Tag: study of sound

Quizzes (14) Questions (314)

Questions Related to study of sound

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

What should be the minimum distance between the listener and the reflector to hear an echo of sound propagating with a speed $v\   m s^{-1}$?

  1. $v/10$ m
  2. $10 v$ m
  3. $v/20$ m
  4. $20v$ m
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
if there is a sound reflector at a distance d from the source, then the time interval between original sound and its echo at the site of the source is given as $T=\dfrac { 2d }{ v } $
 $d=\dfrac { v\times t }{ 2 } = \dfrac { v\times 1 }{ 2\times 10 } $ as Time = 0.1 s.
Hence, $d=\dfrac { v }{ 20 }$.

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

A man starts from rest and moves with constant acceleration towards a hill which is $648 m$ away. He fires a gun at the instant of starting and hears its echo after $4$ seconds. Velocity of sound in air is $320 m/s$

  1. His acceleration is $1m/s^{2}$
  2. His acceleration is $2m/s^{2}$
  3. His velocity at the instant of hearing echo is $4 m/s$
  4. His velocity at the instant of hearing echo is $8 m/s$
Reveal answer Fill a bubble to check yourself
B,D Correct answer
Explanation

Using s = 0.5 * a * t^2, the distance the man travels is 0.5 * a * 16 = 8a. The sound travels to the hill (648 m) and back to the man (648 - 8a). Total distance = 648 + (648 - 8a) = 1296 - 8a. Also, distance = v_sound * t = 320 * 4 = 1280. 1296 - 8a = 1280 implies 8a = 16, so a = 2 m/s^2. Velocity v = a * t = 2 * 4 = 8 m/s.

Multiple choice physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

Why do we hear more clearly in a room with curtains than in a room without curtains?

  1. sound is absorbed by the curtains.

  2. less reverberation

  3. a and b

  4. none
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

We hear more clearly in a room with curtains than of that in a room without curtains because curtains act as a good sound absorbent. So, they absorb the sound produced in the room and thus, prevent unwanted echo of sound due to refraction. Otherwise, the inter lapping of sounds would be most undesirable as we won't be able to hear clearly.

Multiple choice physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

_________ is a device which is based on multiple reflection and isused for sending amplified sound in a particular direction.

  1. Bulb horn

  2. Megaphone

  3. Ear trumpet

  4. all
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Megaphone is based on multiple reflection of sound. It is a horn shaped tube designed to send amplified sound in a particular direction. It is also called Loud hailer.

Multiple choice physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

Which of the following device does not work on the multiple reflections of sound waves?

  1. stethoscope

  2. hydrophone

  3. soundboard

  4. megaphone
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Stethoscope is a medical diagnostic instrument based on multiple reflection of sound waves.
This is used by doctors for listening to the sounds produced inside the body.
Sound board is a concave rigid surface which is placed behind the speaker in a big hall so that his words can be heard clearly even by the people sitting away from the stage.

Multiple choice physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

The persistence of audible sound due to the successive reflections from the surrounding objects even after the source has stopped to produce that sound is called

  1. reflection

  2. echo

  3. reverberation

  4. rarefaction
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

According to the definition of reverberation, it is the persistence of audible sound due to the successive reflections from the surrounding objects even after the source has stopped to produce that sound.

Multiple choice physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

Reverberation time of a hall used for speeches should be very short. Why?

  1. Multiple echos will enhance the sound quality.

  2. Multiple echos will interfere with the original sound

  3. Both a and b

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Reverberation time of a hall used by speeches should be very small so that due to multiple reflection of sound, we will hear the same voice again and again distracting our concentration to hear important points of the speech. If we hear same sound many times it will irritate us.

Multiple choice physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

Curved surfaces which are used in big hall to direct the sound waves towards the people sitting in a hall are known as:

  1. megaphone

  2. hydrophone

  3. bulb horn

  4. none of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sound boards are the curves surfaces (concave) which are used in a big hall to direct the sound waves towards the people sitting in a hall. The source of sound is placed at the focus of the sound board.

Multiple choice physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

Mark the correct statement .
i) rock music also becomes less pleasing with excessive reverberation.
ii) excessive reverberation is desirable in case of orchestral and choral music.
iii) excessive reverberation makes the speech of a person indistinct.

  1. i, ii

  2. ii, iii

  3. i, iii

  4. all
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Reverberation is the phenomenon of persistence of sound after it has been stopped as a result of multiple reflections from surfaces such as furniture, people, air etc. within a closed surface. But the excessive reverberation is undesirable as the sound produced will continue to be heard repeatedly while the next sound being sent forth. This is unpleasant to hear and there is no clarity of sound.

So, all the statements are correct.

Multiple choice physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

A device based on multiple reflection used as hearing aid.

  1. bulb horn

  2. ear trumpet

  3. megaphone

  4. all
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ear trumpet or hearing aid is used by the persons who are hard of hearing. The sound waves received by the wide end of the trumpet are reflected into a much narrower area.