Physics - Sound Flashcards
HOW IS SOUND MADE?
Vibrations or oscillations
SOURCES OF VIBRATION:
-Vocal chords,
-strings on an instrument,
-lips when one plays the trumpet,
-reed on an oboe,
Cone in loudspeakers.
WHICH PART OF THE EAR VIBRATES?
The eardrum
HOW DOES SOUND TRAVEL FROM THE SOURCE TO OUR EARS?
-Vibration of source - eardrum vibrates,
-Above causes inner ear hairs to vibrate,
-Above causes generation of electrical signals,
+Electrical signals travel to nerves in brain - hearing.
Also, forces of vibrating air next to ear drum causes vibration
LONGITUDINAL WAVE
Vibrations parallel to the flow of the sound energy. E.g. direction of sound from speaker, same as direction of air particle vibration from candle flame. see physics - sound inn photos
THE EFFECT OF SOUND TRAVELING THROUGH AIR ON PARTICLES AND AIR PRESSURE:
PARTICLES: see photos physics - sound
0 Sound sent to ear - pushes and pulls air particles next to it, meaning air particle vibrate left and right,
0 Sound creates compressions (Air PARTICLES bunched together) and rarefactions (Air PARTICLES +spaced out),
0 Sound wave/ sound = longitudinal sound wave - air particles travel in same direction as sound waves.
AIR PRESSURE:
1 Sound creates compressions (Air PRESSURE ^ than normal) and rareFACTIONS (Air PRESSURE lower than normal)
COMPRESSION
+Air particles bunched together,
+Region where air pressure is ^ than normal.
RAREFACTION
_Air particles more spaced out,
_Air pressure lower than normal.
SOUND TRAVELS AS A LONGITUDINAL WAVE
see photos physics- sound
RECALL Qs AND As FROM THE BELL JAR EXPERIMENT:
see photos - physics- sound
WHICH DOES SOUND TRAVEL FASTEST IN, SOLIDS, LIQUIDS OR GASES?
Hint:
hard wood - 4000 m/s
Aluminium - 5100 m/s
Iron and steel - 5000 m/s
Seawater - 1560 m/s
Water - 1440 m/s
H - 1300 m/s
He - 1005 m/s
Air - 331 m/s
Answer = solids, not how clearly you can hear it; but how fast.
THE DENSER THE MEDIUM, THE SLOWER SOUND TRAVELS; TRUE OR FALSE?
False, the more dense the medium the faster sound travels, should have done true because I am reading this question a lot so will skim past it without real acknowledgement meaning I will believe above it true, this is just to keep you on your toes though.
sound travels slowest in gases; true or false
True
SOUND OF A SOLID IN A VACCUM IS…
…quieter than the sound of a solid not in a vaccum
Sound waves cannot pass through a vaccum
VACCUM
A region of space with no particles or atoms in it, e.g. space.
CALCULATION OF THE SPEED OF SOUND, TELL US:
see photos physics- sound
‘Mach 1’ = ?
Jet plane flies faster than the speed of sound (reasoning = sound waves cannot escape the nose of the jet). Normally leads to ‘sonic boom’.
WHAT HAPPENS WHEN MACH 1 IS EXCEEDED?
‘sonic boom’ x2 occurs, very loud sounds. To fly above Mach 1 need to be over ocean - noise pollution.
HOW TO CREATE AN ‘audible’ ECHO:
1) Need reflection of sound to come from a surface, hardsurface.
Smooth because:ensures all sound reflects back to observer along same line (sound scatters in all directions, observer hears multiple echoes without this).
Hard because:ensures most of the sound reflected not absorbed.
see physics- sound in photos, observe well use brain
HOW DO YOU MEASURE THE SPEED OF SOUND USING ECHOES?
see photos in physics - sound
USES OF ECHOES?!?!
1) echolocation e.g. dolphins, bat, humans.
2) sonar, e.g. image of sea floor.
3) length of a steel/aluminium/iron rod e.g. measure time it takes for each to reach back tot he start of the rod.
4) flaw detector, e.g. measure distance it takes to see how deep flaw is and compare to length of steel rod for accuracy and to see if there is a flaw in the first place.
USEFUL SPEED EQUATION FORO ECHOES:
d = s t/2
DIVIDED BY TWO BECAUSE ECHOES ARE A MIMIC OF THE REAL SOUND SO THERE ARE 2 SOUNDS IN TOTAL.
see photos in physics - sound
REVERBERATION:
When the echo time is <0.1s, brain can’t tell echo apart from first sound. Observer hears 1 smoothed-out sound.
Heard in a room with no absorbents e.g. sound-absorbing furniture.
CAUSES OF REVERBERATION?
- Multiple echoes
see photos in physics - sound
FREQUENCY.
NUMBER OF VIBRATIONS PER SECOND
see photos in physics - sound
AMPLITUDE
HOW FAR THE VIBRATION MOVES FROM ITS REST POSITION, e.g. how far the cone on a loudspeaker moves from its resting position.
see photos in physics - sound
RANGE OF HUMAN HEARING
Normal Hearing:
- hear up to 25dB to hear average garden birds at 6000Hz (roughly)
Mild Hearing Loss:
-hear up to 26-40dB to hear an average person speaking at 1000 Hz
Severe Hearing Loss:
- hear up to 61-80dB to hear a piano at 1000 Hz
Profound Hearing Loss:
-81+dB to hear a motorbike at 4000 pitch (Hz)
Average human cannot hear above 20,000Hz or below 20Hz
HOW DO YOU MINIMISE NOISE-INDUCED HEARING LOSS?
-Limit exposure to loud sounds.
Amount of time one should be exposed to varies to the amount of sound (dB) they are exposed to.
see photos in physics - sound
INTERPRET AND DRAW CRO WAVEFORMS:
see photos in physics - sound
HOW NOISE-INDUCED HEARING LOSS AFFECTS ABILITY TO HEAR SOUNDS:
The worse hearing one has; the more dB (louder) they need to hear sounds.
see photos in physics - sound
HOW FREQUENCY IS RELATED TO PITCH
Frequency of a vibration ^ = pitch of note ^
Frequency of a vibration ^ = number of waves seen on the CRO increases.
X-axis is always time.
see photos in physics - sound
EFFECT OF AMPLITUDE ON LOUDNESS
Large amplitude waves = holds a lot of energy.
Large amplitude wave = sound wave is loud
A WAVE OF ZERO AMPLITUDE CARRIES NO ENERGY; A SOUND WAVE OF ZERO AMPLITUDE IS COMPLETELY QUIET- THERE IS NO WAVE the wave would not knock over a sandcastle ;) :0
see photos in physics - sound
Break 🧋🚱🥛🥤🥤
If need more breaks click do not know, if less click completely know.
