Hearing protection and communication
Nicholas Green, Steven Gaydos, Hutchison Ewan, Edward Nicol in Handbook of Aviation and Space Medicine, 2019
Earplugs (generic fit or personally moulded) are worn in ear canal underneath helmet, forming double hearing protection system: Passive earplugs: attenuate both cockpit noise and communications signal.In-ear communications devices (IECDs): include small transducers allowing communication signal to be introduced on occluded side of earplug.ANR earplugs: include circuitry and provide similar levels of additional active attenuation as flight helmet ANR.Vented earplugs for high altitude: occlusion of external ear canal may cause pressure differentials across tympanic membrane which may be slow to equalize, particularly during explosive decompression.
Ballistic weaponry, blast and personal protective equipment development
Ian Greaves in Military Medicine in Iraq and Afghanistan, 2018
In 2001, hearing protection for UK Armed Forces personnel was provided in the form of foam earplugs and passive ear defenders. The Combat Arms Ear Plug was introduced for UK Armed Forces personnel in 2006 and provided two levels of protection determined by which colour end of the plug was inserted into the ear.60 The acceptance of these methods of hearing protection by Armed Forces personnel on deployment was generally poor, with most preferring to maintain situational awareness by not using them and running the risk of hearing loss.60 Following a UOR, the Personal Interfaced Hearing Protection (PIHP) system was introduced in March 2009 for Armed Forces personnel deploying to Afghanistan. The system incorporated translucent silicone custom-moulded earplugs that attached to the in-ear headset (Figure 10.23). The headset attached to the talk through switch box, which in turn connected to the Personal Role Radio (PRR). However a study undertaken by clinicians in 2011 demonstrated that only 4% of those UK Armed Forces personnel issued with PIHP used it.59 This was found to reflect a lack of awareness of how to use the system and a dislike of the reduction in situational awareness it caused when it was worn.
Noise-Induced Hearing Loss and Related Conditions
John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed in Paediatrics, The Ear, Skull Base, 2018
There is evidence that the use of hearing protection reduces the risk of NIHL from noise in both recreational and occupational contexts.83,84 As regards hearing protection, the choice is between earplugs, earmuffs and active noise reduction. The choice will often depend on the performance of the protector and the environment in which it will be used. Earplugs may be personally moulded or ‘off the shelf’, and are made from silicone rubber, acrylics or closed cell foam. They are relatively cheap and particularly useful when other protective devices (e.g. helmets or goggles) must also be worn. The best earplug can perform as well as the best earmuff in terms of sound attenuation but they are harder to fit correctly.85 It is well established that the real-world performance of ear protectors is significantly poorer than the laboratory scores, largely as a result of inadequate or incorrect fitting. Therefore, earmuffs are generally a more reliable form of ear protector. In a real-world setting, earplugs can be assumed to give approximately 10–15 dB of sound attenuation and earmuffs at least 15 dB.86
How hearing conservation training format impacts personal attenuation ratings in U.S. Marine Corps Training Recruits
Published in International Journal of Audiology, 2021
Jeremy Federman, Stephanie J. Karch, Christon Duhon
Ample evidence indicates that when properly fitted, earplugs are effective at attenuating noise (Federman and Duhon 2016; Pääkkönen et al. 2000). The amount of earplug attenuation (in dB) achieved by users in the real world has been reported to be associated with insertion depth, earplug shape and material, the anatomical characteristic of the ear/head, and fitting techniques (Berger 2013; Joseph et al. 2007; Murphy et al. 2011; Samelli et al. 2018; Tufts, Chen and Marshall 2013). For example, Tufts et al. (2013) found that, the deeper a custom earplug is inserted, the greater the amount of achieved attenuation by the user. Similarly, Berger (2013) reported that the amount of attenuation a foam earplug affords its user is influenced by both the depth of its insertion and its physical shape (e.g. tapered, cylindrical). Samelli et al. (2018) reported higher PAR values when foam earplugs were used compared to that of pre-molded earplugs. In addition, Berger (1996a) reported that less than 10% of employees likely have ear canals that vary in size, and to achieve proper fit, these persons would likely require use of two different sized earplugs.
Use of a modified bubble continuous positive airway pressure (bCPAP) device for children in respiratory distress in low- and middle-income countries: a safety study
Published in Paediatrics and International Child Health, 2019
Ashley R. Bjorklund, Beatrice Odongkara Mpora, Marie E. Steiner, Gwenyth Fischer, Cynthia S. Davey, Tina M. Slusher
SEAL-bCPAP was constructed using inexpensive materials available in most LMIC. Materials included a simple nasal cannula, oxygen tubing, disposable water bottles, ‘superglue’, tape and commercial compressible ear-plugs (3 M™ tekk protection, Disposable Earplugs) (Figure 1(A)). The oxygen source was cylinder or concentrator. The nasal interface was modified by stretching a small cut ring of compressible ear-plug material over the end of each nasal prong and attaching it with superglue (Figure 1(B)). This material was pinched and held for a few seconds on the nasal prong. The prongs, with the compressed material, were slipped into the nares and allowed to expand to create a more occlusive intranasal seal. SEAL-bCPAP was designed to not rely on electricity or require intensive monitoring and cost about US$5. If needed, the apparatus could be cleaned and re-used, except the earplug material which was removed and replaced.
Method for protected noise exposure level assessment under an in-ear hearing protection device: a pilot study
Published in International Journal of Audiology, 2021
Vincent Nadon, Fabien Bonnet, Rachel E. Bouserhal, Antoine Bernier, Jérémie Voix
Another promising way of assessing adequate protection with HPDs is in-ear noise dosimetry (IEND) [1,19–21]. IENDs give a more accurate estimate of the residual noise level reaching the eardrum than regular noise dosimeters, which monitor noise levels outside the earcanal [22], because IENDs bypass the need for assumptions and correction factors for microphone placement. In addition, such an approach has also recently proven to raise awareness among workers as the noise exposure feedback helped them reduce their noise dose through more appropriate HPD use [23]. However, the SPL measured inside the earcanal may be affected by various wearer-induced disturbances (WID) [24] such as talking, coughing or chewing, as well as microphonics, which are amplified by the occlusion effect when wearing an earplug [25]. As a result, the earplug can increase the measured in-ear noise dose instead of reducing it. However, middle-ear mechanisms [9,10], such as the stapedial reflex and nervous system mechanisms [11], are known to be triggered by self-generated noises, such as chewing or speaking. These mechanisms attenuate the intensity with which these self-generated noises ultimately reach the inner ear [10]. Hence, IENDs would benefit from a method to isolate the contribution of such WIDs from the calculated in-ear noise dose to help reflect the real effects of noise exposure levels and duration on the auditory system and better understand why a given individual may seem overexposed based on the SPL measured inside the earcanal [26]. Yet, to this day, commercial IENDs do not feature this option which would be beneficial for future research on occupational hearing loss to properly model the relationship between noise exposure and hearing damage.
Related Knowledge Centers
- Ear Canal
- Hearing Loss
- Tinnitus
- Eardrum
- Hearing Protection Fit-Testing
- Occupational Noise
- Wax
- Silicone
- Headphones
- Snoring