Tag: human ear

Questions Related to human ear

How does the sound produced by a vibrating object in a medium reach your ear?

how humans hear sound human ear study of sound sound physics

  1. Through electron transfer

  2. Through the vibration of particles

  3. Sound waves don't need a medium

  4. Not enough data

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Correct Option: B
Explanation:

When an object vibrates, it vibrates the neighbouring particles of the medium. These vibrating particles then vibrate to the adjacent particles. Vibrations in an object create disturbance in the medium and consequently compressions and rarefactions.  In this way, vibrations produced by an object are transferred from one particle to another in the form of compressions and rarefactions till it reaches our ear.
Region of high pressure and high density is called compression and region of low pressure and low density in the air is called rarefaction. As the object continues to vibrate, it produces a series of successive compression and rarefaction in the air, thus, propagating sound through the air and finally reaches our ears.

The persistence of hearing for human beings is not more than

how humans hear sound human ear study of sound sound physics

  1. 1 s

  2. $\displaystyle \frac{1}{5}:s$

  3. $\displaystyle \frac{1}{10}:s$

  4. $\displaystyle \frac{1}{2}:s$

Show answer
Correct Option: C
Explanation:

The sensation of hearing of any sound persists in our brain for 0.1s.This is called the persistence of hearing.

so the answer is C.

Calculate he minimum distance to hear an echo.(taking the velocity of sound in air to be $330 {ms}^{-1}$)

how humans hear sound human ear study of sound sound physics

  1. 12.8 m

  2. 24 m

  3. 8.6 m

  4. 17.5 m

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Correct Option: D

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 mm$^{2}$ and the area of stirrup is about 3.2 mm$^{2}$. 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 $3\times10^{-2}$ Pa from its normal equilibrium pressure value which is wqual to $10^{5}$ 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 $1.42\times10^{5}$ Pa. Bulk modulus of fluid is $2.18\times10^{9}$ Pa.


Find the pressure amplitude of given sound wave in the fluid of inner ear. 

how humans hear sound human ear study of sound sound physics

  1. 0.03 Pa

  2. 0.04 Pa

  3. 0.3 Pa

  4. 0.4 Pa

Show answer
Correct Option: D
Explanation:

Given :   Area of stirrup        $A _s = 3.2 mm^2     = 3.2\times 10^{-6}$ $m^2$

             
  Area of eardrum     $A = 43  mm^2  = 43 \times 10^{-6} m^2$

  Pressure amplitude at eardrum    $P _o =  3 \times 10^{-2}$  Pa

Force exerted by sound wave in air on eardrum       

$F =  P _o A = 3 \times 10^{-2} \times 43 \times 10^{-6}   = 129 \times 10^{-8}$N

According to question , force exerted on eardrum is equal to force exerted by ossicles on the inner ear.

Let pressure amplitude in the fluid of inner ear be  $p' _o$

$\therefore$    $p' _o  = \dfrac{F}{A _s}  =  \dfrac{129 \times10^{-8}}{3.2 \times 10^{-6}}   = 0.4$ Pa