How many industrial workers experience NIHL?

While less than 10% of the general population is hearing impaired, 50% of carpenters and plumbers—and 90% of retiring coal mine industry workers—have NIHL.

Answer Extra: 

NIHL is a risk in a wide range of work environments, but workers in some industries have higher exposures to dangerous levels of noise. These industries include: agriculture, mining, construction, manufacturing, utilities, transportation and the military.

source: 
source: NIOSH Pub. No. 2001-103