Transcript Slide 1

Music by Handel
Water Music Suite - Allegro
What we already learnt …
•Graphical representation of the sound wave: Waveform
•Amplitude
Pressure
Speed
•Frequency (No. of waves per second) =
Wavelength
Amplitude
Time
Amplitude
E.g.: Frequency = 2 Hz
1s
Why do a man and a woman sound different?
Why do a violin and a piano sound different?
Why do a rooster and a monkey sound different?
What distinguishes one sound from another?
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Musical Instruments Exploration
•Try out the instruments.
•Complete Section A on your worksheet.
•Pass instrument sets onto next group.
•You’ve got 5 minutes for each sets.
Total 3 sets.
Sound Characteristic 1: Loudness
The loudness of sound is dependent on the
amount of energy which is transferred to
the medium. It in turn is dependent on the
amplitude of vibrations of the object.
Harder you hit the
membrane
(More energy transfer)
Larger amplitude
of vibration
Louder
sound
Sound Characteristic 1: Loudness
Compare the waveforms below:
Higher
amplitude!
What determines the loudness of sound?
The amplitude of vibration.
Sound Characteristic 1: Loudness
Common sounds and their estimated loudness:
Intensity
Level
# Times
Greater Than TOH
Threshold of Hearing (TOH)
0 dB
100
Rustling Leaves
10 dB
101
Whisper
20 dB
102
Normal Conversation
60 dB
106
Busy Street Traffic
70 dB
107
Vacuum Cleaner
80 dB
108
Large Orchestra
98 dB
109.8
Walkman at Maximum Level
100 dB
1010
Front Rows of Rock Concert
110 dB
1011
Threshold of Ear Pain
130 dB
1013
Military Jet Takeoff
140 dB
1014
Instant Perforation of Eardrum
160 dB
1016
Source
One convenient
unit of sound level:
Decibel (dB)
The faintest sound a
human ear can hear
is called the
Threshold of Hearing
Sound Characteristic 2: Pitch
Sound waves are caused when a vibrating
object introduce vibration into a medium.
Vibrating objects e.g. vocal cords,
guitar string & sound board, tines of
tuning fork, diaphragm of a radio speaker etc.
Medium e.g. air, water particles etc.
How often the particles of the medium vibrate
when a wave passes through the medium is
referred to the frequency of a wave.
Sound Characteristic 2: Pitch
Compare the waveforms below:
Higher
frequency!
What determines the pitch of sound?
The frequency of vibration.
Sound Characteristic 2: Pitch
Each vibrating object has its own frequency.
Piano & Guitar
Human
?
Sound Characteristic 3: Quality
Similar musical notes (i.e. same pitch) sounds
different on different instruments (e.g. piano
and guitar).
These sounds have different quality or timbre.
The quality of the pitch may be due to other
weaker frequencies (called overtones), or
deliberately mixed (as with a synthesizer).
Sound Characteristic 3: Quality
Compare the waveforms below:
What determines the quality of sound?
The waveform.
What we learnt today …
depends on the amplitude of vibration
Loudness
Loud
Soft
depends on frequency
Characteristics
of sound
Pitch
Low
High
depends on waveform
Quality or
Timbre
Clearer
Mixed
Some time for
reflection…
Have a sound day!
As one reaches puberty, the larynx
grows for both boys and girls.
Most girls’ larynx however don’t
grow as much as boys’.
Larger larynx gives a
deeper voice => lower pitch.
A) Laryngeal prominence (Adam's Apple)
B) Larynx (voice box) (vocal cords inside)
C) Trachea (wind pipe)
D) Esophagus (swallowing tube)
Our larynx (vocal box) is just like a wind instrument.
Discuss how blowing into a column of air changes pitch
when we vary:
The length of the air column
Shorter column
Shorter wavelength
Higher frequency
Longer column
Longer wavelength
Lower frequency
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