Sound

Front 1

What produces all the sounds that we hear?

Back 1

Vibrations.

Sound is produced when matter (whether it is solid, liquid or gas) vibrates.

Front 2

What is sound?

Back 2

Sound occurs when matter vibrates (moves back and forth quickly).

Front 3

How do we speak?

Back 3

Our vocal chords vibrate. Air from the lungs travels past them and makes them vibrate

Front 4

How does a bell make a sound?

Back 4

When it is struck it vibrates and pushes the air around it. As it vibrates to the right air molecules are squeezed together on the right side of the bell. As it vibrates to the left, air molecules on the right side expand while the air molecules on the left side of the bell are squeezed together.

Front 5

What do we call air molecules that are squeezed together and what do we call air molecules that are spread apart.

Back 5

Air molecules that are squeezed together are called compressions.

Air molecules that are spread apart are called rarefactions.

Front 6

Can sound travel in a vacuum?

Back 6

No. Sound can only occur when matter vibrates. There is no sound in space as it is nearly void of matter.

Front 7

When you toss a pebble into a pond a wave moves up and down as it spreads outward. What do we call this up and down motion?

Back 7

A transverse wave.

Front 8

If you pull on one end of a spring coil the wave will move along the coil as it transfers energy from one coil to the next. What is this wave called?

Back 8

A longitudinal wave.

Front 9

How does sound travel?

Back 9

Like a longitudinal wave. When air molecules move they transfer energy to the next air molecule. Although the sound has moved a long way each air molecule has only moved a little way.

Front 10

Does the strength of the sound wave stay constant?

Back 10

No, it weakens as it travels further away from the original object.

Front 11

What will happen when you strike a tuning fork and place it in a glass of water?

Back 11

The water will splash. Sound waves from the fork vibrate in the water causing it to move.

Front 12

How is a sound wave made by, for example, a drum?

Back 12

When it is struck the head of the drum vibrates. This vibration causes the air molecules around it to vibrate and produce a sound wave that travels away from the drum in all directions.

Front 13

Who was the Irish scientist who discovered that sound waves need a medium to travel in?

Back 13

Robert Boyle (1627-91)

Front 14

How could Beethoven still hear music when he had lost all his hearing.

Back 14

He placed a stick between his teeth and rested it on the piano. The sound wave travelled through the stick to his inner ear.

Front 15

Imagine a picture of a sound wave. What is the high part of the wave called and what is the low part called?

Back 15

The high part is called the peak or crest and the low part is called a trough.

Front 16

Still imagining the sound wave, what is a complete movement from peak to trough and back to peak called?

Back 16

A cycle.

Front 17

What is the frequency of a sound?

Back 17

It is the number of cycles that pass in one second. So, if an object vibrates 10 times per second, its frequency would be ten cycles per second (10cps).

Front 18

What is the connection between frequency and wavelength?

Back 18

A wave with a lower frequency has a longer wavelength. A wave with a higher frequency has a shorter wavelength.

Front 19

What type of wave length and frequency produces low-pitched sounds?

Back 19

A wave with a lower frequency and with a longer wavelength produces low-pitched sounds.

Front 20

What type of wave length and frequency produces high-pitched sounds?

Back 20

A wave with a higher frequency and a shorter wavelength produces high-pitched sounds.

Front 21

What unit is used to measure frequency?

Back 21

Hertz (Hz). One cycle equals one hertz.

Front 22

What is the intensity of a sound?

Back 22

The intensity is the strength of the sound. Sound waves can carry different amounts of energy and the intensity determines how loud a sound is.

Front 23

What determines the intensity of a sound?

Back 23

The height of the soundwave. A sound wave that carries a great amount of energy has a high intensity. A sound wave that carries a small amount of energy has a low intensity.

Front 24

What does amplitude measure?

Back 24

Amplitude measures the height of a wave's crest. It, therefore, measures the intensity and loudness of a sound.

Front 25

What causes different frequencies?

Back 25

Objects vibrate at different rates and this leads to different frequencies.

Front 26

In what range can humans produce sounds?

Back 26

Within a range of about 85 to 1,100 Hertz. That is between 85 times a second and 1,100 times a second.

Front 27

What were Hertz named after?

Back 27

Heinrich Hertz (1857 to 1894). A German physicist who was the first to produce and detect radio waves.

Front 28

Can sound travel through air, water and solids?

Back 28

Yes; but they travel at different speeds through these mediums.

Front 29

Does the air temperature affect the speed of sound through the air?

Back 29

Yes. Sound travels a little faster through hot air than through cold air.

Front 30

What, in general terms, is the speed of sound?

Back 30

At 20 °C (68 °F), the speed of sound is 343 meters per second. This equates to 1,236 km per hour (768 mph), or about one km in three seconds and about one mile in five seconds.

Front 31

Does sound travel faster through water or air?

Back 31

It travels five times faster in water than it travels through air.

Front 32

Why does sound travel faster through water than air?

Back 32

The molecules in a liquid are closer together than in air which enables the energy to be transferred quicker between molecules.

Front 33

Does sound travel faster through solids or through air?

Back 33

It travels faster through solids. This is because the molecules are closer together in solids. It travels eighteen times faster through steel than through air.

Front 34

How do we hear the sound of, for example, a bell.

Back 34

The bell vibrates causing air molecules around the bell to vibrate. These molecules cause the air molecules next to them to start vibrating. These vibrations quickly spread and reach an ear.

Front 35

How many parts does the human ear consist of?

Back 35

Three parts; the outer ear, middle ear and inner ear,

Front 36

What do we call the part of the outer ear that we can see?

Back 36

The auricle. It collects and directs sound waves into the ear.

Front 37

What happens to a sound wave after it has gone through the auricle?

Back 37

They vibrate along the auditory canal where moving air molecules press on the eardrum and make it vibrate.

Front 38

What does the eardrum press on to?

Back 38

Three tiny bones (hammer, anvil and stirrup) that amplify the sound and vibrate against the thin membrane at the entrance to the inner ear.

Front 39

What happens in the inner ear?

Back 39

The movement of the membrane creates pressure waves in the fluid that is located inside a narrow tube called the cochlea. Here sound waves are transferred into electrical signals.

Front 40

What happens to the electrical signals that come from the cochlea?

Back 40

They travel along the auditory nerve to the brain where we hear the sound.

Front 41

What do we call the strength of a sound?

Back 41

The strength of a sound is its intensity. The greater amount of energy carried by the sound wave the higher its intensity.

Front 42

What is amplitude?

Back 42

The intensity and loudness of a sound is called its amplitude. It is measured in decibels.

Front 43

Who is a decibel named after?

Back 43

Alexander Graham Bell (1847-1922) who was responsible for many inventions, including the telephone.

Front 44

What does amplitude measure?

Back 44

Amplitude measures the height of a wave's crest. a sound wave may have the same frequency and wavelength but different wave heights.

Front 45

At what decibel levels can sound be painful?

Back 45

At about 90 decibels. Over 130db your hearing can be damaged.

Front 46

What sound has a greater intensity - a loud sound or a soft sound.

Back 46

A loud sound has a greater intensity than a soft sound.

Front 47

How does the intensity of a sound determine how far away the sound can be heard?

Back 47

The greater the intensity of sound the greater distance the sound can be heard.

Front 48

What is pitch?

Back 48

Pitch is the high or low quality of a sound. Vibrations at slow rate produce a low sound whereas vibrations at a fast rate produce a high sound.

Front 49

What are the different types of musical instruments?

Back 49

String, wind, brass and percussion

Front 50

How do musical instruments make sound?

Back 50

Musical instruments make sound by causing air to vibrate

Front 51

How can, for example, a guitar, make different sounds?

Back 51

It has strings of differing thickness that vibrate at different frequencies. Plucking a thin string produces a high-pitched sound and plucking a thick string produces a low-pitched sound.

Front 52

What type of surface creates the clearest echoes?

Back 52

The clearest echoes are produced when sounds bounce back from hard smooth surfaces.

Front 53

Can you hear an echo if you are close to the surface?

Back 53

No. If you are too close to the surface the sound waves reflect quickly and you do not hear a separate echo. Echoes can only be heard from surfaces that are at least 17m away.

Front 54

In what ways do sound waves 'bounce' off objects?

Back 54

In the same way that a ball thrown against a wall does.

Front 55

If an object does not reflect sound what does it do to the sound?

Back 55

Some objects absorb sound. Soft, spongy items are the best at absorbing sound.

Front 56

Where will your voice sound loudest. In an empty room or in a room full of furniture?

Back 56

In an empty room as there is nothing to absorb the sound and plenty of hard surfaces to reflect the sound.

Front 57

What is the study of how sound is transmitted called?

Back 57

Acoustics.

Front 58

What should an auditorium do with sound?

Back 58

Auditoriums should reflect sound yet control echoes.

Too much reverberation (echoes that bounce back and forth) makes the sound confusing and not enough reflection makes the sounds dull.

Front 59

In what frequency range can humans hear sounds?

Back 59

In the range 20-20,000 Hertz.

Front 60

What are sound waves with frequencies above 20,000 Hertz called.

Back 60

Ultrasound

Front 61

What can ultrasound be used for?

Back 61

Ultrasound can be used to locate objects, measure distances and see inside the human body.

Front 62

What do we call the instrument that beams ultrasound waves into a human body.

Back 62

A transducer.

Front 63

How are ultrasounds used in medicine?

Back 63

The images are used to evaluate blood vessels and organs, to detect tumours and to view an unborn baby.

Front 64

How are ultrasound images produced?

Back 64

They record the echoes. The strength of the echo is determined by the tissue's structure and they produce images with varying degrees of brightness.

Front 65

What do we call echoes that are used to determine location and distance under water?

Back 65

Sonar.

SOund Navigation And Ranging.

Front 66

How does Sonar work.

Back 66

Ultrasound waves are sent out from a ship. When they strike an object (fish, wreck, submarine or seafloor) they send back an echo. Distance can be determined by measuring the time it takes for a sound to reach an object.

Front 67

What is seismology?

Back 67

Seismology is the study of the movement of the earth's crust.

Front 68

What is a seismograph?

Back 68

A seismograph records the sound waves travelling through the ground.

By studying these sound waves earthquakes may be predicted.