Sound Waves Doddle

Question 1

What is sound?

Answer 1

Sound is a form of energy. Sound can be described by its intensity. This is how loud or soft it is. Sound can also be described by its pitch. This is how high or low it is.

Question 2

What causes sound?

Answer 2

Sounds are made when an object vibrates. Sound travels because the vibrating object makes nearby particles vibrate. Sound needs a medium to travel through it cannot pass through a vacuum.

Question 3

How does sound travel through air?

Answer 3

Stage 1
When the tuning fork is struck, it vibrates. The movement pushes the air particles next to the fork.
Stage 2
The particles pushed by the vibrating metal, push the particles next to them. This forms a wave which travels through the air particles.

Question 4

What are longitudinal waves?

Answer 4

Sound travels as waves made by vibrating air particles. Sound waves are an example of longitudinal waves. In a longitudinal wave, the particles vibrate back and forth, of the wave. Think about the hairs on this cat vibrating backwards and forwards, as sound waves from the speaker pass by.

Question 5

What do longitudinal waves look like?

Answer 5

A slinky can be used to model longitudinal waves, by moving one end of the slinky left and right. The wave travels away from the source. The direction of the wave is parallel to the movement of the source. In each longitudinal wave, the coils do not travel horizontally; each coil of the slinky just vibrates left and right.

Question 6

What is the wavelength of a longitudinal wave?

Answer 6

The wavelength of any wave is the distance between two matching points on neighbouring waves.the wavelength is the same whichever two matching points are used to measure this. Distance.

Question 7

‘Seeing’ sound waves

Answer 7

If we connect an mo3 player to a speaker, we can all hear the sound produced. If we also connect an oscilloscope to the mp3 player, then we can ‘see’ the sound waves.

Question 8

Loudness and Amplitude

Answer 8

A sound can be quiet or loud on an oscilloscope trace, the loudness of a sound is shown by the height of the wave. This is called the amplitude. The larger the amplitude of the wave on the trace, the louder the sound.

Question 9

Pitch and frequency

Answer 9

On an oscilloscope trace, the pitch of a sound is shown by how many waves there are. This is called the frequency. The greater the frequency of waves on the trace the higher pitch.

Question 10

Units of frequency

Answer 10

The frequency of sound waves is measured in (Hz). One hertz is the same as one cycle per second.
1 cycle in 2.5 seconds = 0.4Hz
4 cycles in 5 seconds = 0.8Hz

Question 11

Speed of sound

Answer 11

Speed = distance/time

Question 12

Energy transfer

Answer 12

When the cymbals crash there is a transfer of kinetics energy form the cymbal to the air particles. When the sound waves reach the ear, there is a transfer of kinetic air particles to the eardrum.

Question 13

Sounds in different material

Answer 13

Sound needs a substance through which not travel because it travels by making particles vibrate. Sound waves travel fastest through solids. The particles in a solid are closer together than in a gas and more tightly bounded than in a liquid. This means vibrations are more easily passed from particle to particle so sound travels faster.

Question 14

What is the speed of sound in different materials?

Answer 14

Air at 0°C = 330m/s
Air at 30°C = 350m/s
Water = 1450m/s
Concrete = 500m/s
Steel = 600m/s

Question 15

The absorption of sound

Answer 15

The sound waves are absorbed by the material. Soft, porous, uneven materials like curtains, carpets and foam absorb most sound. These are good sound insulators.

Question 16

Reflected sound

Answer 16

When a sound wave meets a hard, flat, smooth surface the sound wave is reflected back from the surface. This is called an echo.

Question 17

Sound waves are produced in loud speakers

Answer 17

Loudspeakers turn electricity into sound. The loudspeaker uses a coil that can slide over a permanent magnet. A paper cone is attached to the coil. As electricity flows back and forth in the cables, the coil and the attached cone move back and forth at the same frequency. This vibrates the air in front of the speaker, creating sound waves. The greater the vibration of the cone, the louder the sound.

Question 18

Detective sound using microphones

Answer 18

Microphones convert sound wave into electricity. They are very familiar to a loudspeaker in reverse, with a diaphragm instead of a paper cone. This is a thin piece of material (paper,plastic or aluminium) that vibrates when sound waves hit it. When sound waves reach the microphone, the diaphragm vibrates at the same frequency moving the coil back and forth. This movement induces an alternating electrical current that becomes the audio signal.

Question 19

How does the ear work?

Answer 19

Sound waves are collected by the outer ear of pinna. The wave travels along the ear canal. The waves s reach the ear drum and make it vibrate. The small bones (ossicles) amplify the vibrations. The cochlea turns these into electrical signals. The auditory nerve takes the signal to the brain.

Question 20

How does the ear work 2

Answer 20

Sound waves enter the outer ear and travel along the ear canal to the eardrum. The eardrum vibrates, which makes the small bones (ossicles) in the middle ear move. This movement amplifies the eardrums vibration and causes liquid and tiny hairs in the cochlea to move. The tiny hair cells convert the movement into electrical messages. These electrical messages are sent along the auditory nerve to the brain and the sound is then heard. Sounds that are too loud can permanently damage hearing. The tiny hairs are very delicate and can be damaged over time. Once this happens they do not repair themselves and hearing becomes impaired.

Question 21

What range of frequencies can you hear?

Answer 21

Humans can only hear sound of certain frequencies. The range of frequencies a person can hear is called the hearing range. Hearing range can be tested using a pitch sweep, in which the frequency of a sound wave is gradually increased. This can be created using a signal generator and signal. The hearing range of a healthy person is 20Hz to 20,000Hz

Question 22

Hearing ranges and hearing loss

Answer 22

Everyone has slightly different hearing ranges. People lose the ability to Hera sound oh high frequency as they get older. Almost 1 in 5 people suffer from some sort of hearing loss.
Temporary hearing loss maybe caused by ear infections and colds, after which hearing recovers. Permanent hearing loss and deafness can be present at birth or occur if the ear is damaged or diseased.

Question 23

Hearing ranges

Answer 23

As we got older, our ability to hear highs pitched sound deteriorates. Some shopkeepers use this to their advantage. A device has been developed called a ‘mosquito’ which emits sounds of around 20,00Hz. This is audible, and potentially quite annoying for teenagers who may be loitering around the shop, but is not noticeable for older customers. Some human rights groups have claimed that these devices demonise young people indiscriminately. Others claim they are a cheap, non-violent way to deal with troublesome people.

Question 24

How is sound intensity measured?

Answer 24

The loudness of sounds can be measured using a sound intensity meter which is an instrument they measures in decibels. The smallest sound we can detect (almost total silence is 0dB a normal conversation is 60dB and a chainsaw is 100dB. At 80dB - 130dB you would start to feel pain and at 160dB your eardrum would puncture.

Question 25

What does deci refer to?

Answer 25

It refers to the power of 10

Question 26

What does bel refer to?

Answer 26

bel refers to Alexander Graham Bell, who invented the telephone.

Question 27

Decibels

Answer 27

Almost total silence is 10dB. A sound that is ten times more powerful is 10dB, 100 times more powerful is 20dB a 1000 times more powerful is 30dB and so on.

Question 28

Auditory range of animals

Answer 28

Many animals have a wider range of hearing than we do. Dogs can hear whistles which we can’t. Dolphins use high pitched clocks to communicate with each other. Bats find prey and navigate by using their hearing like a radar. Some animals including the hippopotamus and the elephant use low pitched sounds that travel through the ground for communication over long distances.

Question 29

Batnav

Answer 29

As well as using ultrasound to communicate, animals can also use it too find prey in the dark or simply to navigate. This is known as echolocation. Bats are nocturnal but they are able to locate prey in the dark (and distinguish between different types of prey) by emitting clicks and pulses of ultrasound. By working out how long it takes for all of the ultrasound waves to bounce off an obstacle, the bat is able to calculate the size and shape of the obstacle and where it is.

Question 30

How do marine animals use sound?

Answer 30

A water environment has very different physical properties than land environments. To communicate, mammals that live underwater have evolved specialised hearing systems. Blue whales emit low frequency rumbling sounds that travel for long distances to communicate with other whales and attract mates. Bottle nose dolphins find food with echolocation using high frequency clicks over short distances. The echo tells them the positions of fish and even their internal structure. Dolphins also use low frequency whistles for interaction.

Question 31

Animals’ hearing ranges

Answer 31

Dolphin: 70Hz - 150,000Hz
Bat: 1,000Hz - 150,000Hz
Mouse: 1,000Hz - 100,000Hz
Cat: 100Hz - 60,000Hz
Dog: 40Hz - 45,000Hz

Question 32

Amplitude

Answer 32

The height of the wave which shows how loud the sound is

Question 33

Cochlea

Answer 33

The part of the inner ear that changes vibrations into electrical signals, which are sent to the brain.

Question 34

Decibel(dB)

Answer 34

The unit for measuring the loudness of a sound

Question 35

Eardrum

Answer 35

The thin membrane in the ear that vibrates when sound reaches it

Question 36

Frequency

Answer 36

The number of waves per second, which show the pitch of the sound

Question 37

Hertz

Answer 37

The unit of frequency (Hz). 1Hz = 1 wave per second

Question 38

Oscilloscope

Answer 38

An instrument that shows a picture of sound

Question 39

Pitch

Answer 39

How high or low a sound is

Question 40

Sound

Answer 40

A form of energy produced by vibrations, which is detected by the ears.