2. WHAT IS SOUND? Sound is a form of energy.
It is made when air molecules vibrate and move in a pattern called waves, or sound waves.

3. WHAT IS SOUND?
A type of wave that is produced by a vibrating object and that travels through matter as a longitudinal wave.

4. WHAT IS SOUND? Sound is a longitudinal wave.
Sound needs a medium to travel.
Waves have amplitude (volume) frequency (pitch), wavelength (speed), etc.

5. wavelength rarefaction compression
Sound is a longitudinal wave that travels through a material medium, such as air. In this case the vibrating drum is causing the air particles to vibrate.
compression

6. WHAT IS SOUND?
For human beings, sound is one of the most important ways to communicate by:
expressing himself through speech
obtaining information through listening
obtaining stimulation (music)

7. WHAT IS SOUND?
Sound allows more complex information transfer than, for example, visual impressions.

8. WHAT IS SOUND?
The tools of information exchange through sound are:
Throat: mouth tract for producing and modulating speech sounds
Ear: for listening and analyzing sounds

9. WHAT IS SOUND?
The tools of information exchange through sound are:
Throat: mouth tract for producing and modulating speech sounds
Ear: for listening and analyzing sounds

10. HOW DO YOU MAKE SOUND?
You force air up through your voice box, or larynx
Your larynx consists of two folds of tissue called vocal chords (like guitar strings)

11. HOW DO YOU MAKE SOUND?
You force air up through your voice box, or larynx
Your larynx consists of two folds of tissue called vocal chords (like guitar strings)

12. WHAT IS SOUND?
Transmission of sound requires matter (air, liquids, solids) as transmitting medium, unlike light which can travel through matter and space.

13. WHAT IS SOUND?
Transmission of sound requires matter (air, liquids, solids) as transmitting medium, unlike light which can travel through matter and space.
Sound travels through solids and liquids
Example- knocking on a door
When you knock, the particles of the door vibrate
The vibration creates sound waves that travel through the door
When the sound waves reach the other side, the same vibrations make sounds waves in the air.

14. WHAT IS SOUND?
Sound can only travel if a medium is available to transmit the compressions and rarefactions.
wavelength
compression

15. WHAT IS SOUND?
Transmission of sound requires matter (air, liquids, solids) as transmitting medium, unlike light which can travel through matter and space.
Sound travels through solids and liquids
Example- knocking on a door
When you knock, the particles of the door vibrate
The vibration creates sound waves that travel through the door
When the sound waves reach the other side, the same vibrations make sounds waves in the air.

16. HOW SOUND TRAVELS
Sound waves carry energy through a medium without moving particles of the medium along
Each particle of the medium vibrates as the disturbance passes.
When the disturbance passes your ear you hear the sound
A common medium for sound is air, but sound can travel through many other mediums

17. The Speed of Sound All sound travels through the air at the same speed
At room temperature (20ᵒC) sound travels through the air at 343 m/s
The speed of sound is not always 343 m/s because sound waves travel at different speeds in different mediums
The speed of sound depends on the characteristics of the medium that sound travels through
1. Elasticity
2. Density
3. Temperature

18. Speed of Sound: Elasticity
Elasticity is the ability of a material to bounce back after being disrupted
The elasticity of a medium depends on how well the medium’s particles bounce back after being disrupted
In a more elastic medium the particles bounce back more quickly
In a less elastic medium the particles bounce back slower

19. Speed of Sound: Elasticity
The more elastic the medium, the faster sound travels
Sound travels well in solids because they are usually more elastic
Particles of solids do not move very far , so they bounce back and forth very quickly as the compressions and rarefaction of the sound waves pass
Most liquids are not very elastic and sound does not travel well
Sound travels very slowly in gases because gases are not very elastic

20. Speed of Sound: Density
Density is how much matter, or mass, there is in a given amount of space, or volume.
Sound travels more slowly in denser mediums
The particles of dense materials do not move as quickly as those of less dense material.

21. Speed of Sound: Temperature
Sound travels more slowly at lower temperatures than at higher temperatures
This is because at low temperatures, the particles of the medium move more slowly
At low temperatures the particles are harder to move and return to their original positions more slowly.
Example: @ 20ᵒC  343 m/s
@ 0ᵒC  330 m/s

22. Speed of Sound: Temperature
Since the temperatures are lower at higher altitudes, sound travels more slowly at higher altitudes

23. Doppler Effect: A change of pitch or wave frequency due to a moving wave source.
Weather radars use the Doppler Effect

24. Louder sound waves carry more energy
Intensity:The amount of energy that flows through a certain area in a specific amount of time
Louder sound waves carry more energy
Intensity decreases as distance increases.