Sound

Página 1

There are many many sounds, but they all have one thing in common

Sounds only happen when something vibrates

When something vibrates to make a sound, it moves backwards and forwards.

We can sometimes demonstrate a vibration even if we see one

Página 2

How sound can reach our ears

When the cone of a loudspeaker is vibrating, it makes the air next to it vibrate it as well.

The air is squashed and stretched to make sound waves.

These sound waves travel through the air until they reach our ears.

When the vibration reach our eye, they make our eardrums vibrate.

These tiny piece of skin pass on their vibration through a series of bones to a structure called the cochlea.

These message are sent into the brain, and finally we hear a sound.

Página 3

Página 4

Sound travels as waves:

Sound energy travels because it's passed from molecule to molecule in the air, between the source of sound and our ears.

The molecule move backwards and forwards in a pattern we call sound wave. The pattern looks as if some molecules are pushed together: these parts of the wave are called comperhession; other are more spread out

Página 5

Sound travels as waves:

Sound energy travels because it is passed on from molecule to molecule in the air, between the source of the sound and our ears.

The molecules move backwards and forwards in a pattern we call a sound wave

The pattern looks as if some molecules are pushed together

These parts are called compressions; other are more spread out

Página 6

Sound and echos:

Sound waves can be refelected in the same way as light rays

Sound travels much more slower than light, so it takens some time to hear over the air

If u make a sound such as a shout or a bang near cliff or big building, u may hear a echo.

This is caused by the sound waves going back at u.

Sound waves and echoes can be used to locate underwater objects.

A ship on a surface sends out sound waves and then picks up the echo from anywhere beneath the ship.

This is used to locate sunken ships, to detect submarines, to search for shoals of fish and to check that the water is deep enough for a ship to move safely to shallow water

Página 7

Sound needs a material to travel through:

Sound waves most have a meterial to past through, and can travel through Gases, Liquids, and Solids.

Air is an example.

An example of a solid includes brick, wood and glass.

Página 8

con.t Sound waves travel more effectinitly through solids and liquids than gases

Anything sound energy can travel on is a medium

Sound can't travel in a vaccum

A vaccum is a space where there is no air, no water, or other molecules to be compressed and rarified. Light can travel through a vacuum because light rays don't need particles to pass on their energy

Promblems with hearing:

Driffrent people can hear drifferent sounds

The audible range for a person tells us the upper and lower frequencys of that sound

The audible range for a person depends on how well the vibrations in the eardums are passed on through the tiny bones

As we get older, these bomes wear out and we find it esspically dificult to hear high-frequency sounds

The audiable range gets reduced as we get older!

The ears can suffer more serrious damage and we become death. This deafness can be tempoary or permant, depending on what caused it

Here are some of the promblems:

Página 9

The speed of sound:

Sound travels much slower than light.

This makes it much easier to measure the speed of sound than the speed of light.

These measurements can be made outdoors using echo timing, or indoors using an electronic timer.

Página 10

Because light travels so much more quickly than sound, we can see an event happen before we hear it.

A well-known example of this difference concerns thunder and lightening.

During a thunderstorm you usually see the lighting before u hear the thunder

In fact, light travels so quickly u see it as soon as happens

The differences between the speed of sound and light means you can work out how far the thunderstorm is away from u.

Equation for distance away=time between lighting and thunder/3

Página 11

Different sounds:

A microphone is able to change the vibration in the air into electrical signals.

These signals can be seen if the microphone is connected.

This wave length is a trace

The trace shows the changes in pressure of the air as it hits the microphones

Página 12

All sounds are caused by vibration.

Sometimes these vibration are to small to see, but sometimes u can see quite easily.

If u start to play a guitar, u would see the string vibrate as it makes a sound.

You could make the sound louder if the vibrations were very hard.

The sound would be quiter if the strings were plucked gently and the vibrations would be quite small

Large vibration makes bigger sound waves.

A big sound wave has more energy than a smaller one.

A quiet noise mean there are small vibrations, a small amlitude, and little bit of energy.

A loud noise creates big vibrations, big amplitude, and a lot of energy

The size of the amplitude is called the amplitude of the wave.

Pitch-Another difference between sounds:

A pitch is how high or low the sound is.

Seveal things that effect the pitch:

The size of the object that is vabriting: long and think gives a low-pitched sound; and short and thin gives a high-pitched note

The tightness of the object that is vibrating: a tight string vibrates and makes a high note; and a loose string vibrates and make a low note.

The pitch of the sound depends on how many vibration are fitted into the same amount of time.

Hertz(Hz.) is the measurement