Chapter 20 - Sound

Question 1

What is Pitch?

Answer 1

Pitch is our subjective impression about the “highness” or “lowness” of a tone/the frequency of a tone.

Question 2

What is the relationship between Pitch and Frequency?

Answer 2

Higher frequency will be a higher pitch.
Lower frequency will be a lower pitch.

Question 3

At what hertz is a sound Infrasonic?

Answer 3

Infrasonic is <20 Hz.

Question 4

At what hertz is a sound ultrasonic?

Answer 4

Ultrasonic is >20,000 Hz.

Question 5

Can humans hear infrasonic and ultrasonic sounds?

Answer 5

No! They are too low and high for humans to hear.

Question 6

What is Elasticity?

Answer 6

Elasticity is a property of a material that changes its shape when a force is applied to it then reverts back to its original shape once the force is removed.

Question 7

Is air a good or poor conductor of sound compared to liquids and solids?

Answer 7

Air is a poor conductor compared to liquids/solids.

Question 8

Will sound travel in a vacuum?

Answer 8

No!

Question 9

What happens to the atoms in elastic liquids/solids?

Answer 9

The atoms are relatively close together and respond to each others’ motions quickly. This means they transfer energy with little loss.

Question 10

Does light or sound travel faster?

Answer 10

Light travels faster than sound.

Question 11

What is a Compression?

Answer 11

A compression is a region of increased pressure in a longitudinal (sound) wave. The molecules are pushed against each other and force each other to move.

Question 12

What is a Rarefaction?

Answer 12

A rarefaction is a region of decreased pressure in a longitudinal (sound) wave. The molecules are brought away from each other.

Question 13

At what speed does sound travel through air?

Answer 13

340 m/s

Question 14

What happens to sound energy when it travels through air?

Answer 14

Sound energy changes to thermal energy. This happens faster at a higher frequency. At lower frequencies, sound travels further.

Question 15

What is an Echo?

Answer 15

An echo is a reflection of sound. Sound reflects in the same way that light does.

Question 16

What happens to sound energy that ISN’T carried by the reflected wave?

Answer 16

Sound energy not carried by the reflected wave is carried by the transmitted/absorbed wave.

Question 17

What are Reverberations?

Answer 17

Reverberations are what happen when a sound undergoes multiple reflections after the source has ceased emitting.

Question 18

Why are showers more “lively” and full of sound?

Answer 18

Because of reflected waves! When too much sound is absorbed by the surfaces, the sound produced will be dull and lifeless. This is the opposite of the shower.

Question 19

What are Acoustics?

Answer 19

Acoustics are the study of sound properties.

Question 20

What is a Refraction?

Answer 20

Refractions are when sound waves continue through a medium and bend. They involve a change in wave speed.

Question 21

When do sound waves bend?

Answer 21

Sound waves bend when parts of the wave travel at different speeds. (Ex. uneven winds).

Question 22

What is a Forced Vibration?

Answer 22

A forced vibration is when the vibration of an object is caused by the vibration of a nearby object.

Question 23

What is Natural Frequency and what does it depend on?

Answer 23

Natural frequency is the frequency that an object vibrates at when it’s disturbed and when the disturbing force is removed.
Natural frequency depends on an object’s elasticity and its shape.

Question 24

Through what medium does sound travel fastest?

Answer 24

Sound travels fastest through solids.

Question 25

What is Resonance?

Answer 25

Resonance is when the frequency of forced vibrations on an object matches its natural frequency.

Question 26

What is a Monaural Signal?

Answer 26

A monaural signal is when one speaker sends a compression and the other sends a rarefaction.

Question 27

What are Beats?

Answer 27

Beats are periodic vibrations in the loudness of sound. They are caused by interference.

Question 28

How do you find Beat Frequency?

Answer 28

The difference in frequency is the number of times two objects’ vibrations will be in sync per minute. That is known as Beat Frequency.

Question 29

Are Radio Waves or Sound Waves faster?

Answer 29

Radio Waves! They are always faster than sound waves because they are a type of light wave, and light moves faster than sound.