Draw a labeĺl diagram of human ear.Explain it's working?
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Is a diagram of the human ear. The outer ear consists of the visible part of the ear or pinna, the external auditory canal (meatus), and the tympanic membrane (tympanum) or eardrum. The human pinna is formed primarily of cartilage and is attached to the head by muscles and ligaments. The deep central portion of the pinna is called the concha, which leads into the external auditory canal, which in turn leads to the tympanic membrane.Only mammals have pinnae and only some have mobile pinnae. The pinnae of humans and primates have no useful muscles and are therefore relatively immobile. Mobile, and to some extent, immobile pinnae help in localising sounds by funnelling them towards the external canal.The pinnae also help in distinguishing between noises originating in front of and behind the head, and in providing other types of filtering of the incoming sound wave. In addition, the concha and external auditory canal effectively enhance the intensity of sound that reaches the tympanic membrane by about 10 to 15 dB. This enhancement is most pronounced for sounds in the frequency range of roughly 2 to 7 kHz and so, in part, determines the frequencies to which the ear is most sensitive. Finally, the outer ear protects the tympanic membrane against foreign bodies and changes in humidity and temperature.
The external auditory canal extends about 2.5 cm inside the skull before it ends in the tympanic membrane. Sound travels down the meatus and causes the tympanic membrane to vibrate. The tympanic membrane is thin and pliable so that a sound, consisting of compressions and rarefactions of air particles, pulls and pushes at the membrane moving it inwards and outwards at the same frequency as the incoming sound wave. It is this vibration that ultimately leads to the perception of sound. The greater the amplitude of the sound waves, the greater the deflection of the membrane. The higher the frequency of the sound, the faster the membrane vibrates.
On the other side of the tympanic membrane is the middle ear (Figure 1) which is an air-filled chamber containing three interlocking bones called ossicles. These are the smallest bones in the body and function to transmit the vibrations caused by auditory stimulation at the tympanic membrane to the inner ear. The bones are called the malleus (Latin for ‘hammer’), the incus (‘anvil’) and the stapes (‘stirrup’). The ossicle attached to the tympanic membrane is the malleus, which forms a rigid connection with the incus. The incus forms a flexible connection with the stapes. The flat bottom portion of the stapes, the footplate, is connected to the oval window (a second membrane covering a hole in the bone of the skull). In response to sound, the inward-outward movement of the tympanum displaces the malleus and incus and the action of these two bones alternately drives the stapes deeper into the oval window and retracts it, resulting in a cyclical movement of fluid within the inner ear.
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