Transcript Slide 1

Pitch, Loudness, and
Quality of Sound
by
Rifki Irawan
Frequency and Pitch
Pitch = frequency of sound
The perceived pitch of a sound is just the ear's response to
frequency.
A high pitch sound corresponds to a high frequency sound wave
and a low pitch sound corresponds to a low frequency sound wave.
A high pitch (>2kHz) will be perceived to be getting higher if its
loudness is increased, whereas a low pitch (<2kHz) will be
perceived to be going lower with increased loudness.
The ear has an ability to detect such frequencies and associate
them with the pitch of the sound, because sound waves traveling
through air are longitudinal waves which produce high- and lowpressure disturbances of the particles of the air at a given
frequency.
pressure
Low frequency wave
time
period
The pitch of a note increases with the frequency of vibrations
pressure
High frequency wave
time
period
Intensity and Loudness
The intensity of a sound wave depends on the amount of energy in
each wave.
Intensity of a sound wave increases as its amplitude increases.
Loudness is the human perception of sound intensity.
The higher the intensity and amplitude, the louder the sound .
The loudness of a sound increases with the amplitude of vibration .
The intensity of a sound is measured in units called decibels (dB) .
The faintest sound that can be heard by most human ear is 0 dB.
Sound with intensities above 120 dB may cause pain and hearing
loss .
Familiar sounds and their intensity
Level (dB)
Effect
Pin dropping
0
Limit of hearing
Soft whisper
30
Soothing
Hair dryer
50
Normal conversation possible
School dining hall
60
Disturbing
Noise
Note
loud if not involve
Motorcycles
andthat
cars the prolonged
80 listening to
Annoying
music through headphones/earphones can
90of common
Signs of ear damage;
ringing in ears
The noise
levels
sounds
damage your ears as well
Pneumatic drill
Shouting in ear
100
Working efficiency falls
Heavy hammering machine
110
Conversation impossible
Police car sirine
120
Ear uncomfortable
Music concert
130
Ear pain
Nearby jet at take off
140
Unbearable
> 150
Ear damage
Intensity Calculation
The amount of energy which is transported through a given area of
the medium per unit of time is known as the intensity of the sound
wave.
Intensity =
Energy
Time x Area
=
Power
Area
Typical units for expressing the intensity of a sound wave are
Watts x meter -2 ( W ∙ m -2 ).
String instruments :
The pitch of the notes produced by stringed instruments depends
on :
1. the tension
2. the length; and
3. the mass per unit length (or thickness)
To obtain a note of higher pitch, the frequency of the string can be
increased in the following ways :
1. increasing the tension
2. shortening the length; and
3. using the thinner string of smaller mass per unit length
Humans are equipped with very sensitive ears capable of detecting
sound waves of extremely low intensity = 0 dB
0 dB = 1 x 1012 W ∙ m-2
0 dB = a sound which will displace particles of air by one-billionth
of a centimeter
have a nice day !
This faintest sound which a human ear can detect is known as the
threshold of hearing ( TOH )
To be continued . . . !
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