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Sound
Chapter 15
What is sound?
• It is a ______________wave
• The disturbance that causes it is a
__________
• The vibrations are transferred through
_______________
• Pockets of high and low
____________make up the wave
• Frequency of sound
• The number of oscillations in _________per
second
What is sound?
• Wave length of sound
• The distance from one ______pressure
region to another
• Speed of sound
• _____________dependent
• Medium dependent
• At room temperature: ____________
How do animals detect sound?
• Air molecules hit the tympanic membrane
• The membrane vibrates causing three small
bones to vibrate
• The bones then vibrate a fluid in the cochlea
• Tiny hairs inside the cochlea are vibrated
which cause nerve cells to send electrical
signals to the brain.
Perception of sound
• Pitch
• Depends on the __________of the sound
• Young human hearing spans from
__________________________
• Frequency range ___________with age
Who hears what?
Perception of sound
• Loudness
• Depends on the ____________of the wave
• Measured in decibels (dB)
• Follows a ____________scale
The Doppler Effect
• The result of a moving sound source
• Sources approaching a detector cause _________frequencies
• Sources receding from a detector cause __________frequencies
• fd is the frequency received by the detector
• fs is the frequency produced by the source
• vd is the velocity of the detector
• vs is the velocity of the source
• v is the velocity of the speed of sound
How do instruments create
sound?
• Woodwind
• Brass
• Percussion
• String
Interference
•
•
•
•
Results from two waves ______________each other
The result of ___________combining or canceling
Appears in both transverse and longitudinal waves
Constructive interference
• When two crests or troughs __________
• __________the amplitude of the wave
• Destructive interference
• When a crest and a trough meet
• ____________or cancels the amplitude of the wave
Resonance
• The result of a sound wave frequency matching a boundary's
natural frequency
• Every object has a natural frequency
• Sound waves at this frequency interfere _____________with the
object
Standing Wave
• A standing wave is a wave that appears to stay in one place –
it does not seem to move through the medium.
• Node – a point on a standing wave that has no
_______________from the rest position.
• Antinode – a point where a crest or trough occurs
_____________between two nodes.
Resonance in Air Columns
• Open tube
• To produce a standing wave there must be a _____________on
either end of the pipe
• Each standing wave is called a ____________
• They are in multiples of __________wavelengths
• Closed tube
• To produce a standing wave there must be a _________on one
end of the pipe and an ______________on the other
• Each standing wave is called a harmonic
• They are in multiples of ___________wavelengths