Tag: study of sound

Questions Related to study of sound

State whether given statement is True or False :
There is no possibility of having mixed hearing loss with both conductive and sensori-neural element.

how humans hear sound human ear study of sound sound physics

  1. True

  2. False

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Correct Option: B
Explanation:

It is a false statement. It is possible to have a mixed hearing loss.

Why do we lose hearing while yawning?

how humans hear sound human ear study of sound sound physics

  1. Muscles around middle ear contracts

  2. Muscles around middle ear expands

  3. Muscles around inner ear contracts

  4. Muscles around inner ear expands

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Correct Option: A
Explanation:

Muscles around middle ear contracts while yawning. So, we are not able to hear while yawning.

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

Show answer
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

In order to produce an echo, the minimum distance between the source of the sound and the reflecting body should be :

physics study of sound conditions for hearing echo echo reflection of sound and echo ultrasound and its applications

  1. 14 m

  2. 16 m

  3. 17 m

  4. 20 m

Show answer
Correct Option: C
Explanation:

As the sensation of sound persists in our brain for about 0.1 s, to hear a distinct echo the time interval between the original sound and the reflected one must be at least 0.1 s. If we take the speed of sound to be 344 m/s at a given temperature, say at 22 $^0C$ in air, sound must go to the obstacle and reach back the ear of the listener on reflection after 0.1s.
 
Hence, the total distance covered by the sound from the point of generation to the reflecting surface and back should be at least (344 m/s) ×0.1 s = 34.4 m. Thus, for hearing distinct echoes, the minimum distance of the obstacle from the source of sound must be half of this distance. I.e., $\frac{34.4}{2} \approx 17 \,m$

The minimum distance between the source of a sound and reflecting body should be 17 m for the formation of an echo. True or false

[consider the medium to be air]

physics study of sound conditions for hearing echo echo reflection of sound and echo ultrasound and its applications

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

As the sensation of sound persists in our brain for about 0.1 s, to hear a distinct echo the time interval between the original sound and the reflected one must be at least 0.1 s. If we take the speed of sound to be 344 m/s at a given temperature, say at 22 $^0C$ in air, sound must go to the obstacle and reach back the ear of the listener on reflection after 0.1s.
 
Hence, the total distance covered by the sound from the point of generation to the reflecting surface and back should be at least (344 m/s) ×0.1 s = 34.4 m. Thus, for hearing distinct echoes, the minimum distance of the obstacle from the source of sound must be half of this distance. I.e., $\frac{34.4}{2} \approx 17 \,m$

Echo can be heard if 

physics study of sound conditions for hearing echo echo reflection of sound and echo ultrasound and its applications

  1. the minimum distance between the source of sound and the obstacle is $17m$

  2. the obstacle is rigid and hard.

  3. both A and B hold

  4. none of A and B hold

Show answer
Correct Option: C
Explanation:

The options are the conditions for an echo to be produced. The obstacle should be rigid at a minimum distance of $17m$ for an echo to be produced.

The minimum distance in air between the observer and the obstacle for an echo to be heard clearly at temperatures higher than ${25}^{0}C$ is :

physics study of sound conditions for hearing echo echo reflection of sound and echo ultrasound and its applications

  1. less than $17.2m$

  2. more than $17.2m$

  3. equal to $17.2m$

  4. unpredictable

Show answer
Correct Option: B
Explanation:

The minimum distance in air between the observer and the obstacle for an echo to be heard clearly at temperatures higher than ${25}^{0}C$ is more than $17.2m$. The speed of sound increases with rise in temperature.