Effects of Overpressure on the Ear: A Review

Hirsch, Frederic G.

doi:10.21236/ad0653129

Cited by 10 publications

(10 citation statements)

References 2 publications

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“…When exposed to a blast, the human auditory system is vulnerable to both peripheral and central damage from the overpressure (Patterson and Hamernik, 1997; Mayorga, 1997). Rupture of the eardrum or tympanic membrane (TM) is the most frequent injury of the ear and has been investigated in animals and humans with wide variability (Hirsch, 1966; Patterson and Hamernik, 1997; Richmond et al, 1989). The literature indicates that mechanical damage to components of the auditory system is the major cause for hearing loss after blast exposure.…”

Section: Introductionmentioning

confidence: 99%

Mechanical damage of tympanic membrane in relation to impulse pressure waveform – A study in chinchillas

Gan

Nakmali

et al. 2016

Hearing Research

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Mechanical damage to middle ear components in blast exposure directly causes hearing loss, and the rupture of the tympanic membrane (TM) is the most frequent injury of the ear. However, it is unclear how the severity of injury graded by different patterns of TM rupture is related to the overpressure waveforms induced by blast waves. In the present study, the relationship between the TM rupture threshold and the impulse or overpressure waveform has been investigated in chinchillas. Two groups of animals were exposed to blast overpressure simulated in our lab under two conditions: open field and shielded with a stainless steel cup covering the animal head. Auditory brainstem response (ABR) and wideband tympanometry were measured before and after exposure to check the hearing threshold and middle ear function. Results show that waveforms recorded in the shielded case were different from those in the open field and the TM rupture threshold in the shielded case was lower than that in the open field (3.4±0.7 vs. 9.1±1.7 psi or 181±1.6 vs. 190±1.9 dB SPL). The impulse pressure energy spectra analysis of waveforms demonstrates that the shielded waveforms include greater energy at high frequencies than that of the open field waves. Finally, a 3D finite element (FE) model of the chinchilla ear was used to compute the distributions of stress in the TM and the TM displacement with impulse pressure waves. The FE model-derived change of stress in response to pressure loading in the shielded case was substantially faster than that in the open case. This finding provides the biomechanical mechanisms for blast induced TM damage in relation to overpressure waveforms. The TM rupture threshold difference between the open and shielded cases suggests that an acoustic role of helmets may exist, intensifying ear injury during blast exposure.

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Section: Introductionmentioning

confidence: 99%

Mechanical damage of tympanic membrane in relation to impulse pressure waveform – A study in chinchillas

Gan

Nakmali

et al. 2016

Hearing Research

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“…19,20 A limited number of animal and human studies have demonstrated the physical limits of the tympanic membrane resulting in perforation. [21][22][23][24][25] In 1906, Zalweski conducted experiments on fresh cadeveric eardrums. He reported that minimal and maximal pressures of TM rupture resulted at 5.4 and 43 psi, respectively, with mean pressure of 23 psi.…”

Section: Tympanic Membranementioning

confidence: 99%

Otologic Considerations of Blast Injury

Darley

Kellman²

2010

Disaster med. public health prep.

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ABSTRACTThe ear by design is exquisitely sensitive to barotrauma. As a result, it is typically the first organ affected in primary blast injury. The most common symptoms encountered include hearing loss, ringing, and drainage. In severe cases, the highest priority is appropriately directed toward diagnosis and treatment of life-threatening injuries; however, injury to the ear is missed frequently. With simple screening procedures, limited management, and appropriate otolaryngologic referral, acute and long-term morbidity can be averted for both critical and noncritical patients. The article provides an overview of blast mechanics and pathophysiology. It details various blast-related injuries to the external, middle, and inner ear. Standard of care assessment and management strategies are presented for acute and late otologic sequelae of the blast-injured patient.(Disaster Med Public Health Preparedness. 2010;4:145-152)

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“…There has never been a work-related traffic fatality to SLA persons on the base. Although an overpressure of 5 psi may break a man's eardrums (Hirsch, 1968) These ERDA regulations reduce to a practical minimum the possibility of a significant release of radioactivity in the course of handling or transportation, and in fact there has never been such a release by SLA on base since SLA was established. Still, the potential impact of such a release must be discussed.…”

Section: Accident Analysismentioning

confidence: 99%

Environmental Impact Assessment Sandia Laboratories, New Mexico.

NM¹

1977

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This Omnibus Environmental Assessment describes the ongoing operations of the Sandia Laboratories, Albuquerque, (SLA) and evaluates the actual and possible impacts on the environment that continuation of these operations entails. Since the Laboratories predates the National Environmental Policy Act of 1969 (NEPA) by two decades, there previously has been no overall formal retrospective environmental assessment of the whole of its facilities and operational although each facility that postdates NEPA has been assessed for its potential environmental impact. The SLA plant and facilities are owned by the U.S. Government, and are operated by Bell System through a contract between the Western Electric Company and the U.S. Atomic Energy Commission (now the U.S. Energy Reserach and Development Administration (ERAD) as a prime contractor (Sandia Corporation) of the ERDA. All laboratory ongoing activities are discussed, except that this asessment does not evaluate the consequence of possible terrorist activity against the laboratory facilities, nor does it concern itself with transportation hazards outside Kirtland AFB East. Precautionary measures are in effect to assure that all nuclear materials are secure. The internal accounting system shows the locations and quantities of all nuclear material at all times.

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Effects of Overpressure on the Ear: A Review

Cited by 10 publications

References 2 publications

Mechanical damage of tympanic membrane in relation to impulse pressure waveform – A study in chinchillas

Mechanical damage of tympanic membrane in relation to impulse pressure waveform – A study in chinchillas

Otologic Considerations of Blast Injury

Environmental Impact Assessment Sandia Laboratories, New Mexico.

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