Mustafa Kamal Usmani, Nazia Mumtaz, Ghulam Saqulain.
Hearing protective devices and its role in Noise induced hearing loss: an interventional study..
J Pak Med Assoc Jan ;70(3):519-22.

This Quasi experimental study was conducted with the objective to determine the effectiveness of preventive measures including awareness programme and use of hearing protective devices (HPDs) for the prevention and control of Noise Induced Hearing Loss among Oil and Gas field workers from January 2015 to March 2016. A total of 120 workers were selected by convenient sampling, and subjected to pure tone audiometry (PTA) to obtain hearing thresholds followed by intervention with HPDs and retesting a year later. The Mean pure tone thresholds on first visit was 21.19±11.60 dB in right and 24.66±13.26 dB in left ear, while means at second visit (after one year) were 20.65±10.44 dB and 21.45±11.74 dB for the right and left ears respectively with statistically significant difference (p=0.001) for the left ear on t-test. However the difference of frequency and percentage of the participants with normal and reduced hearing at both visits was significant (chi square P=0.001). Hearing protective devices (HPDs) are an effective means to prevent NIHL in workers of oil and gas fields.

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