How much noise may cause mechanical damage?

Appeared in: NCL (MP) Nursing Officer - 2020

Explanation

Exposure to extremely high noise levels, around 140-150 dB, can cause immediate and permanent mechanical damage to the ear's delicate structures.
This type of injury is known as acoustic trauma and results from a single, brief exposure to an intense sound like an explosion or a jet engine at close range.
The damage involves the physical destruction of hair cells in the organ of Corti within the cochlea, leading to irreversible sensorineural hearing loss.

Option B: This is the sound level of a normal conversation and is considered safe, posing no risk of hearing damage.
Option C: This level is recognized as the threshold of pain and causes immediate discomfort. However, it is less likely to cause instantaneous mechanical destruction compared to the much higher intensity of 150 dB.
Option D: This is the occupational exposure limit for an 8-hour workday. Prolonged or repeated exposure above this level causes gradual, cumulative hearing loss over time, not immediate mechanical damage.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Noise-induced hearing loss and acoustic trauma as background academic context rather than a clinical decision trigger.
Nurses, especially in occupational health, play a key role in educating workers about the dangers of noise exposure and enforcing hearing protection policies in environments where noise levels exceed 85 dB.
Screening for noise-induced hearing loss through regular audiometry is a critical preventive health measure for at-risk populations, such as factory workers, musicians, and airport ground staff.
What if? If the question had asked for the noise level that requires hearing protection for an 8-hour workday according to OSHA, the correct answer would have been '>85 decibel'.

How to Approach the Question

First, identify the keywords in the question: 'mechanical damage' and 'noise'.
Recognize that 'mechanical damage' implies an immediate, physical injury from a single event, which is different from gradual hearing loss that occurs over time.
Recall or deduce the effects of different decibel (dB) levels on the ear.
Evaluate each option: 60 dB is quiet (normal conversation), >85 dB is the threshold for long-term risk, and 120 dB is the threshold for pain.
Conclude that 150 dB represents an extremely intense sound, consistent with the force required for acoustic trauma and immediate mechanical damage.

Concept Tested & Keywords

Q6Jca25LtTJrQJ8HJ_fT0y

E6 Psychology Baron Misra 5e Part 1 p. 125-127

E6 Medicine Harrison 22e Part 1 p. 292-294

E6 Nursing Brunner Adult Health 3SA Vol 2 Part 1 p. 63-65

Practise the full NCL (MP) Nursing Officer - 2020

Attempt every question from this paper in a timed mock, then review the full solution for each one.