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EDELMAN SPI EXAM REVIEW TEST – ARDMS
SONOGRAPHY PRINCIPLES & INSTRUMENTATION
| 2026/2027 QUESTIONS WITH VERIFIED ANSWERS
AND PHYSICS RATIONALES STUDY GUIDE.
DOMAIN 1: PERFORMING ULTRASOUND EXAMINATIONS (Questions 1-25)
Q1. What is the speed of sound in soft tissue?
A. 330 m/s
B. 1540 m/s [CORRECT]
C. 4080 m/s
D. 13 m/s
Correct Answer: B
Rationale: The average propagation speed of ultrasound in soft tissue is 1540 m/s (or 1.54
mm/μs). This value is essential for calculating wavelength, determining imaging depth, and
proper TGC settings.
Q2. [Calculation] A 5 MHz transducer is used for an abdominal examination. What is the
wavelength in soft tissue?
A. 0.31 mm [CORRECT]
B. 0.51 mm
C. 0.77 mm
D. 1.54 mm
Correct Answer: A
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Rationale: Wavelength (mm) = 1.54 / Frequency (MHz) = 1. = 0.308 mm ≈ 0.31 mm.
Higher frequencies produce shorter wavelengths, resulting in improved axial resolution but
decreased penetration.
Q3. Which of the following is determined solely by the medium through which sound travels?
A. Frequency
B. Period
C. Amplitude
D. Propagation speed [CORRECT]
Correct Answer: D
Rationale: Propagation speed is determined by the properties of the medium (stiffness and
density). Frequency and period are determined by the sound source (transducer). Amplitude
is determined by both.
Q4. [Calculation] If the frequency of a sound wave is 2 MHz, what is the period?
A. 0.5 μs [CORRECT]
B. 2.0 μs
C. 0.5 ms
D. 0.2 μs
Correct Answer: A
Rationale: Period is the reciprocal of frequency. T = 1/f. Frequency = 2,000,000 Hz. Period = 1 /
2,000,000 seconds = 0.0000005 seconds = 0.5 microseconds (μs).
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Sub-Topic: Propagation principles (4 questions)
Q5. What is the acoustic impedance of a medium?
A. The speed of sound divided by density
B. The density multiplied by the propagation speed [CORRECT]
C. The frequency multiplied by the wavelength
D. The resistance to electrical flow
Correct Answer: B
Rationale: Acoustic impedance (Z) is defined as the product of the density (ρ) of the medium
and the propagation speed (c) of sound in that medium (Z = ρ × c). It is measured in Rayls.
Q6. Sound travels fastest in which of the following media?
A. Air
B. Water
C. Soft tissue
D. Bone [CORRECT]
Correct Answer: D
Rationale: Propagation speed is determined by stiffness and density. Bone has the highest
stiffness, resulting in the fastest propagation speed (approx. 4080 m/s), followed by soft
tissue (1540 m/s), water (1480 m/s), and air (330 m/s).
Q7. What occurs at the interface between two media with different acoustic impedances?
A. Refraction
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B. Reflection [CORRECT]
C. Absorption
D. Scattering
Correct Answer: B
Rationale: Reflection occurs at the boundary between two media with different acoustic
impedances. The fraction of sound reflected depends on the impedance mismatch. Refraction
requires different speeds and an oblique angle.
Q8. Which term describes the bending of a sound wave as it passes through media with
different propagation speeds at an oblique angle?
A. Reflection
B. Scattering
C. Refraction [CORRECT]
D. Diffraction
Correct Answer: C
Rationale: Refraction is the change in direction of a sound wave as it crosses a boundary
between media with different propagation speeds at an angle other than 90 degrees. It
follows Snell's Law.
Sub-Topic: Attenuation mechanisms (4 questions)
Q9. Which of the following interactions of sound with tissue causes the greatest attenuation
in soft tissue?
A. Reflection
EDELMAN SPI EXAM REVIEW TEST – ARDMS
SONOGRAPHY PRINCIPLES & INSTRUMENTATION
| 2026/2027 QUESTIONS WITH VERIFIED ANSWERS
AND PHYSICS RATIONALES STUDY GUIDE.
DOMAIN 1: PERFORMING ULTRASOUND EXAMINATIONS (Questions 1-25)
Q1. What is the speed of sound in soft tissue?
A. 330 m/s
B. 1540 m/s [CORRECT]
C. 4080 m/s
D. 13 m/s
Correct Answer: B
Rationale: The average propagation speed of ultrasound in soft tissue is 1540 m/s (or 1.54
mm/μs). This value is essential for calculating wavelength, determining imaging depth, and
proper TGC settings.
Q2. [Calculation] A 5 MHz transducer is used for an abdominal examination. What is the
wavelength in soft tissue?
A. 0.31 mm [CORRECT]
B. 0.51 mm
C. 0.77 mm
D. 1.54 mm
Correct Answer: A
, 2
Rationale: Wavelength (mm) = 1.54 / Frequency (MHz) = 1. = 0.308 mm ≈ 0.31 mm.
Higher frequencies produce shorter wavelengths, resulting in improved axial resolution but
decreased penetration.
Q3. Which of the following is determined solely by the medium through which sound travels?
A. Frequency
B. Period
C. Amplitude
D. Propagation speed [CORRECT]
Correct Answer: D
Rationale: Propagation speed is determined by the properties of the medium (stiffness and
density). Frequency and period are determined by the sound source (transducer). Amplitude
is determined by both.
Q4. [Calculation] If the frequency of a sound wave is 2 MHz, what is the period?
A. 0.5 μs [CORRECT]
B. 2.0 μs
C. 0.5 ms
D. 0.2 μs
Correct Answer: A
Rationale: Period is the reciprocal of frequency. T = 1/f. Frequency = 2,000,000 Hz. Period = 1 /
2,000,000 seconds = 0.0000005 seconds = 0.5 microseconds (μs).
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Sub-Topic: Propagation principles (4 questions)
Q5. What is the acoustic impedance of a medium?
A. The speed of sound divided by density
B. The density multiplied by the propagation speed [CORRECT]
C. The frequency multiplied by the wavelength
D. The resistance to electrical flow
Correct Answer: B
Rationale: Acoustic impedance (Z) is defined as the product of the density (ρ) of the medium
and the propagation speed (c) of sound in that medium (Z = ρ × c). It is measured in Rayls.
Q6. Sound travels fastest in which of the following media?
A. Air
B. Water
C. Soft tissue
D. Bone [CORRECT]
Correct Answer: D
Rationale: Propagation speed is determined by stiffness and density. Bone has the highest
stiffness, resulting in the fastest propagation speed (approx. 4080 m/s), followed by soft
tissue (1540 m/s), water (1480 m/s), and air (330 m/s).
Q7. What occurs at the interface between two media with different acoustic impedances?
A. Refraction
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B. Reflection [CORRECT]
C. Absorption
D. Scattering
Correct Answer: B
Rationale: Reflection occurs at the boundary between two media with different acoustic
impedances. The fraction of sound reflected depends on the impedance mismatch. Refraction
requires different speeds and an oblique angle.
Q8. Which term describes the bending of a sound wave as it passes through media with
different propagation speeds at an oblique angle?
A. Reflection
B. Scattering
C. Refraction [CORRECT]
D. Diffraction
Correct Answer: C
Rationale: Refraction is the change in direction of a sound wave as it crosses a boundary
between media with different propagation speeds at an angle other than 90 degrees. It
follows Snell's Law.
Sub-Topic: Attenuation mechanisms (4 questions)
Q9. Which of the following interactions of sound with tissue causes the greatest attenuation
in soft tissue?
A. Reflection
