Ch.2 Sound Flashcards
what do waves transfer from one location to another?
carry energy from place to place
What kind of wave is sound?
A mechanical wave
Travels in a straight line
A longitudinal wave
cannot travel thru a vacuum only a medium (solid, gas, liquid)
Describe the how molecules travel in a sound wave
molecules are alternately compressed and rarefied as they travel thru a medium
What are acoustic variables?
oscillations in:
pressure
density
distance
identifies a sound wave
(vary with location and time)
What are acoustic parameters?
They are used to describe the characteristics of a sound wave.
What are the seven acoustic parameters?
Period
Frequency
Amplitude
Power
Intensity
Wavelength
Propagation speed
Transverse wave
particles move in a direction that is perpendicular to the direction that the wave propagates
(string moving up & down)
Longitudinal wave
particles move in the same direction that the wave propagates
(Slinky)
Pressure
concentration of force in an area
units: Pascals (Pa)
Many molecules compressed together in an area means that the pressure is?
Increased
(peak)
Density
concentration of mass in a volume
units: kg/cm^3
Distance
measure of particle motion
units: cm, mm, um
How are sound waves displayed?
In phase or out of phase
In phase
when peaks of all waves occur at the same time and same location
“in step”
Out of phase
when the peaks occur at different times and at different locations
(trough to peak)
Interference
when two or more sound beams travel through a medium and arrive at a point at the exact same time
(combine into a single wave)
Constructive Interference
when several in phase waves come together to form a single wave with a greater amplitude than either original waves
Destructive Interference
when a pair of out of phase waves come together and cancel out each other amplitude. Result is a single wave of lesser amplitude than either originals
Which types of waves will exhibit both constructive and deconstructive interference?
Waves of different frequencies
