Sound is a form of energy created by vibrations that travel through matter as longitudinal waves. When an object vibrates, it causes the air particles around it to move in a compression and rarefaction pattern that transfers the sound energy. Sound travels through gases, liquids, and solids as a medium and cannot travel through a vacuum. The pitch and loudness of sound depends on the frequency and amplitude of its waves. Musical instruments create sound through vibration of strings, woodwinds, or percussion. The human ear detects sound waves through vibration of the ear drum and small bones, which are translated into nerve signals in the cochlea and perceived as sound by the brain.

1. Sound Energy
Made by Dr. Soha Bedair

2. What is sound?
 Sound is
– A form of energy made by vibrations.
– When an object vibrates it causes the air particles
around it to move.
– These particles bump into particles close to them
and this continues until they run out of energy.

3. Sound creates :
 Compressions & rarefactions:

4. Try this:
 Put your finger on your neck and say “aah”
as loud as you can.
 Now say it as soft as you can.
 You can not only hear the sound, but you can
feel the vibration inside your throat.

5. How does sound travel?
 Sound travels through all forms of matter—
gases, liquids and solid.
 These are called the medium.
 Sound cannot travel through a vacuum.

6. Volume:
 It is measured using sound level meter
 The unit for measuring the volume is
decibels(dB)

7. How does sound travel?
 Sound passes through the medium as
longitudinal waves.
 While light travels by transverse waves

8. How do musical instruments create
sound?
 It depends on the type of instrument. There
are four types.
– Woodwind
– String
– Percussion

9. Woodwinds Instruments
 Woodwinds make music by blowing on the
top of the instrument or on a reed.
Flute
Oboe
Clarinet
Bassoon
Piccolo

10. Percussion Instruments
 Percussion instruments make music by
striking, shaking or scraping them.
Drum
Cymbals
Tambourine
Xylophone
Piano
Maracas

11. String Instruments
 Strings make music by plucking or
strumming the strings.
Violin
Cello
Electric
Guitar
Guitar Harp

12. Pitch, frequency and amplitude:
 Pitch: it determines how high or low the
sound is.
is produced by short objects. is produced by long obj.
tight( stretched)objects. Loose obj.

13. Frequency:
 It is number of vibrations in one second.
 As the number of vibrations increases the
frequency and pitch increases.

14. Louder
Softer
How else can we change sound?
 We can make it louder or softer by changing
the amplitude of the height of the wave.
 The higher the amplitude, the louder the
sound. The lower the amplitude the softer
the sound.

15. Echo & how the sound energy is
absorbed:
 Echo: is when the sound bounces back from
a hard surface.
 If sound hits soft surface is absorbed
more>>>> than hard surfaces.

16. How is sound transmitted?
 The sound waves have energy.
 The sound waves needs a matter to be
transmitted.(solid, liquid or gas).
 We call the matter (medium).

17. Sound transmission through
different media:

18. Parts of the ear:
cochlea

19. How we hear a sound?
 When the sound wave reaches our ear drum, it hits it
and our ear drum starts to vibrate.
 Then the three bones attached to the ear drum starts
to vibrate.
 The cochlea then translates these vibrations into
signals.
 The brain receives those signals by nerves.
 Then the brain translates these signals into sound.