The ear is the organ that detects sound. It not only acts as a receiver for sound, but plays a major role in the sense of balance and body position. The ear is part of the auditory system. The word "ear" may be used correctly to describe the entire organ or just the visible portion. Vertebrates have a pair of ears, placed symmetrically on opposite sides of the head. This arrangement aids in the ability to localize sound sources.
Audition is the scientific name for the sense of sound. Sound is a form of energy that moves through air, water, and other matter, in waves of pressure. Sound is the means of auditory communication like spoken language. Although the ear is the vertebrate sense organ that recognizes sound, it is the brain and central nervous system that "hears". Sound waves are perceived by the brain through the firing of nerve cells in the auditory portion of the central nervous system. The ear changes sound pressure waves from the outside world into a signal of nerve impulses sent to the brain. The outer part of the ear collects sound. That sound pressure is amplified through the middle portion of the ear and, in land animals, passed from the medium of air into a liquid medium. The change from air to liquid occurs because air surrounds the head and is contained in the ear canal and middle ear, but not in the inner ear. The inner ear is hollow, embedded in the temporal bone, the densest bone of the body. The hollow channels of the inner ear are filled with liquid, and contain a sensory epithelium that is studded with hair cells. The microscopic "hairs" of these cells are structural protein filaments that project out into the fluid. The hair cells are mechanoreceptors that release a chemical neurotransmitter when stimulated. Sound waves moving through fluid push the filaments; if the filaments bend over enough it causes the hair cells to fire. In this way sound waves are transformed into nerve impulses. The nerve impulses travel from the left and right ears through the eighth cranial nerve to both sides of the brain stem and up to the portion of the cerebral cortex dedicated to sound. This auditory part of the cerebral cortex is in the temporal lobe. The part of the ear that is dedicated to sensing balance and position also sends impulses through the eighth cranial nerve, the VIIIth nerve's Vestibular Portion. Those impulses are sent to the vestibular portion of the central nervous system. The human ear can generally hear sounds with frequencies between 20 Hz and 20 kHz(the audio range).
The outer ear is the most external portion of the ear. The outer ear includes the pinna (also called auricle), the ear canal, and the very most superficial layer of the ear drum (also called the tympanic membrane). In humans the only visible portion of the ear is the outer ear. Although the word "ear" may properly refer to the pinna (the flesh covered cartilage appendage on either side of the head), this portion of the ear is not vital for hearing. The outer ear does help get sound (and imposes filtering), but the ear canal is very important. Unless the canal is open, hearing will be dampened. Ear wax (cerumen) is produced by glands in the skin of the outer portion of the ear canal. This outer ear canal skin is applied to cartilage; the thinner skin of the deep canal lies on the bone of the skull. Only the thicker cerumen-producing ear canal skin has hairs. The outer ear ends at the most superficial layer of the tympanic membrane. The tympanic membrane is commonly called the ear drum. The pinna helps direct sound through the ear canal to the tympanic membrane (eardrum).
The framework of the auricle consists of a single piece of yellow fibrocartilage with a complicated relief on the anterior, concave side and a fairly smooth configuration on the posterior, convex side. Human beings localize sound within the central nervous system, by comparing arrival-time differences and loudness from each ear, in brain circuits that are connected to both ears. This process is commonly referred to as EPS, or Echo Positioning System.
III.1. Answer the questions:
What is an ear? Does it have any other meanings?
What does it act for?
Where are the ears located?
What is audition? How does it work?
What parts does an ear consist of?
Which part of the ear really “hears”?
Which parts of an ear are vital for hearing?
How does the brain help hearing?
2. Say whether the following statements are true or false:
Audition is the scientific name for the sense of balance.
The ear is the organ that detects sound. It not only acts as a receiver for sound, but plays a major role in the sense of balance and body position.
Vertebrates have a pair of ears, placed symmetrically on opposite sides of the head.
The ear is the vertebrate sense organ that recognizes sound, although it is the brain and central nervous system that "hears".
The outer part of the ear collects sound.
The hollow channels of the inner ear are filled with liquid.
The auditory part of the cerebral cortex is in the temporal lobe.
The part of the ear that is dedicated to sensing balance and position sends impulses through the eighth cranial nerve.
The outer ear is the most external portion of the ear.
The outer ear helps get sound, but the ear canal is not very important.
3. Continue the sentences:
The ear is….
It not only …
The ear is part …
Vertebrates have …
Although the ear is
The outer part of the ear
The hollow channels of the inner ear
The nerve impulses
This auditory part of the cerebral cortex is….
The part of the ear that is dedicated to …
The outer ear is the most external portion of the ear.
The outer ear …
The framework of the auricle consists of…
Human beings localize…
4. Fill in the blanks with the words from the text:
The …is the organ that detects sound. It not only acts as a … for sound, but plays a major role in the … of balance and body position. The … is part of the auditory system. The word "ear" may be used correctly to describe the entire … or just the visible portion. Vertebrates have a pair of… , placed symmetrically on opposite sides of the head. This arrangement aids in the ability to localize sound… sources. Audition is the scientific name for the … of sound. Sound is a form of energy that moves through air, water, and other matter, in waves of pressure. Sound is the means of auditory communication like spoken language. Although the … is the vertebrate sense organ that recognizes sound, it is the … and central nervous system that "hears". … … are perceived by the brain through the firing of nerve cells in the … … of the central nervous system. The … changes sound pressure waves from the outside world into a signal of … impulses sent to the brain. The outer part of the … collects sound. That … … is amplified through the middle portion of the … and, in land animals, passed from the medium of air into a liquid…. The inner … is hollow, embedded in the temporal … , the densest bone of the body. The … are mechanoreceptors that release a chemical neurotransmitter when stimulated. … waves moving through fluid push the filaments; if the filaments bend over enough it causes the … to fire. In this way sound waves are transformed into … impulses. The nerve ….travel from the left and right … through the eighth cranial … to both sides of the brain stem and up to the portion of the cerebral cortex dedicated to… . This auditory part of the cerebral cortex is in the … lobe.
- the smallest part of a living structure that can operate as an independent structure;
- the part of the ear that is on the outside of the head;
- a part of the brain that is responsible for hearing, memory, and speech;
- the nerve in the scull.
8. Make up one sentence with each word from ex I (3) and II (1). 9. Make up five types of questions on the text. 10. Render the text in English:
Ухо — сенсорный орган у животных и человека служащий для восприятия звука. Ухо человека воспринимает звуковые волны длиной примерно 16 — 20 000 Гц (колебаний в секунду). Анатомическое ухо делится на: наружное ухо, систему среднего уха и внутреннее ухо — лабиринт, в котором различают улитку, преддверие и полукружные каналы. Улитка, наружное и среднее ухо представляют собой орган слуха, в состав которого входит не только рецепторный аппарат, но и сложная звукопроводящая система, предназначенная для доставки звуковых колебаний к рецептору — в неё входят барабанная перепонка и три миниатюрных косточки, «молоточек», «наковальня» и «стремя». Полость внутреннего уха связана с носоглоткой посредством Евстахиевой трубы, через которую выравнивается среднее давление воздуха внутри и снаружи от барабанной перепонки. При изменении внешнего давления иногда «закладывает» уши.
11. Make the written translation of the text. 12. Make a report about a) Human outer ear and culture;
b) Damage to the human ear
c) Outer ear trauma
d) Middle ear trauma
e) Inner ear trauma
f) Non-vertebrate hearing organs
The causes of hearing loss I . 1. The text you are going to read is dedicated to the causes of hearing loss. If you were to deal with that topic, what would you speak about? 2.Pay attention to the following terms used in the text:
to expose – выставлять, подвергать действию ч.-л.;
Exposure to loud noise is the second most common cause of hearing loss. Approximately 30 million Americans are exposed to high intensity noise in their workplace, in one in 4 of these workers (or 7.5 million Americans) a permanent hearing loss will develop. Much can be done to prevent noise-induced hearing loss but little can be done to reverse it. Sometimes a single exposure to loud noise is all that is needed, a single hunting trip without ear plugs. Loud noise damages the hair cells in the inner ear and can cause hearing loss, ear ringing and distortion of sounds. The symptoms of noise induced hearing loss are subtle in the early stages. Hearing loss tends to occur first for high-pitched sounds only. Consequently, the volume of sound heard may be unchanged but the quality of it lessens. Speech may be heard but not completely understood. The presence of background noise can make speech hard to understand. Noise induced hearing loss has been reported to be accompanied by a ringing in the ears (tinnitus) in 23% of subjects. Tinnitus can often be more annoying than the hearing loss itself. Treatment of tinnitus is often unsatisfactory. There has been an association between acoustic trauma (noise induced hearing loss) and Meniere's disease which has been reported in a few research articles and text books. However, more recent literature has shown that acoustic trauma is not a causative factor.
Physical measurements of the sound can determine whether it exceeds dangerous levels, and most factories have access to the necessary equipment. Radio Shack also sells a sound level meter for under $40 which will measure noise levels using the "A" Scale. (This is what the designation dBA refers to -- decibels measured in the A Scale.) However, without noise-measuring equipment, the following basic rules can be followed:
#1. If it is necessary to shout to hear yourself over a noise, the level of the sound can be damaging.
#2. Should ringing in the ears occur after exposure to a loud sound, damage has been done and that sound should be avoided or ear protection used in the future.
#3. If diminished hearing or a sense of fullness in the ears is experienced after noise exposure, the level of that noise is damaging.
There are several federal guidelines for noise exposure.
The NIOSH recommended exposure limit (REL) for occupational noise exposure (85 decibels an 8-hour time-weighted average) was reevaluated using contemporary risk assessment techniques 4000-hertz (Hz) audiometric frequency in the definition of hearing impairment. The new risk assessment reaffirms support for the 85-dBA. With a 40-year lifetime exposure at the 85-dBA REL, the excess risk of developing occupational NIHL is 8%considerably lower than the 25% excess risk at the 90-dBA permissible exposure limit currently enforced by the Occupational Safety and Health Administration (OSHA) and the Mine Safety and Health Administration.
Decibel Levels of Environmental Sounds
Jet Aircraft During Takeoff (at 20 meters)
Tractor Without Cab
Die Forging Hammer
There are also many agents found in industry which can also damage hearing in addition to industrial noise exposure. The most common is tobacco.
Industrial Solvents: The combination of solvents and noise exposure exceeds the damage produced by either also. The effect of solvents is potentiated even more by exposure to ethanol. Organic Solvents found in Industry which are ototoxic include.
--Toluene: Found in paints, thinners, rubbers and in the printing industry.
--Stryene: Found in plastics, rubbers, resins, insulating materials.
--Carbon Disulfide: Found in the textile industry and insecticides.
--Xylene: Found in paint and lacquer industry
Metals: -- Lead may also cause hearing loss
Asphyxiants: Carbon Monoxide
Since there is little that can be done to treat noise induced hearing loss, prevention by avoidance of loud noises is the best course. Compressible foam ear plugs (not water plugs) and ear muffs WHEN FITTED PROPERLY can decrease the noise exposure level by over 20 dB. EAR Classic plugs have a properly fitted noise reduction rating of 29 dB. When given to subjects to fit themselves the average attenuation was found to be 17 dB. Ear plugs and ear muffs are about equally effective. Muffs cost more but can be used in patients with ear canal disease. Muffs are also hot in warm weather.
For hunting, electronic plugs and muffs can be obtained which make surrounding noise louder so game can be heard, but when firing a gun they muffle the loud noise. Many people will not wear ear plugs in a noisy environment because they think it will make it more difficult to hear others talking. Actually the reverse is true. Ear plugs reduce noise most efficiently in the low frequencies, below the speech range. This will increase the signal to noise ratio of the speech and makes it more easily heard.
New research indicates that several types of drugs when taken before or immediately after noise exposure may mitigate the damage to the inner ear. These drugs fall into three categories:
Anti-oxidants: These drugs may be protective based on the theory that one of the mechanisms in noise inducted hearing loss is the generation of free oxygen radicals. Vitamin E given at 10mg/kg/day to 40mg/kg/day in the guinea pig was protective. ; Acetyl-L carnitine a mitrochondrial stabilizer for damage induced by free oxygen radicals, and N-L-acetylcysteine an antioxidant, has been shown to mitigate noise induced hearing loss in the chinchilla.
Glutathione is an antioxadant which has been shown to reduce the damage of noise exposure. Researchers have also found that noise induced hearing loss is characterized by a glutathione deficiency state and increase glutathione levels may be protective. Glutathione monoethylester and in combination with R-N6-phenylisopropyladenosine has also been studied in the chinchilla and has been found to be protective.
Glutamate Receptor Antagonist: These drugs may be protective based on the theory that one of the mechanisms in noise induced hearing loss is the generation of Glutamate which binds to post-synaptic glutamate receptors which leads to degeneration of the neurons. Investigated drugs include: caroverine; carbamathione
Neurotrophins: There is also evidence that neurotrophins (neurotrophin-3) may also be protective.
Remember the most common outcome to noise exposure is a permanent hearing loss. When this occurs the only effective treatment is the use of hearing aids. This is why prevention by avoiding loud noises and wearing ear protectors is so important.