The American Tinnitus Association is the foremost organization committed to preventing and curing tinnitus. They have extensive information on tinnitus, which impacts up to 50 million people in the United States and millions more worldwide. Most commonly caused by noise exposure, tinnitus drastically reduces quality of life for 250 million people worldwide.
The Better Hearing Institute has extensive resources on hearing loss, causes and resources. It also has a Hearing Loss Simulator that has different situations and what it 'sounds like' to people with hearing loss.
The National Institute for Occupational Safety and Health has extensive information about workplace regulations for noise levels and sponsors the Dangerous Decibels Project. The project is a public health campaign to reduce Noise Induced Hearing Loss (NIHL) and tinnitus (ringing in the ear) by changing knowledge, attitudes, and behaviors.