Sound Quiz Flashcards
Quiz
What causes sound?
Sound is produced by vibrations
How does sound travel
Sound Travels in waves as the back and forth movement or “vibration” continues from the object making the sound.
Why is sound a “Pressure wave”
Because it is a wave of alternating intensities of particle pressures.
Define “Compression” and “rarefractions”
compressions are the maximum point on a sound wave
Rarefractions are the minimum points on a pressure wave.
How are wavelength frequency and amplitude related to pitch and loudness
Wavelength is just the length of the wave of sound (just like light)
Frequency is also called pitch
amplitude corresponds to a sounds loudness measured in decibles.
Formula for velocity
velocity (speed) of wave= wavelength x frequency
Does sound travel faster through solids liquids or gasses?
SOLIDS- 6,000 m/sec
liquids- 1500 m/sec
air- 340 m/sec
can sound travel in a vacuum why or why not?
No, theres no matter for compression and rarefracction- so therefore it is silent in space.
what is pitch and what causes it to vary?
pitch= frequency
every octave frequency doubles.
what is the range of human hearing?
20-20,000 Hz
define ultrasonic
sound waves above the range human hearing
Forced vs Sympathetic Vibrations
Forced vibrations: when a vibrating object comes in contact with another option and causes it to vibrate as well.
(EX: phone on table)
Sympathetic Vibrations: occur when a vibrating object comes close to another object THAT HAS THE SAME NATURAL FREQUENCY, and the second object will start vibrating.
(EX: breaking a wine glass with your voice)
Doppler effect:
EX: when a train comes at you and it sounds loud and high pitched, then when it passes it sounds lower pitched.
explanation:
as the train moves toward you it is literally bunching up sound waves in front of it, when these “bunch up” they are compressed making the frequency greater- and higher frequency means high pitch
and likewise when the train passes the waves behind it are more spread out which mean lower frequency= lower pitch
When does a sonic boom occur?
a sonic boom occurs when an airplane/rocket breaks through the sound barrier
If a sound producer is traveling at great enough speed it will catch up with the sound waves it has produces. this causes the waves to build up to a point at the front of the aircraft, this is called the sound barrier, when the aircraft goes fast enough it will break this barrier causing a shock wave or a “sonic boom”
Three types of instruments
Percussion: drums
stringed: guitar
wind: flute
how does each type of instrument generate sound?
percussion: when the instrument is hit it vibrates, causing the sound
string: when the strings vibrate, vibrations are transferred to the air and are amplified electronically
wind: blowing through a tube, as air travels down the tube it vibrates
How does each type of instrument change pitch?
percussion: changing the size shape or tension of the vibrating material
string: adjusting the tension of length of the strings
wind: covering or opening holes in the instrument tube
how are the law of reflected light and sound similar?
it is the same: the angle of incidence equals the angle of reflection. and echo is simply a sound reflection.
how far back do you have to stand to detect an echo? why?
you must stand 55 feet from the reflecting surface because….
you can only hear it 1/10 of a second after the of sound, so 345 meters, x 1/10th of a sound is 34.5 meters,
for an echo to happen if has to go halfway, reflect off of a surface and come back in that 34.5 meters.
So 34.5 m in have is 55 ft
SONAR
SOund
NAvigation
Ranging
method of echolocation used to determine the location of underwater formations or submariens- ie fishermen looking for a school of fish.
how can we reduce noise in an indoor environment?
add things to soften/break up large flat surfaces.
parts of the ear:
OUTER EAR:
pinna+ ear cannal
MIDDLE EAR:
eardrum
malleus
incus
stapes
INNER EAR
Cochlea
Auditory nerve
