The mechanisms of passive ear defenders

Paurobally, M.R.; Pan, Jin

doi:10.1016/s0003-682x(99)00045-6

Cited by 12 publications

(18 citation statements)

References 4 publications

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“…The F4 earplug used 'memory foam'; the W0 and P7 were of similar shape and used 'closed cell' PVC foam, the W9 used 'open cell foam' and the CL 'closed cell' polythene foam. In theoretical models it has been shown that both the design and materials used in the construction of ear defenders is likely to impact upon their performance (Paurobally and Pan 2000). However, this study was not designed to compare the materials or design of earplugs, but rather the effectiveness of the two combined.…”

Section: Discussionmentioning

confidence: 99%

“…The amount of cotton wool selected for its construction was arbitrary as was the grade of cotton wool used. Changing either of these two attributes could affect the performance of a cotton wool earplug (Paurobally and Pan 2000). One potential clinical disadvantage of the CW earplug is that unlike most of the commercial designs it does not feature a lanyard, and so removal of the earplug may be more difficult.…”

Section: Discussionmentioning

confidence: 99%

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Preliminary investigation into the effects of earplugs on sound transmission in the equine ear

MacFarlane¹,

Mosing²,

Burford³

2010

PHK

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SummaryEarplugs are occasionally used to reduce horses responsiveness to noise but there performance has not been evaluated. A modified 'microphone in real ear' technique was used to quantitatively assess the effects of several earplugs on sound transmission in the external ear of equine cadavers. Significant variations in the performance of the earplugs tested were identified. These results may affect the selection of earplugs for clinical use and should inform the design of future investigations into the clinical utility of earplugs in horses

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Preliminary investigation into the effects of earplugs on sound transmission in the equine ear

MacFarlane¹,

Mosing²,

Burford³

2010

PHK

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“…Evidently, the air cavity enclosed by the ear cup would take the boundary profile of a highly irregular shape. However, Boyer et al [28] and Paurobally and Pan [29] mentioned that the acoustic stiffness of the air cavity could be approximated by considering it as a hemicylindrical volume. In this case, the acoustic stiffness of the air cavity air is given by [28] …”

Section: Acoustical Performance Of the Composite Earmuffs In Pinkmentioning

confidence: 99%

Low-Frequency Noise Reduction by Earmuffs with Flax Fibre-Reinforced Polypropylene Ear Cups

Ang

Tran

Phillips

et al. 2018

Advances in Acoustics and Vibration

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Soldiers and supporting engineers are frequently exposed to high low-frequency (<500 Hz) cabin noise in military vehicles. Despite the use of commercial hearing protection devices, the risk of auditory damage is still imminent because the devices may not be optimally customised for such applications. This study considers flax fibre-reinforced polypropylene (Flax-PP) as an alternative to the material selection for the ear cups of commercial earmuffs, which are typically made of acrylonitrile butadiene styrene (ABS). Different weaving configurations (woven and nonwoven) and various noise environments (pink noise, cabin booming noise, and firing noise) were considered to investigate the feasibility of the proposed composite earmuffs for low-frequency noise reduction. The remaining assembly components of the earmuff were kept consistent with those of a commercial earmuff, which served as a benchmark for results comparison. In contrast to the commercial earmuff, the composite earmuffs were shown to be better in mitigating low-frequency noise by up to 16.6 dB, while compromising midfrequency acoustical performance. Consequently, the proposed composite earmuffs may be an alternative for low-frequency noise reduction in vehicle cabins, at airports, and at construction sites involving heavy machineries.

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“…In the case of a perfect sealing between the cushion and the baffle and the foam insert being removed from the cup, the sound attenuation of the earmuff given by the analytical models (Zwislocki, 1955;Shaw and Thiessen, 1958;Paurobally and Pan, 2000;Sides, 2004;Du and Homma, 2009) can be expressed as…”

Section: Lpms Formulationsmentioning

confidence: 99%

“…The analytical models are usually lumped parameters models (LPMs), such as the one developed by Zwislocki (1955), Shaw and Thiessen (1958), Paurobally and Pan (2000), Sides (2004), Du andHomma (2009), andKalb (2010). They are used to model the sound attenuation of circumaural HPDs at low frequency, typically <1 kHz.…”

Section: Introductionmentioning

confidence: 99%

Low frequency finite element models of the acoustical behavior of earmuffs

Boyer

Doutres

Sgard

et al. 2015

The Journal of the Acoustical Society of America

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This paper compares different approaches to model the vibroacoustic behavior of earmuffs at low frequency and investigates their accuracy by comparison with objective insertion loss measurements recently carried out by Boyer et al. [(2014). Appl. Acoust. 83, 76-85]. Two models based on the finite element (FE) method where the cushion is either modeled as a spring foundation (SF) or as an equivalent solid (ES), and the well-known lumped parameters model (LPM) are investigated. Modeling results show that: (i) all modeling strategies are in good agreement with measurements, providing that the characterization of the cushion equivalent mechanical properties are performed with great care and as close as possible to in situ loading, boundary, and environmental conditions and that the frequency dependence of the mechanical properties is taken into account, (ii) the LPM is the most simple modeling strategy, but the air volume enclosed by the earmuff must be correctly estimated, which is not as straightforward as it may seem, (iii) similar results are obtained with the SF and the ES FE-models of the cushion, but the SF should be preferred to predict the earmuff acoustic response at low frequency since it requires less parameters and a less complex characterization procedure.

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The mechanisms of passive ear defenders

Cited by 12 publications

References 4 publications

Preliminary investigation into the effects of earplugs on sound transmission in the equine ear

Preliminary investigation into the effects of earplugs on sound transmission in the equine ear

Low-Frequency Noise Reduction by Earmuffs with Flax Fibre-Reinforced Polypropylene Ear Cups

Low frequency finite element models of the acoustical behavior of earmuffs

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