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Byju's Answer
Standard X
Biology
Ear
What is the f...
Question

What is the function of the part labelled as ‘a’ in the given figure?

A
Transmits sound waves from ear canal to ear ossicles
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B
Transmits sound waves from pinna to eardrum
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C
Amplification of sound waves
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D
Equalising the pressures on either side of the eardrum
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Solution

The correct option is B Transmits sound waves from pinna to eardrum
The outer ear consists of pinna and external auditory meatus or canal. The part labelled as ‘a’ in the given figure is external auditory meatus. It is lined by fine hairs and wax secreting glands internally. It extends from the pinna to the eardrum (tympanic membrane). The auditory canal directs the sound waves received by pinna to eardrum (tympanic membrane).

Transmitting the sound waves from ear canal or external auditory meatus to ear ossicles is the function of eardrum (tympanic membrane).
Amplification of sound waves is the function of ear ossicles.
Equalising the pressures on either side of the eardrum is the function of the Eustachian tube.

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Q. Match column I with column II and select the correct option from the given codes.
Column IColumn II
A. Pinna(i) Collects vibrations in the air which produces sound
B. Ear canal(ii) Passage for sound wave from pinna to ear drum
C. Tympanic membrane(iii) Transfers sound wave to ear ossicles
D. Ear ossicles(iv) Increases the efficiency of transmission of sound waves to the inner ear
E. Cochlea(v) Has hearing receptors
F. Eustachian tube(vi) Equalises the pressure on both sides of ear drum
G. Auditory nerves(vii) Impulse transfer from organ of Corti to auditory cortex in temporal lobe of cerebrum

Q.

Match the following parts of the ear with their functions.

Parts of the earFunctions1. PinnaA. Vibrates and transmits sound waves to the ossicles2. TympanumB. Sends the audio impulses to the cerebrum3. Ear ossiclesC. Collects sound and directs it into the ear4. Auditory nerveD. Amplifies and transmits the sound to cochlea


Q.
When a sound wave enters the ear, it sets the eardrum into oscillation, which in turn causes oscillation of 3 tiny bones in the middle ear called ossicles. This oscillation is finally transmitted to the fluid filled in inner portion of the ear termed as inner ear, the motion of the fluid disturbs hair calls within the inner ear which transmit nerve impulses to the brain with information that a sound is present. The three bones present in the middle ear are named as hammer, anvil and stirrup. Out of these the stirrup is the smallest one and this only connects the middle ear to inner ear as shown in the figure below. The area of stirrup and its extent of connection with the inner ear limits the sensitivity of the human ear. Consider a person's eat whose moving part of the eardrum has an area of about 43 mm2 and the area of stirrup is about 3.2 mm2. The mass of ossicles is negligible. As a result, force exerted by sound wave in air on eardrum and ossicles is same as the force exerted by ossicles on the inner ear. Consider a sound wave having maximum pressure fluctuation of 3×10−2 Pa from its normal equilibrium pressure value which is wqual to 105 Pa. Frequency of sound wave is 1200 Hz.
Data: Velocity of sound wave in air is 332 m/s. Velocity of sound wave in fluid (present in inner ear) is 1500 m/s. Bulk modulus of air is 1.42×105 Pa. Bulk modulus of fluid is 2.18×109 Pa.


Find the pressure amplitude of given sound wave in the fluid of inner ear.
Q. Trace the route of sound waves from outer ear to inner ear.
Q. Sound waves from outside are collected by which part of the ear?
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Standard X Biology
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