Poor noise discipline is not only harmful, it is expensive. NIOSH reports that an estimated $242 million is spent annually on workers’ compensation for hearing loss disability. The Department of Veterans Affairs spent an estimated $1.39 billion in calculated compensation for major auditory disabilities in FY2010.

Sounds are air pressure variations that are typically a mixture of random, impulsive, and tonal components. An example of a random sound is the “hiss” of wind rushing in an open car window. An impulsive sound is “bang-bang-bang” of a stamping mill. A tonal sound is the droning from a prop plane flying overhead.