1. Sound

2. Musical Instruments and other uses of Sound
Overview
The Facts of Sound
Sound Vocabulary
The Ear and Sound
Musical Instruments and other uses of Sound
Other types of waves

3. The Facts
Sound …
… is a form of energy produced & transmitted by vibrating matter
… travels in longitudinal waves
…travels faster through solids than liquids or gases

4. Sound waves and
Sound waves travel faster through solids because there are more particles close together to transfer the energy.

5. Speed of Sound Medium (Matter) Speed m/sec gas air (0o C) 331
water (25o C)
liquid sea water
iron
copper
solid glass
diamond

6. Vibration
Very fast, repeated backward and forward movement of particles of matter
For example, the vibration of the tuning fork creates pure sound.
The hammer hits the nail and the particles vibrate making noise.

7. Waves transport energy without moving matter
Watch the 3 red dots
You will see them vibrate, but not move with the wave to the end.
All the particles are vibrating but stay fixed

8. Sound Waves
Alternating areas of high and low pressure in the air (compressions and rarefactions)

9. Sound Waves
ALL sound is carried through matter as sound waves. In a vacuum there are no particles so sound cannot travel.
Alternating areas of high and low pressure in the air (compressions and rarefactions)

10. Sound Waves
Because sound waves need particles to be transmitted they are mechanical waves
ALL sound is carried through matter as sound waves. In a vacuum there are no particles so sound cannot travel.
Alternating areas of high and low pressure in the air (compressions and rarefactions)

11. Sound Waves
Sound waves move out in ALL directions from a vibrating object.
Because sound waves need particles to be transmitted they are mechanical waves
ALL sound is carried through matter as sound waves. In a vacuum there are no particles so sound cannot travel.
Alternating areas of high and low pressure in the air (compressions and rarefactions)

12. Compression
Where particles are pressed together as the sound wave moves through matter.

13. Compression
Where particles are pressed together as the sound waves move through matter
For example,
a wave travels through the springs just like sound waves travel through the air
the places where the springs are close together are like compressions in the air.
compression

14. Compression Wave = Longitudinal Wave
Compressions - The close together part of the wave.
Rarefactions - The spread-out parts of a wave.
Compression Wave = Longitudinal Wave

15. Each wave particle vibrates back and forth in the same direction of
Longitudinal Wave (Compression Wave)
Each wave particle vibrates back
and forth in the same direction of
the wave.

16. Sound waves covered till now:
States of matter (solid, liquid, gas)
Speed of sound through matter
No sound in a vacuum
Vibration
Compression + Rarefaction
Longitudinal waves
Remember that ….

17. Waves transfer energy without moving matter.
If you watch the 3 red dots you will see them vibrate, but not move with the wave to the end.
Frequency= waves/time

18. Wavelength & Frequency
Wavelength is the distance between one part of a wave and the same part of the next wave
Frequency is the number of waves passing a point in a certain tme
Many waves = high frequency
Few waves = low frequency

19. Pitch = Frequency How high or low a sound is
Pitch depends on the frequency of a sound wave
For example,
Low pitch
Low frequency
Longer wavelength
High pitch
High frequency
Shorter wavelength

20. Frequency is measured in Hertz
For example:
If 20 waves are made per second, then the frequency is 20 cycles per second =
20 Hertz Hz

21. 20 Hz – 20,000 Hz The human ear can only hear sounds between
20Hz and 20,000 Hz (Frequency/Pitch)
20 Hz – 20,000 Hz
Below 20 Hz is called infrasound
Above 20,000 Hz is called ultrasound

22. Ultrasound Infrasound Sounds in the range from 20,000-100,000Hz
sound waves with frequencies above the normal human range of hearing.
Sounds in the range from 20, ,000Hz
Infrasound
sounds waves with frequencies below the normal human range of hearing.
Sounds in the Hz range

23. The Ear Sounds reach our ears through vibrating air particles
Our ears capture sound waves and turn them into signals that go to our brains
Sound waves move through 3 parts of the ear; outer ear, middle ear, + inner ear

24. The Human Ear

25. Amplitude
is the maximum distance
the particles in a wave
vibrate from their rest positions.

26. Amplitude = loudness
The intensity of a sound decreases as you move away from a sound. The sound is softer.
As the source of a sound comes closer the sound becomes louder, more intense
soft
loud
A loud sound has a high amplitude
A soft sound has low amplitude

27. The volume or loudness of sound is measured in decibels
Amplitude = loudness
The volume or loudness of sound is measured in decibels dB

28. Loudness of Sound in Decibels
Loudness (dbs)
Hearing Damage
Average Home
40-50
Loud Music
90-100
After long exposure
Rock Concert
Progressive
Jet Engine
Pain

29. Sound and Instruments
Different musical instruments create different sound vibrations
Wind instruments by blowing and vibrating the air e.g. flute, saxophone, organ
String instruments by touching and vibrating the strings e.g. guitar, violin, piano
Percussion instruments by hitting a surface e.g. drums, cymbals, triangle

30. Sound and Instruments
Instruments can be played at different pitches (musical notes) by changing the lengths of different parts.
For example,
Another way to make different pitches is to change the thickness of the material that vibrates.
A trombone’s mute absorbs some of the sound waves produced, so a different sound is made.

31. Humans use sonar to locate or find objects
Sonar uses reflected sound waves (echoes) to find objects in water or air
Humans use sonar to locate or find objects
Animals use sonar or echo location to find their prey (food); these sounds have such a high pitch or frequency that the human ear cannot hear them

32. Ultrasound (above 20,000 Hz)
Ultrasound waves are used in medicine They are also reflected sound waves

33. Other waves are transverse, electromagnetic and water waves
Other types of waves
Remember sound waves are longitudinal and mechanical
Other waves are transverse, electromagnetic and water waves

34. Transverse waves
wave particles vibrate
in an up-and-down motion.

35. Transverse waves Crests - Highest part of a wave
Troughs - The low points of the wave

36. Electromagnetic waves
Electromagnetic waves travel as transverse waves
Electromagnetic waves CAN travel through a vacuum
Light, microwaves, x-rays, and TV and radio transmissions are all examples of electromagnetic waves

37. Water Waves
The blue surface particles move in a clock-wise direction

38. Wave concepts covered in this power point:
Sound Waves
Other waves
States of matter (solid, liquid, gas)
Speed of sound through matter
No sound in a vacuum
Vibration
Compression + Rarefaction
Longitudinal waves
Wavelength
Frequency = Pitch
Hertz Hz
20 – 20,000 Hz
Ear (outer, middle, inner ear)
Amplitude = Loudness = Volume
Decibels dB
Sonar
Ultrasound, infrasound
Transverse waves
Crests
Troughs
Electromagnetic waves
Water waves

39. That’s all folks!