Ear damage

The ear is a very sensitive and complex organ that responds to very small variations in pressure. It was argued in Hirsch (1968) that ear drum rupture is decisive as to ear damage from blast waves. Figure C-3 shows the percentage of eardrum ruptures as a function of side-on overpressure F,. 

Overpressure duration probably has some influence on ear damage, but no literature on this subject was found. Because the ear can respond to high frequencies, blast wave loading normally lies in the pressure region rather than in the impulse region. 

Figure 41. Human Ear Damage for Blast Waves Arriving at Normal Angle of Incidence. (Ref. 46)...

Direct application of phenol to the inner ear of rats has resulted in external otitis, inner ear damage, and decreased brain-stem auditory response (Schmidt et al. 1990), and inflammation of the tympanic membrane (Schmidt and Hellstrom 1993). These studies were conducted because phenol has been used as a topical anesthetic in infected ears. 

Symptoms Young larvae feed on corn leaves and tassels and beneath husks, damaging the ears. Older larvae burrow in corn stalks and ears damaged stalks may break. Larvae also tunnel in the stems or pods of beans, onions, peppers, potatoes, tomatoes, and other crops. 

TM rupture and middle-ear damage. Abdominal hemorrhage and perforation—globe (eye) rupture-concussion (TBI without physical signs of head injury). 

Figures 28.9, 28.10, and 28.11 show this relationship for humans. The figures differ in the body orientation relative to the incoming shock. Figure 28.12 shows the 1% and 50% probabilities of adverse ear responses in relation to pressure and pulse duration for three different levels of ear injury. Level 1 consists of minor damage and/or healable small tears or rupture of the tympanic membrane (ear drum) level 2 for tearing of the membrane that will result in permanent hearing loss and level 3, which includes severe rupture of the membrane along with inner ear damage.

When dealing with ear damage potential, pressures are often expressed as db noise level. This is a log transform of pressure in normal units. The transform (relative to 2 X 10 p,bar) is... 

A noise level of 75 decibels generates high levels of stress in most people. Tinnitus, or ringing in the ear, may occur at 80 decibels. The 100 decibels regularly encountered in night clubs can cause ear damage after only fif-... 

In 30 years of practice, I have not recognized a single ear damaged in hearing from any antibiotic ear drop, however long term. This total experience has not changed since then. 

In man, differences in the ototoxic risks of the currently used aminoglycosides are difficult to evaluate (20). There have been no prospective comparisons of more than two drugs using the same criteria in similar patient populations. However, several controlled comparisons of two aminoglycosides are available and provide some information. A survey of 24 such trials showed the following mean frequencies of ototoxicity gentamicin 7.7%, tobramycin 9.7%, amikacin 13.8%, netilmicin 2.3% (28). There was also a lower incidence of netilmicin-induced inner ear damage compared with tobramycin in two studies (29,30). 

Viral and bacterial diseases also represent great danger for the maturing embryo. The damage caused by the roseola virus (eye and ear damage and cardiac defects) is well known. 

Kellerhals B (1978) Risk of inner ear damage from ototoxic eardrops. HNO 26 46-52... 

Hearing Obstructed ear canal, perforated ear drum, middle ear damage, catarrh, ear plugs or muffs altering the sound reaching the ear... 

Noise can lead to ear damage on a temporary (acute) or permanent (chronic) basis. 

The auditory damage caused by noise, NIHL, depends on exposure type sound level, duration, type of noise, and frequency, as well as personal factors like susceptibility to noise, age, smoking, prior history of hearing/ear damage (Rezaee et al., 2011). The approach to evaluate and prevent this should be multidisciplinary task covering all aspects related to noise and noise effects and their combined interactions. Actually, these interactions, impulsiveness of noise, genetic susceptibility, ototoxic chemicals and leisure noise cannot be modelled (Rabinowitz et al., 2013). 

Irmer-ear damage resulting from blast exposure is rare but can occur, even without ossicular disruption. Injuries include fistulae in the oval window, dislocation of the stapes and ruptures of the saccule, utricle and basilar membrane. In such cases, profound hearing loss is foimd in association with otorrhoea. 

Incident wave at right angles to external auditory meati, ear damage unlikely... 

Incident wave along axis of external auditory meatus significant risk of ear damage... 

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