CAOHC EXAM AND PRACTICE EXAM NEWEST 2025
TEST BANK| COMPLETE 550 REAL EXAM QUESTIONS
AND CORRECT VERIFIED ANSWERS/ ALREADY
GRADED A+| CAOHC CERTIFICATION EXAM PREP
2025 (BRAND NEW!!)
1. A sound wave travels through air by causing:
A) Electron flow
B) Ion displacement
C) Molecular compression and rarefaction
D) Photon vibration
Answer: C
Rationale: Sound in air is a longitudinal wave with alternating high-
pressure (compression) and low-pressure (rarefaction) regions.
2. The frequency of a sound is measured in:
A) Decibels (dB)
B) Hertz (Hz)
1
,C) Pascals (Pa)
D) Watts/m²
Answer: B
Rationale: Frequency (pitch) is cycles per second = Hertz. dB
measures intensity.
3. A doubling of sound pressure level (SPL) corresponds to
approximately:
A) 1 dB increase
B) 3 dB increase
C) 6 dB increase
D) 10 dB increase
Answer: C
*Rationale: Doubling SPL = +6 dB; doubling perceived loudness
~ +10 dB.*
4. Which frequency range is most critical for speech
intelligibility?
2
,A) 125–250 Hz
B) 250–2000 Hz
C) 2000–6000 Hz
D) Above 8000 Hz
Answer: C
*Rationale: Consonant sounds (high frequency 2-6 kHz) carry
meaning; vowels are lower frequency.*
5. The unit used to measure sound intensity level (SIL) relative to
a reference is:
A) dBA
B) dB SPL
C) dB HL
D) dB SL
Answer: B
Rationale: dB SPL is physical sound pressure level; dB HL is hearing
level (audiometric zero).
3
, 6. A 90 dBA TWA (8-hour) is equivalent to what dose?
A) 50%
B) 100%
C) 200%
D) 400%
Answer: B
*Rationale: OSHA 1910.95: 90 dBA = 100% dose (criterion
level).*
7. A 3-dB exchange rate means:
A) Doubling time reduces exposure by 3 dB
B) Halving exposure time permits 3 dB higher level
C) 3 dB increase requires halving exposure time
D) 3 dB = 100% dose
Answer: C
*Rationale: OSHA uses 5 dB; NIOSH/ACGIH use 3 dB (more
protective). 3 dB exchange: each +3 dB requires ½ time.*
4
TEST BANK| COMPLETE 550 REAL EXAM QUESTIONS
AND CORRECT VERIFIED ANSWERS/ ALREADY
GRADED A+| CAOHC CERTIFICATION EXAM PREP
2025 (BRAND NEW!!)
1. A sound wave travels through air by causing:
A) Electron flow
B) Ion displacement
C) Molecular compression and rarefaction
D) Photon vibration
Answer: C
Rationale: Sound in air is a longitudinal wave with alternating high-
pressure (compression) and low-pressure (rarefaction) regions.
2. The frequency of a sound is measured in:
A) Decibels (dB)
B) Hertz (Hz)
1
,C) Pascals (Pa)
D) Watts/m²
Answer: B
Rationale: Frequency (pitch) is cycles per second = Hertz. dB
measures intensity.
3. A doubling of sound pressure level (SPL) corresponds to
approximately:
A) 1 dB increase
B) 3 dB increase
C) 6 dB increase
D) 10 dB increase
Answer: C
*Rationale: Doubling SPL = +6 dB; doubling perceived loudness
~ +10 dB.*
4. Which frequency range is most critical for speech
intelligibility?
2
,A) 125–250 Hz
B) 250–2000 Hz
C) 2000–6000 Hz
D) Above 8000 Hz
Answer: C
*Rationale: Consonant sounds (high frequency 2-6 kHz) carry
meaning; vowels are lower frequency.*
5. The unit used to measure sound intensity level (SIL) relative to
a reference is:
A) dBA
B) dB SPL
C) dB HL
D) dB SL
Answer: B
Rationale: dB SPL is physical sound pressure level; dB HL is hearing
level (audiometric zero).
3
, 6. A 90 dBA TWA (8-hour) is equivalent to what dose?
A) 50%
B) 100%
C) 200%
D) 400%
Answer: B
*Rationale: OSHA 1910.95: 90 dBA = 100% dose (criterion
level).*
7. A 3-dB exchange rate means:
A) Doubling time reduces exposure by 3 dB
B) Halving exposure time permits 3 dB higher level
C) 3 dB increase requires halving exposure time
D) 3 dB = 100% dose
Answer: C
*Rationale: OSHA uses 5 dB; NIOSH/ACGIH use 3 dB (more
protective). 3 dB exchange: each +3 dB requires ½ time.*
4
