Physics · Science General

Acoustics and Sound Waves

2,160 Questions

Acoustics and sound waves deal with mechanical vibrations traveling through media like air and water. Key concepts include wave reflection, beats, echoes, the Mach number, and infrasound. These physics fundamentals are regularly tested in general science sections of multiple competitive exams.

Sound wave propagationEchoes and reflectionWave interferenceMach numberInfrasound frequency

Acoustics and Sound Waves Questions

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.

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

If the ceiling of a cineural is made flat, what will happen

  1. no sound will be audible at all.

  2. picture will vanish.

  3. sound will not reach properly to every person.

  4. picture will not be clear to everyone
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ceiling in a cinema hall is made curve so that the sound of music, dialogue etc must reach evenly to all the audience.
So that the sound after reflection from curved surface reaches all corners of the hall evenly.

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

Excessive reverberation in any auditorium/hall is not desirable because :

  1. sound becomes blurred

  2. sound become distorted

  3. sound remains same

  4. both A and B
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Excessive reverberation in any auditorium or hall is not desirable because the sound becomes blurred and distorted. So the reverberation needs to be reduced.

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

Megaphones or loudhailers, horns, musical instruments such as trumpets and  shehnais, are all designed to ______.

  1. send sound in a particular direction without spreading it in all directions.

  2. send sound in a particular direction spreading it in all directions.

  3. collect sound from all directions spreading it in all directions.

  4. all of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Megaphones or loudhailers, horns, musical instruments such as trumpets and shehnais, are all designed to send sound in a particular direction without spreading it in all direction.
In these instruments, a tube followed by a conical opening reflects sound successively to guide most of the sound waves from the source in the forward direction towards the audience.

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

In an auditorium or big hall excessive reverberation is highly _______.

  1. undesirable

  2. desirable

  3. zero

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

Sound created in a big hall will persist  by repeated reflection from the walls until it is reduced to a value where it is no longer audible. The repeated reflection that results in this persistence of sound is called reverberation. In an auditorium or big hall excessive reverberation is highly undesirable.

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. Otherwise

  1. multiple echos will enhance the sound quality

  2. multiple echos will interfere with the original sound

  3. multiple echos will not interfere with the original sound

  4. both A and B
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Reverberation time of a hall used for speeches should be very short because multiple echoes will interfere with the original sound. So, reverberation time is reduced to avoid multiple echoes.

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 without curtains

  3. high reverberation without curtains

  4. both A and B
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

There is more reverberation in rooms with curtains so we can hear sound more clearly.

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 of them
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A certain amount of reverberation may improve the quality of sound. However, excessive reverberation is sometimes undesirable as it interferes with the original sound and hence makes the speech or music indinstict