Transcript Parts of sound waves

Vibrations
Sound waves are compression
waves. They are made of atoms
being pushed, or compressed,
by other atoms.
carry in
Why wouldn’t sound waves
space?
Sound waves are mechanical waves,
which means they need a medium to
travel through and they can’t travel
through a vacuum.
Vibrations
Parts of sound waves …
Wavelength – distance between
troughs on either side of a
single wave.
Vibrations
Parts of sound waves …
Amplitude – height of the sound
wave.
high wave = loud
low wave = soft
Vibrations
Parts of sound waves …
Frequency – speed,
the number of vibrations per second.
frequency = pitch
fast vibrations = high pitch
slower vibrations = low pitch
Vibrations
States of Matter
Sound waves travel …
Slowly through gases,
more quickly through liquids,
and fastest through solids
Vibrations
Vibrations
Speed of Sound: 343 m/sec
(Speed of Light: 300,000 km/sec)
Which is faster?
Sound
Question: Can you experience sound
waves by feeling vibrations?
– When the bass is turned up high.
Sound
Loudness is the human perception
of how much energy a sound wave
carries.
Sound
• Pitch: how high or low a sound is.
Pitch corresponds to frequency. The
higher the pitch the higher the frequency.
• Question: Name a musical instrument with
a high pitch.
• Question: Name a musical instrument with
a low pitch.
Sound
Decibel Scale: measure of the
energy carried by sound
waves.
Sound
• Pitch: Humans can detect frequencies
between about 20Hz and 20,000Hz.
• Dogs can detect up to 50,000Hz.
• Bats as high as 150,000Hz.
Sound
• Dangerous levels of sound energy.
• You must learn to protect your hearing or you
may have hearing problems later in life.
• Have you ever had ringing in your ears?
Sound
• Echo: a reflected sound wave
Sound
• What is SONAR?
• Sound Navigation And Ranging.
Uses sound to detect objects under
the surface of the water.
Videos: Submarines and Sonar 2, Dolphins Sonar 1:30
Sound
• Echolocation: emitting high
pitched squeaks and listening for
echoes to determine location.
• Bats and dolphins use echolocation to
navigate.
•
Video: Echoes and
Echolocation 1:29
Sound
• Doppler Effect: The change in
frequency that occurs when a source of
sound is moving relative to the listener.
• Example the pitch of a siren gets higher as it
moves toward you. As the siren moves
away, the pitch gets lower.
• Radar guns use the
Doppler effect.
Video: Doppler Effect 1:28
•
Sound
Sound waves can be used to treat certain
medical problems.
1.
2.
Small incision is made in the eye, then an ultrasonic instrument
uses sound waves to break up the lens, and the particles are
removed.
Breaking up kidney stones.
Video: Ultrasound 2:44
Music
• Natural frequencies: every object will
vibrate at a certain frequency.
Music
• Music: a group of sounds
deliberately produced to make a
regular pattern.
• The difference between music and noise can vary from
person to person.
• Music is created by vibrations.
– You beat a drum, the head vibrates. You play
a guitar the string vibrates. You tap a bell, it
vibrates at a certain frequency.
Music
• Most musical instruments produce
more than one frequency at which
they vibrate.
• Fundamental frequency: the
lowest frequency produced by a
vibrating object.
• Overtones: higher frequencies
produced by a vibrating object.
Music
• Resonance: an object is made to
vibrate at its natural frequency by
absorbing energy from a sound wave.
– The vibrating tuning fork causes the table to
vibrate at the same frequency, or resonate.
The combined vibrations of the table and
tuning fork increase the
loudness of the sound
waves produced.
Music
• Reverberation: repeated echoes
of sound.
– In a empty gym the sound of your voice can
be reflected back and forth several times by
the floor, walls, and ceiling.
– Video: Reverberation 2:15
Ear
•
Definitions:
anvil - (also called the incus) a tiny bone that passes vibrations from the hammer to
the stirrup.
cochlea - a spiral-shaped, fluid-filled inner ear structure; it is lined with cilia (tiny
hairs) that move when vibrated and cause a nerve impulse to form.
eardrum - (also called the tympanic membrane) a thin membrane that vibrates when
sound waves reach it.
Eustachian tube - a tube that connects the middle ear to the back of the nose; it
equalizes the pressure between the middle ear and the air outside. When you "pop"
your ears as you change altitude (going up a mountain or in an airplane), you are
equalizing the air pressure in your middle ear.
hammer - (also called the malleus) a tiny bone that passes vibrations from the
eardrum to the anvil.
nerves - these carry electro-chemical signals from the inner ear (the cochlea) to the
brain.
outer ear canal - the tube through which sound travels to the eardrum.
pinna - (also called the auricle) the visible part of the outer ear. It collects sound and
directs it into the outer ear canal
semicircular canals - three loops of fluid-filled tubes that are attached to the
cochlea in the inner ear. They help us maintain our sense of balance.
stirrup - (also called the stapes) a tiny, U-shaped bone that passes vibrations from
the stirrup to the cochlea. This is the smallest bone in the human body (it is 0.25 to
0.33 cm long).
Ear
Outer Ear: Collects sound waves
and directs them into the ear canal.
(also called the pinna)
Ear
Middle Ear: Sound waves vibrate the eardrum,
which is a membrane that stretches across
the ear canal. When the eardrum vibrates, it
transmits vibrations to three small bones (hammer,
anvil, stirrup) which amplify the sound
Ear
Inner Ear:
• One of the three small bones vibrates
another membrane leading into the inner
ear, which is filled with fluid.
• Vibrations in the fluid are transmitted to
hair-tipped cells.
• These cells generate signals containing
information about sounds.
• The nerve impulses from the cells then
travel to the brain.
•
Video: Ear 1