SHS 367 Exam 3 | Complete Practice Questions, Correct
Answers & Detailed Rationales (2026/2027)
Question 1
What fundamental physical properties define a pure-tone sine wave
acoustic signal?
A. Frequency (cycles per second measured in Hertz), amplitude
(intensity/sound pressure), wavelength, and starting phase.
B. Decibel hearing level (dB HL) and pure-tone average (PTA).
C. Impedance, admittance, and static compliance.
D. Fundamental frequency and formant frequency bands.
Correct Answer: A. Frequency (cycles per second measured in Hertz),
amplitude (intensity/sound pressure), wavelength, and starting phase.
Detailed Rationale: A pure tone is a simple harmonic motion wave
completely defined mathematically and acoustically by its frequency,
amplitude, wavelength, and phase.
Question 2
According to the inverse-square law, what happens to sound pressure
level (SPL) when the distance from a point source in a free sound field is
doubled?
A. Sound pressure level decreases by 6 dB (or sound intensity decreases
by a factor of 4).
B. Sound pressure level decreases by 3 dB.
,C. Sound pressure level remains constant regardless of distance.
D. Sound pressure level increases by 6 dB.
Correct Answer: A. Sound pressure level decreases by 6 dB (or sound
intensity decreases by a factor of 4).
Detailed Rationale: In a free field, sound energy spreads over an
expanding spherical surface area, causing sound pressure to halve (a 6
dB reduction) every time distance from the source is doubled.
Question 3
What is the primary difference between decibels sound pressure level
(dB SPL) and decibels hearing level (dB HL)?
A. dB SPL is an objective physical measurement of sound pressure
relative to a universal reference baseline of 20 𝜇Pa, whereas dB HL is
audiometric zero referenced to average normal human hearing
thresholds at each specific frequency.
B. dB HL measures electrical potential while dB SPL measures acoustic
reflex decay.
C. dB SPL is only used for bone conduction testing.
D. There is no mathematical or physiological difference between dB SPL
and dB HL.
Correct Answer: A. dB SPL is an objective physical measurement of
sound pressure relative to a universal reference baseline of 20 𝜇Pa,
whereas dB HL is audiometric zero referenced to average normal
human hearing thresholds at each specific frequency.
,Detailed Rationale: Because human ear sensitivity varies across
frequency, audiometric zero (0 dB HL) normalizes SPL thresholds so that
0 dB HL represents the softest sound an otologically normal young adult
can hear across all frequencies.
Question 4
What physiological mechanism explains the tonotopic organization of
the basilar membrane within the cochlea?
A. The basilar membrane varies systematically in width, mass, and
stiffness from base to apex, causing high-frequency sounds to elicit
maximum displacement at the narrow, stiff basal end and low-
frequency sounds at the wide, flaccid apical end.
B. The outer hair cells secrete potassium ions exclusively at the apical
hook.
C. The tectorial membrane changes length in response to middle ear
muscle contractions.
D. The stapes footplate vibrates at a uniform rate across all cochlear
turns.
Correct Answer: A. The basilar membrane varies systematically in
width, mass, and stiffness from base to apex, causing high-frequency
sounds to elicit maximum displacement at the narrow, stiff basal end
and low-frequency sounds at the wide, flaccid apical end.
Detailed Rationale: Georg von Békésy demonstrated that traveling
waves peak at specific locations along the basilar membrane depending
on frequency due to mechanical gradient properties.
Question 5
, What are the primary anatomical resonant frequencies of the human
outer ear (specifically the concha and ear canal), and what is their
clinical significance?
A. Between 2,000 Hz and 5,000 Hz, which provides natural acoustic
amplification (approximately 10 to 15 dB) to speech sounds critical for
speech recognition.
B. Between 250 Hz and 500 Hz, protecting the ear from low-frequency
wind noise.
C. Exactly 10,000 Hz to 20,000 Hz for ultrasonic echolocation.
D. Between 100 Hz and 500 Hz for middle ear impedance matching.
Correct Answer: A. Between 2,000 Hz and 5,000 Hz, which provides
natural acoustic amplification (approximately 10 to 15 dB) to speech
sounds critical for speech recognition.
Detailed Rationale: The pinna, concha, and ear canal act as acoustic
resonators that boost high-frequency consonant sounds important for
speech understanding.
Question 6
What are the three distinct tissue layers that compose the pars tensa of
the tympanic membrane?
A. Outer cutaneous (epithelial) layer, middle fibrous (lamina propria)
layer, and inner mucosal layer.
B. Cartilaginous layer, bony layer, and adipose layer.
C. Endolymphatic layer, perilymphatic layer, and periosteal layer.
D. Stapedial layer, lenticular layer, and malleolar layer.
Answers & Detailed Rationales (2026/2027)
Question 1
What fundamental physical properties define a pure-tone sine wave
acoustic signal?
A. Frequency (cycles per second measured in Hertz), amplitude
(intensity/sound pressure), wavelength, and starting phase.
B. Decibel hearing level (dB HL) and pure-tone average (PTA).
C. Impedance, admittance, and static compliance.
D. Fundamental frequency and formant frequency bands.
Correct Answer: A. Frequency (cycles per second measured in Hertz),
amplitude (intensity/sound pressure), wavelength, and starting phase.
Detailed Rationale: A pure tone is a simple harmonic motion wave
completely defined mathematically and acoustically by its frequency,
amplitude, wavelength, and phase.
Question 2
According to the inverse-square law, what happens to sound pressure
level (SPL) when the distance from a point source in a free sound field is
doubled?
A. Sound pressure level decreases by 6 dB (or sound intensity decreases
by a factor of 4).
B. Sound pressure level decreases by 3 dB.
,C. Sound pressure level remains constant regardless of distance.
D. Sound pressure level increases by 6 dB.
Correct Answer: A. Sound pressure level decreases by 6 dB (or sound
intensity decreases by a factor of 4).
Detailed Rationale: In a free field, sound energy spreads over an
expanding spherical surface area, causing sound pressure to halve (a 6
dB reduction) every time distance from the source is doubled.
Question 3
What is the primary difference between decibels sound pressure level
(dB SPL) and decibels hearing level (dB HL)?
A. dB SPL is an objective physical measurement of sound pressure
relative to a universal reference baseline of 20 𝜇Pa, whereas dB HL is
audiometric zero referenced to average normal human hearing
thresholds at each specific frequency.
B. dB HL measures electrical potential while dB SPL measures acoustic
reflex decay.
C. dB SPL is only used for bone conduction testing.
D. There is no mathematical or physiological difference between dB SPL
and dB HL.
Correct Answer: A. dB SPL is an objective physical measurement of
sound pressure relative to a universal reference baseline of 20 𝜇Pa,
whereas dB HL is audiometric zero referenced to average normal
human hearing thresholds at each specific frequency.
,Detailed Rationale: Because human ear sensitivity varies across
frequency, audiometric zero (0 dB HL) normalizes SPL thresholds so that
0 dB HL represents the softest sound an otologically normal young adult
can hear across all frequencies.
Question 4
What physiological mechanism explains the tonotopic organization of
the basilar membrane within the cochlea?
A. The basilar membrane varies systematically in width, mass, and
stiffness from base to apex, causing high-frequency sounds to elicit
maximum displacement at the narrow, stiff basal end and low-
frequency sounds at the wide, flaccid apical end.
B. The outer hair cells secrete potassium ions exclusively at the apical
hook.
C. The tectorial membrane changes length in response to middle ear
muscle contractions.
D. The stapes footplate vibrates at a uniform rate across all cochlear
turns.
Correct Answer: A. The basilar membrane varies systematically in
width, mass, and stiffness from base to apex, causing high-frequency
sounds to elicit maximum displacement at the narrow, stiff basal end
and low-frequency sounds at the wide, flaccid apical end.
Detailed Rationale: Georg von Békésy demonstrated that traveling
waves peak at specific locations along the basilar membrane depending
on frequency due to mechanical gradient properties.
Question 5
, What are the primary anatomical resonant frequencies of the human
outer ear (specifically the concha and ear canal), and what is their
clinical significance?
A. Between 2,000 Hz and 5,000 Hz, which provides natural acoustic
amplification (approximately 10 to 15 dB) to speech sounds critical for
speech recognition.
B. Between 250 Hz and 500 Hz, protecting the ear from low-frequency
wind noise.
C. Exactly 10,000 Hz to 20,000 Hz for ultrasonic echolocation.
D. Between 100 Hz and 500 Hz for middle ear impedance matching.
Correct Answer: A. Between 2,000 Hz and 5,000 Hz, which provides
natural acoustic amplification (approximately 10 to 15 dB) to speech
sounds critical for speech recognition.
Detailed Rationale: The pinna, concha, and ear canal act as acoustic
resonators that boost high-frequency consonant sounds important for
speech understanding.
Question 6
What are the three distinct tissue layers that compose the pars tensa of
the tympanic membrane?
A. Outer cutaneous (epithelial) layer, middle fibrous (lamina propria)
layer, and inner mucosal layer.
B. Cartilaginous layer, bony layer, and adipose layer.
C. Endolymphatic layer, perilymphatic layer, and periosteal layer.
D. Stapedial layer, lenticular layer, and malleolar layer.
