What is Hearing

            What is Hearing 

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Hearing range describes the range of frequencies that can be heard by humans or other animals, though it can also refer to the range of levels. The human range is commonly given as 20 to 20,000 Hz, although there is considerable variation between individuals, especially at high frequencies, and a gradual loss of sensitivity to higher frequencies with age is considered normal. Sensitivity also varies with frequency, as shown by equal-loudness contours. Routine investigation for hearing loss usually involves an audiogram which shows threshold levels relative to a normal.

Several animal species are able to hear frequencies well beyond the human hearing range. Some dolphins and bats, for example, can hear frequencies over 100 kHz. Elephants can hear sounds at 14–16 Hz, while some whales can hear infrasonic sounds as low as 7 Hz.

In humans, sound waves funnel into the ear via the external ear canal and reach the eardrum (tympanic membrane). The compression and rarefaction of these waves set this thin membrane in motion, causing sympathetic vibration through the middle ear bones (the ossicles: malleus, incus, and stapes), the basilar fluid in the cochlea, and the hairs within it, called stereocilia. These hairs line the cochlea from base to apex, and the part stimulated and the intensity of stimulation gives an indication of the nature of the sound. Information gathered from the hair cells is sent via the auditory nerve for processing in the brain.

The commonly stated range of human hearing is 20 to 20,000 Hz.                      Under ideal laboratory conditions, humans can hear sound as low as 12 Hz  and as high as 28 kHz, though the threshold increases sharply at 15 kHz in adults, corresponding to the last auditory channel of the cochlea.   The human auditory system is most sensitive to frequencies between 2,000 and 5,000 Hz.                   Individual hearing range varies according to the general condition of a human's ears and nervous system. The range shrinks during life, usually beginning at around the age of eight with the upper frequency limit being reduced. Women lose their hearing somewhat less often than men. This is due to a lot of social and external factors. For example, men spend more time in noisy places, and this is associated not only with work but also with hobbies and other activities. Women have a sharper hearing loss after menopause. In women, hearing decrease is worse at low and partially medium frequencies, while men are more likely to suffer from hearing loss at high frequencies.

Hearing Ability of Birds

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The hearing range of birds is most sensitive between 1 kHz and 4 kHz, but their full range is roughly similar to human hearing, with higher or lower limits depending on the bird species. No kind of bird has been observed to react to ultrasonic sounds, but certain kinds of birds can hear infrasonic sounds. "Birds are especially sensitive to pitch, tone and rhythm changes and use those variations to recognize other individual birds, even in a noisy flock. Birds also use different sounds, songs and calls in different situations, and recognizing the different noises is essential to determine if a call is warning of a predator, advertising a territorial claim or offering to share food."

"Some birds, most notably oilbirds, also use echolocation, just as bats do. These birds live in caves and use their rapid chirps and clicks to navigate through dark caves where even sensitive vision may not be useful enough."

Pigeons can hear infrasound. With the average pigeon being able to hear sounds as low as 0.5 Hz, they can detect distant storms, earthquakes and even volcanoes. This also helps them to navigate.

Basic types of hearing loss:

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Hearing loss, Presbycusis

 

Total or significant loss of hearing.

Deafness is usually the result of inner ear or nerve damage. It may be caused by a congenital defect, injury, disease, certain medication, exposure to loud noise or age-related wear and tear.

• Conductive hearing loss.

• Sensorineural hearing loss.

• Mixed hearing loss.

Sensorineural Hearing Loss

Sensorineural loss is the most common type of hearing loss. It can be a result of aging, exposure to loud noise, injury, disease, certain drugs or an inherited condition.

Types of deafness

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• Sensorineural deafness, or nerve deafness as it's sometimes called, is a hearing loss in the inner ear. This usually means that the cochlea isn't working effectively. ...

• Conductive deafness means that sound can't pass efficiently through the outer and middle ear into the inner ear.

AYURVEDIC REMEDIES 

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Fenugreek seeds half teaspoon.

One spoon pure desi ghee.

Ghee must be pure.

Heat both in a brass bowl,

Put one drop by one in the ear while it is slightly warm.

very good result if put in ear before sleeping.

This cures every ear disease.

          OR

Desi cow's calf's urine 

fresh calf urine daily,one drop in both ears,

If there is any pain in the ear then it will be cured only by inserting it once.What if you are hard of hearing?In a few days he will also start getting better.

If you would behave the real thing.Amazing results will come.

       Thanks to all 

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