Noise is one of the most common of all the occupational hazards. In the United States, for example, more than 9 million workers are exposed to daily noise levels of 85 decibels These noise levels are potentially hazardous to their hearing and can produce other adverse effects as well. There are approximately 5.2 million workers exposed to noise above these levels in manufacturing and utilities, which represents about 35% of the total number of workers in US manufacturing industries.

The noisiest manufacturing environments with the greatest percentages of workers exposed to 90 decibels or more are:

• Lumber and wood
• Textiles
• Petroleum and coal
• Primary metals
• Utilities
• Paper
• Chemicals
• Printing and publishing
• Fabricated metals
• Food
• Machinery
• Transportation equipment
• Furniture and fixtures
• Rubber and plastics
• Tobacco
• Stone, clay and glass
• Electrical machinery
• Apparel
• Leather

Low Frequency Noise

The noise from these machines is predominantly in the low frequencies. Low frequency noise from engines, motors and fans is not easily eliminated with traditional passive hearing protection devices. Low frequency noise waves are long and carry great distances. They can penetrate passive barriers like foam earcups or even cement walls (which is why you can hear the bass of your neighbor’s stereo).