Ear drum

Persons close to blast seriously injured by lung and hearing damage, fragmentation effects, and from being thrown bodily Ear-drum rupture of almost all persons within the room... 

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,. 

The ear is divided into three sections, these being the outer, middle, and inner ear. The outer ear consists of the pinna and ear canal. The sound wave enters the pinna and travels through the ear canal to the ear drum (tympanic membrane). The outer ear... 

Knock down Ear drum damage Lung damage Threshold for fatalities 50% fatalities 99% fatalities... 

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.

The electric current from the playback head is amplified and sent to an audio speaker, which vibrates in synchronism with the varying current. The back-and-forth motion of the speaker creates pressure waves in the air. This causes the listener s ear drums to vibrate, producing the sensation of sound. 

Cup your hands and clap them simultaneously over your opponent s ears (fig. 1.5). This is a dangerous blow and may burst his ear drums, cause nerve shock, or result in possible internal bleeding. A sharp enough blow can cause a brain concussion and death. 

Figure 8.2 is a cross-sechon of the human ear. Sound is collected and funneled into the ear canal by the outer ear. At the end of the ear canal, the sound impinges upon a membrane called the ear drum. The bones of the middle ear convey the ear drum s vibration to the inner ear. The inner ear consists of a fluid filled Basilar membrane that has tiny hair cells on the inside. The hair cells sense the vibrahon conveyed to the Basilar membrane and convert this into electrical signals that are then conveyed to the brain. 

Note (1) Number of animals in experiment (2) number of being injured (3) myocardial blooding (4) myocardial necrosis (5) mild (6) medium (7) severe (8) mild (9) medium (10) severe (11) empsyxis (12) ruptured ear drum (13) blooding of other organs (14) bladder (15) stomach (16) epinephros (17) spleen (18) brain (19) severe (20) medium (21) mild (22) no... 

Have you ever had an injury to your ears, including a broken ear drum Yes/No... 

Fig. 10.58 Heterodyne measurements of frequency-dependent vibrations of the ear drum and their local variations [1554]...

Sound pressure pulses enter the outer ear and cause the ear drum to vibrate. 

Not only does the electric arc generate an excessive amormt of heat, this heat causes an intense pressure wave that usually throws the employees working nearby away from the arc. This wave is so strong it can break ear drums and cause concussions and broken bones. 

Pain in Tissues As one goes up in altitude, the middle ear vents through the Eustachian tube into the throat to equalize the pressure on both sides of the ear drum. Altitude reduces pressure outside the ear drum until ears pop through a sudden pressure release from the middle ear. This adjustment occurs quite naturally without effort. Swallowing can help to release middle ear pressure. 

When one moves rapidly from altitude to sea level, the surrounding pressure is higher outside the ear drum. It is more difficult to equalize the pressure because the opening of the Eustachian tube in the throat may seal shut. The increase in atmospheric pressure can create pain. 

The middle ear begins on the inner side of the ear drum. The middle ear is an air-filled chamber that vents to the throat through the Eustachian tube. It contains three small bones (ossicles) and two suspensory muscles for them. The three bones are the maleus (hammer), the incus (anvil), and the stapes (stirrup). Sound energy travels across the three bones from the tympanic membrane of the outer ear to the oval window of the inner ear. The action of these three bones produces an amplification of about 2.5 dB. The suspensory muscles are the tensor tympani and the stapedius. When there is a loud sound, these muscles contract and provide some attenuation of energy transmitted across the three bones. 

The formulation of ear drops, especially the choice of the vehicle, depends on the site of action the external auditory canal or the middle ear. When ear drops get to the middle ear, they may come into contact with the inner ear and so cause ototoxicity. Because of the ototoxicity of active substances, non-aqueous vehicles and many other excipients, special precautions are needed in formulations that should, or may accidentally, come into contact with the middle ear. Preparations intended for the middle ear are aqueous, sterile and preferably iso-osmotic. When non-aqueous vehicles are used in ear drops for the external auditory canal, it depends on the state of the patient s ear drum whether they will reach the middle ear. 

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

These vibrations are transmitted through the middle ear by three tiny bones known as the ossicles, being the hammer (malleus), anvil (incus) and stirrup (stapes). The hammer bone is fixed to the ear-drum and the stirrup to another membrane (the oval window) which separates the middle and inner parts of the ear. The section of the inner ear which receives sound waves is shaped like a snail s shell (the cochlea) and contains strands of tissue under varying tensions. These strands vibrate in response to sound waves of particular frequency which have entered the inner ear from the bones of the middle ear and produce nerve impulses in the auditory nerve which are then transmitted to the cortex of the brain. It is at this point that the signals are received as sound of a certain pitch, intensity and quality. 

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