high; prescription glasses reduced the impulse sound attenuation of earmuffs by as much as 18 dB. Keywords: acoustics, noise protection, impulse noise, hearing protectors, earmuffs, noise attenuation

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Determination of the noise attenuation of hearing protectors by numerical modeling of the outer ear

The Journal of the Acoustical Society of America ◽

10.1121/1.421743 ◽

1998 ◽

Vol 103 (5) ◽

pp. 3004-3004

Author(s):

Samir N. V. Gerges ◽

Elizabete Y. Bavastri

Keyword(s):

Numerical Modeling ◽

Noise Attenuation ◽

Hearing Protectors

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Measurement of Earmuffs Attenuation at High Audible Frequencies

Archives of Acoustics ◽

10.1515/aoa-2017-0027 ◽

2017 ◽

Vol 42 (2) ◽

pp. 249-254

Author(s):

Emil Kozłowski ◽

Rafał Młyński

Keyword(s):

Frequency Band ◽

Measurement Method ◽

Sound Attenuation ◽

The Other ◽

Hearing Protection ◽

Noise Attenuation ◽

Frequency Range ◽

Test Fixture ◽

Hearing Protectors ◽

Audible Frequency

Abstract Standardised measurements of sound attenuation of hearing protectors are performed in the frequency range from 125 Hz to 8 kHz. However, noise present at many workplaces contains significant components at higher audible frequency. Therefore, the knowledge about noise attenuation with earmuffs in the audible frequency range above 8 kHz is also necessary for proper hearing protection. The aim of this study was to obtain values of the noise attenuation with 27 commonly-used earmuffs models in the 1/3 octave bands of 10, 12.5 and 16 kHz. The measurements were conducted with a real ear at threshold (REAT) method with participation of subjects. The study showed that attenuation of earmuffs ranged from 24.7 to 42.8 dB, depending on model of earmuffs and frequency band. Furthermore, the measurements were performed with the use of acoustic test fixture which is designed especially for testing hearing protectors. Results obtained with the use of acoustic test fixture indicated that this measurement method can lead to values close to attenuation measured with participation of subjects. On the other hand, values obtained with the use of acoustic test fixture may differ average up to 14 dB from REAT method.

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The Uniform Flexure of an Incomplete Tore

Australian Journal of Chemistry ◽

10.1071/ch9490469 ◽

1949 ◽

Vol 2 (4) ◽

pp. 469

Author(s):

W Freiberger ◽

RCT Smith

Keyword(s):

General Solution ◽

Cross Section ◽

Harmonic Functions ◽

Rectangular Cross Section ◽

Three Dimensional ◽

Elasticity Problems ◽

Three Dimensional Elasticity ◽

Derivatives Of ◽

Special Case

In this paper we discuss the flexure of an incomplete tore in the plane of its circular centre-line. We reduce the problem to the determination of two harmonic functions, subject to boundary conditions on the surface of the tore which involve the first two derivatives of the functions. We point out the relation of this solution to the general solution of three-dimensional elasticity problems. The special case of a narrow rectangular cross-section is solved exactly in Appendix II.

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Determination of kinetic coefficients for treating synthetic oily wastewater in suspended growth batch fed reactor

Water Science & Technology ◽

10.2166/wst.2021.377 ◽

2021 ◽

Author(s):

P. Sanghamitra ◽

Debabrata Mazumder ◽

Somnath Mukherjee

Keyword(s):

Real Life ◽

Oily Wastewater ◽

Efficient Design ◽

Oil And Grease ◽

Property A ◽

Kinetic Coefficients ◽

Suspended Growth ◽

Suspended Biomass ◽

High Level

Abstract Discharge of oily wastewater imparts serious threat to the environment because of high level concentration of COD, BOD as well as oil and grease and it is difficult to treat such wastewater due to its inherent toxic and inhibitory property. A treatability study of oily wastewater (carrying petroleum) has been performed in the present work using a batch suspended growth reactor. The experiment was conducted using acclimatized suspended biomass in laboratory environment and the kinetic coefficients were determined which are immensely important for design of such reactor. The oil removal efficiency was observed to be in the range of 62.84–85.45% corresponding to average MLSS concentration range of 1,797–3,668 mg/L. Haldane kinetic model was found to be the best fitted for the biodegradation of oily wastewater with acclimatised microorganisms in the present investigation. The kinetic co-efficients including Ks, Y, kd, k and ki were calculated from the experimental data and the values were compared with published results cited by various scientists. The derived kinetic coefficients values are to be useful for understanding the dynamics of substrate utilisation with production of biomass and efficient design of biological systems and also for pilot plant investigation with real life wastewater of similar nature.

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Determination of the electric vehicles driving modes in real life conditions by classification methods

2018 IEEE International Conference on Industrial Technology (ICIT) ◽

10.1109/icit.2018.8352506 ◽

2018 ◽

Author(s):

Mohamed Ben-Marzouk ◽

Guy Clerc ◽

Serge Pelissier ◽

Ali Sari ◽

Pascal Venet

Keyword(s):

Electric Vehicles ◽

Real Life ◽

Classification Methods ◽

Life Conditions

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Evaluation of effectiveness and compliance with the mupirocin nasal ointment part of Staphylococcus aureus decolonization in real life using UPLC-MS/MS mupirocin quantification

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/dkaa025 ◽

2020 ◽

Vol 75 (6) ◽

pp. 1623-1630 ◽

Cited By ~ 2

Author(s):

Roxane Nicolas ◽

Anne Carricajo ◽

Jérôme Morel ◽

Josselin Rigaill ◽

Florence Grattard ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Cardiac Surgery ◽

Real Life ◽

Nasal Carriage ◽

Nasal Sample ◽

Real Life Setting ◽

Increased Risk ◽

Nasal Mupirocin ◽

Compliance Issue

Abstract Background Preoperative decolonization is recommended in Staphylococcus aureus nasal carriers scheduled for cardiac surgery. We aimed to evaluate the effectiveness of and compliance with mupirocin use in nasal S. aureus carriers in a real-life setting. Methods Prospective study including consecutive patients scheduled for cardiac surgery screened for S. aureus nasal carriage at preoperative consultation. Carriers were prescribed mupirocin nasal ointment, chlorhexidine shower and mouthwash. Effectiveness of decolonization was evaluated with a postoperative nasal sample. Compliance was evaluated objectively by determination of nasal mupirocin concentration using UPLC-MS/MS and self-reported by questionnaire. Results Over 10 months, 361 patients were included, 286 had preoperative screening, 75 (26.2%) were S. aureus nasal carriers and 19 of them (25.3%) failed to be effectively decolonized. No resistance to mupirocin was documented. Preoperative and postoperative strains were identical in all cases. Declared good compliance was associated with decolonization success (OR = 24; 95% CI 4–143, P < 0.0001). Mupirocin detection was significantly associated with the level of compliance. Mupirocin was detected in 52.2% (24/46) of patients effectively decolonized and in 12.5% (2/16) of patients with decolonization failure (P < 0.01). In 2/19 patients, failure of decolonization was not associated with a compliance issue. Postoperative carriage was associated with an increased risk of S. aureus infection (OR = 9.8; 95% CI 1.8–53, P < 0.01). Conclusions In real life, decolonization is not always effective, hence there is a persisting risk of S. aureus endogenous infection. Mupirocin concentration measurement may help to understand compliance issues and failures in decolonization.

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