1|Page
Sonography Principles & Instrumentation
Examination (ARDMS SPI) | 2026
Directly Related or Proportional - ANSWER -2 or more items associated
AND connected; (1 item ↑, the other ↑)
Intensity - ANSWER -Intensity is proportional to Power. Intensity AND
Power are proportional to Amplitude2
Inversely Related - ANSWER -2 or more items associated AND
connected; (1 item ↑, the other ↓)
Period & Frequency - ANSWER -Period & Frequency are inversely
related. Period ↑ Frequency ↓
Reciprocal - ANSWER -2 numbers multiplied (ｘ) the result (=) is one (↿)
*Reciprocals are also inversely related; 1 item ↑, the other ↓*
Sound Waves - ANSWER -All waves carry energy from one location to
another. Sound is a mechanical wave
pg. 1
,2|Page
Medium for Sound - ANSWER -Sound cannot travel through vacuum;
MUST travel through a medium
Sound Wave Direction - ANSWER -Sound travels in a straight line
Longitudinal Waves - ANSWER -Sound waves are longitudinal
Acoustic Waves - ANSWER -Sound waves are also referred to as
acoustic waves
Acoustic Variables - ANSWER -[ Pressure, Density, & Distance ] Used to
distinguish between sound waves and other types of waves
Pressure - ANSWER -Concentration of force in an area measured in
Pascals (Pa)
Density - ANSWER -Concentration of mass in a volume measured in
kg/cm3
Distance (particle motion) - ANSWER -Measure of particle motion
measured in cm, ft, mile
Acoustic Parameters - ANSWER -There are seven acoustic parameters
pg. 2
,3|Page
Period - ANSWER -Time from the start of one cycle, to the start of the
next cycle measured in microseconds (μs)
Frequency - ANSWER -Number of cycles that occurs in 1 second
measured in Hertz (Hz) 'per second'
Amplitude - ANSWER -Difference between the minimum value & the
average value of the acoustic variable
Power - ANSWER -Rate of energy transfer measured in Watts (W)
Wavelength - ANSWER -Distance or length of one complete cycle
measured in mm, meters, any unit of length
Propagation Speed - ANSWER -Rate at which a sound wave travels
through a medium measured in m/s, mm/μs
Wavelength Formula - ANSWER -wavelength = 1.54 mm/μs
Sound Speed Order - ANSWER -Sound travels fastest in solids, slower in
liquids, & slowest in gases. Order from fastest →slowest: Bone
→Tendon →Muscle →Blood →Liver
Stiffness - ANSWER -Ability of an object to resist compression
pg. 3
, 4|Page
Density & Speed Relationship - ANSWER -Density & speed are inversely
related
Bulk Modulus - ANSWER -Bulk Modulus is the same as stiffness
Speed Determinants - ANSWER -Speed is determined by the density &
stiffness of the medium
Speed Increase with Stiffness - ANSWER -If stiffness increases ↑, speed
increases ↑
Speed Decrease with Density - ANSWER -If density increases ↑, speed
decreases ↓
Speed Formula - ANSWER -Speed = Frequency (Hz) x Wavelength (m)
Pulsed Waves - ANSWER -Pulsed ultrasound has 2 components:
Transmit, talking, or 'on' time and Receive, listening, or 'off' time
Pulsed Duration - ANSWER -Actual time from the start of a pulse, to the
end of a pulse
pg. 4
Sonography Principles & Instrumentation
Examination (ARDMS SPI) | 2026
Directly Related or Proportional - ANSWER -2 or more items associated
AND connected; (1 item ↑, the other ↑)
Intensity - ANSWER -Intensity is proportional to Power. Intensity AND
Power are proportional to Amplitude2
Inversely Related - ANSWER -2 or more items associated AND
connected; (1 item ↑, the other ↓)
Period & Frequency - ANSWER -Period & Frequency are inversely
related. Period ↑ Frequency ↓
Reciprocal - ANSWER -2 numbers multiplied (ｘ) the result (=) is one (↿)
*Reciprocals are also inversely related; 1 item ↑, the other ↓*
Sound Waves - ANSWER -All waves carry energy from one location to
another. Sound is a mechanical wave
pg. 1
,2|Page
Medium for Sound - ANSWER -Sound cannot travel through vacuum;
MUST travel through a medium
Sound Wave Direction - ANSWER -Sound travels in a straight line
Longitudinal Waves - ANSWER -Sound waves are longitudinal
Acoustic Waves - ANSWER -Sound waves are also referred to as
acoustic waves
Acoustic Variables - ANSWER -[ Pressure, Density, & Distance ] Used to
distinguish between sound waves and other types of waves
Pressure - ANSWER -Concentration of force in an area measured in
Pascals (Pa)
Density - ANSWER -Concentration of mass in a volume measured in
kg/cm3
Distance (particle motion) - ANSWER -Measure of particle motion
measured in cm, ft, mile
Acoustic Parameters - ANSWER -There are seven acoustic parameters
pg. 2
,3|Page
Period - ANSWER -Time from the start of one cycle, to the start of the
next cycle measured in microseconds (μs)
Frequency - ANSWER -Number of cycles that occurs in 1 second
measured in Hertz (Hz) 'per second'
Amplitude - ANSWER -Difference between the minimum value & the
average value of the acoustic variable
Power - ANSWER -Rate of energy transfer measured in Watts (W)
Wavelength - ANSWER -Distance or length of one complete cycle
measured in mm, meters, any unit of length
Propagation Speed - ANSWER -Rate at which a sound wave travels
through a medium measured in m/s, mm/μs
Wavelength Formula - ANSWER -wavelength = 1.54 mm/μs
Sound Speed Order - ANSWER -Sound travels fastest in solids, slower in
liquids, & slowest in gases. Order from fastest →slowest: Bone
→Tendon →Muscle →Blood →Liver
Stiffness - ANSWER -Ability of an object to resist compression
pg. 3
, 4|Page
Density & Speed Relationship - ANSWER -Density & speed are inversely
related
Bulk Modulus - ANSWER -Bulk Modulus is the same as stiffness
Speed Determinants - ANSWER -Speed is determined by the density &
stiffness of the medium
Speed Increase with Stiffness - ANSWER -If stiffness increases ↑, speed
increases ↑
Speed Decrease with Density - ANSWER -If density increases ↑, speed
decreases ↓
Speed Formula - ANSWER -Speed = Frequency (Hz) x Wavelength (m)
Pulsed Waves - ANSWER -Pulsed ultrasound has 2 components:
Transmit, talking, or 'on' time and Receive, listening, or 'off' time
Pulsed Duration - ANSWER -Actual time from the start of a pulse, to the
end of a pulse
pg. 4
