Chapter 2 - Sound Flashcards
The effects of the sound wave upon the biological tissue is called____?
❤️
Biologic effects
❤️
Sound is a type of wave that carries ____ , from place to place.
❤️
ENERGY ❤️
Sound is series of ____ and ____
❤️
Compressions and rarefactions
❤️
Areas of increased pressure and density are called ____?
Compressions
areas of decreased pressure and density are called ____?
Rarefactions
Sound must travel through a _____
Medium
Sound cannot travel through a _____
Vacuum
What type of waves is sound made of???
Mechanical and longitudinal
Sound travels in a _____ line
Straight
_____ ______ IDENTIFY which waves are sound waves
Acoustic variables
When an _____ _____ changes rhythmically in time, a _____ _____ is present.
Acoustic variable
sound wave
What are the 3 acoustic variables?
Pressure ❤️
Density
Distance
____ is this concentration of force within an area,
Force/area❤️
Pressure
Units: pascals (Pa) ❤️
____ is the concentration of mass within a volume
Density
Units: kg/cm^3
_____ measure of particle motion
Distance
Units: cm,feet & miles
What are the two types of waves?
Transverse and longitudinal
_____ ______ : particles move in a perpendicular direction to the direction of the wave
Transverse waves
_____ _____ : particles move in the same direction as the wave
Longitudinal
Regions of higher density and pressure are called ______
Compressions
Regions of lower density and pressure are called _____
Rarefactions
Acoustic _____ inform us of which waves are sound
Variables
Acoustic _____ describe the features of a particular sound wave
Parameters
Name the seven acoustic parameters
Period Frequency Amplitude Power Intensity Wavelength Speed
The time required to complete a SINGLE cycle is called a _____
Or aka as the time from start of a cycle to the start of the next cycle
Period
The typical values for a Period is _____
0.06 to 0.5 ùsecond (less than 1-millionth of a second)
A period is determined by _____
Sound source
Number of CERTAIN EVENTS that occur in a particular time
Frequency
What are the units for frequency?
Per second , 1/sec, Hertz, Hz
Hertz is Just another way of saying per second
What are the typical values for frequency???
2 MHz to 15MHz
Frequency affects ___ and _____
Penetration and axial resolution (image quality)
A wave exceeding 20,000Hz (20 kHz)
Ultrasound
____ this frequency is so HIGH that it cannot be heard by man
Ultrasound
Frequencies between 20Hz and 20,000Hz
Audible sound
Heard by man
Sound with frequencies less than 20Hz
Infrasound
This sound wave cannot be heard by man because it is so LOW
Infrasound
Less than 20Hz
_____ and ____ are related to each other, they are RECIPRICOALS
Frequency and period
The complimentary unit for sec is _____
Hz
The rate that which work is performed or the rate of energy transfer
Power
What is the unit for power?
Watts
Power _____ as sound propagates through the body
Decreases
Power is ______ to the waves amplitude squared
Proportional
If amplitude is doubled, the power is increased by a factor of _____?
Four (quadrupled)
2x2=4
The concentration of energy in a sound BEAM
Intensity
The beams power divided by the beams cross sectional area is called
Intensity
Equation for intensity
Watts/cm^2
Power(watts)/ beam area (cm^2)
Intensity ____ as sound propagates through the body
Decreases
What type of relationship does intensity and POWER have?
Direct
Proportional
When one goes up the other goes up
What type of relationship does intensity and AMPLITUDE have?
Proportional
Direct
Intensity is proportional to the amplitude of the wave ____
SQUARED
Intensity is proportional to the _____ of the wave squared
Amplitude
The effects of the medium upon the sound wave is called ____ ?
❤️
Acoustic propagation properties
❤️
If the AMPLITUDE is doubled, the intensity is increased by a factor of _____
Four
2x2=4
If amplitude is quartered, the intensity is reduced by a factor of _____
16
(1/4)^2 = 1/4 x 1/4 = 1/16
What is the definition of wavelength?
The length or distance of a single cycle.
What are the units used for wavelength?
Meters
Mm
Or any unit of LENGTH
Wavelength is the _____ or _____ of a single cycle.
Length or distance
Wavelength is determined by ______?
BOTH the source and the medium
Can wavelength be changed by the sonographer?
No
What is the equation for wavelength?
Wavelength (mm) = propagation speed (mm/ùs) / frequency (MHz)
Or
L = C/F
HIGHER frequency waves have _____ wavelengths.
Shorter
LOWER frequency waves have _____ longer wavelength.
Longer
In what type of tissue does sound have a frequency of 1MHz, with a wavelength of 1.54mm?
Soft tissue
In soft tissue, sound has a frequency of ____ has a wavelength of _____ ?
1 MHz and 1.54mm
In soft tissue you divide 1.54mm by ____ in MHz
Frequency
The rate that sound travels through a medium
Propagation speed
What’s another name for propagation speed?
Velocity or speed
Units used for propagation speed?
Meters per second
Mm/ùs
Propagation is determined by what?
Medium only - density and stiffness
All sound travels through the same speed through any specific medium.
Ex. Frequencies of 5mhz and 3mhz travel at the same speed through the same medium.
What is the average speed of all sound ( regardless of frequency) in biological or soft tissue?
1,540 m/s
- 540 km/s
- 54 mm/ùs
Lung (air) is less than _____ and ____
Fat, soft tissue and bone
Sound in a _____ medium has a short wavelength
Slow
Sound in a _____ medium has a long wavelength
Fast
The tissue type of air has a speed (m/s) of?
330 m/s
The tissue type of lung has a speed of
300-1,200 m/s
The tissue type of fat has a speed of
1,450m/s
The tissue type for soft tissue and blood has a speed of
1,540
The tissue type for tendon has a speed of
About 1,850 m/s
The tissue type of bone has a speed of
2,000-4,000 m/s
Stiffness and speed move in the ______ direction.
Same
Density and speed move in ______ directions.
Opposite
Bulk modules is the same as _____
Stiffness
Stiffness is related to change in _______
Shape “squishability”
Density is related to ______
Weight
When two waves overlap at the same location and at the same time, they combine into a single new wave.
Interference
Occurs when the amplitude of the new, combined wave is greater than the original two waves.
Constructive interference
What type of phase interferes constructively?
In-phase waves
The amplitude of the new wave is less than one of the original waves.
Destructive interference
What type of phase interfere destructively?
Out-of-phase waves
