Chapter 2 Sound Waves Flashcards
Sound Waves
-sound pulses travel through biologic tissue or a “media”
-sound is reflected from boundaries between structures
-sound is returned to the transducer and processed into images
Forms of waves:
-heat
-sound
-magnetic
-light
Sound waves carry energy
all waves carry energy from one location to another
What kind of wave is sound?
a mechanical wave
Sound waves
-not capable of transmitting energy through a vacuum
-requires a medium to transport energy
Rarefactions
regions of low pressure and density
compressions
regions of high pressure and density
waves
repeating series of compressions and rarefactions
Sound Waves pt 2
-sound travels in a straight line
-molecules in the medium vibrate back and forth from a fixed position
-molecules are squeezed together and stretched apart
Sound Waves Acoustic Propagation properties
how the medium affects the sound
Sound Waves Biologic Effect
how the sound wave effects the biologic tissue (media) through which it passes
Acoustic Variables
-quantities that change in a sound wave
-an acoustic variable with a rhythmic oscillation is a sound wave
What defines sound waves?
oscillations within acoustic variables
What are the three acoustic variables distinguishing sound waves?
-pressure
-density
-distance
What’s another name for sound waves?
acoustic waves
Acoustic Parameters
-describe the sound wave features
-there are 7 acoustic parameters
Types of soundwaves: transverse
-particles move perpendicular to propagation
Ex: holding the end of a string and shaking it up and down
-energy moves away from your hand
Types of sound waves: longitudinal
-particles move parallel to propagation
Ex: pulling a slinky
-sound is a longitudinal wave
IN-PHASE waves
peaks and troughs occur at the same times/locations
“In Step”
Out-of-Phase waves
-peaks and troughs occur at different times/locations
“Out of step”
Interference
> 1 sound beam may travel in a medium
-multiple beams may arrive at identical locations at the same time
-waves lose their individual characteristics
-waves combine to form a single wave
-happens to in-phase and out-of-phase waves
Constructive interference
-the interference of in-phase waves
-forms a single wave of greater amplitude
Destructive interference
-interference of out-of-phase waves
-forms a single wave of lesser amplitude
-complete destructive interference may occur
Interference of waves with different frequencies
both constructive and destructive interference occur
