Sound Levels

The OSH Act of 1970 established NIOSH, which is part of the CDC as a research agency focused on the study of safety and health in the workforce. NIOSH recommends that workers wear hearing protection whenever the noise is equal to or greater than 85 dBA for an eight-hour TWA (time-weighted average). Below is a helpful chart to help understand dangerous noise levels and your maximum time exposure.

Signs of Hearing Loss

These symptoms can be a sign of hearing loss caused by noise:

• Sounds seem muffled, especially speech.
• High-pitched sounds like doorbells, telephones, and alarm clocks are hard to hear.
  
• Conversations are difficult to understand in crowded noisy environments like a restaurant.
  
• Difficult to understand conversations over the phone.
  
• Hard to distinguish speech consonants, such as “s” and “f”, or “sh” and “th”.
  
• Find yourself asking others to speak more slowly and clearly a lot.
  
• Find yourself asking others to speak louder or repeat what was said a lot.
  
• You turn up the volume of devices a lot.
  
• You have ringing in the ears.
  
• You have hypersensitivity to certain sounds, which can create pain.
  

Noise pollution can cause other health problems:

• Anxiety: Noise can cause stress, which leads to anxiety, sleep dysfunctions, and fatigue.
• Heart Disease: Noise and stress can elevate blood pressure, support heart disease and increase your heart rate.
• Pregnancy: Noise can damage a newborn’s hearing.
  
• Learning: Noisy environments can interfere with a child’s development.
  
• Depression: Hearing loss can lead to social isolation and depression.
  

If you have signs of hearing loss you should get tested by a qualified healthcare provider. Prevention and early detection of hearing loss is very important. It is common for hearing loss to occur gradually. About one third Americans between the ages of 65 and 75 have some degrees of hearing loss. 75 and older is one out of two. Aging and chronic exposure to loud noises contribute to hearing loss, and you can’t reverse most types of hearing loss. Regular check-ups can help identify hearing loss early.

Hearing Protective Devices (HPDs)

HPDs decrease the intensity of noise that reaches the eardrum. They come in two forms: earplugs and earmuffs. Simultaneous use of earplugs and earmuffs can add 10 to 15 dB more protection. Wearing both earplugs and earmuffs should be used for noise greater than 105 dB.

Earplugs

Earplugs are small expandable inserts that fit into the outer ear canal. They are only effective when they completely block the ear canal with an airtight seal. They come in a variety of shapes and sizes. Earplugs are better for low frequency noise.

Earmuffs

These devices fit against the head and enclose the whole external ear. Earmuffs have the same NRR as do with earplugs. Earmuffs can work on their own but are usually doubled up with earplugs to protect with extremely loud noises (above 105 decibels). Earmuffs are better for high frequency noise. Note that earmuffs will not seal around eyeglasses or long hair, and the adjustable headband tension must be sufficient to hold the earmuffs firmly around the ear. Personal music players are not are not a form of hearing protection. Frequent and extended exposure to sound in excess of 85 decibels can cause long-term hearing loss. Some personal music players can reach more than 115 decibels, representing significant potential for damage in a few minutes.

Noise Reduction Rating (NRR)

The NRR is a unit of measurement used to determine the effectiveness of HPDs to decrease sound exposure within a given working environment. HPDs are classified by their potential to reduce noise in decibels (dB), and are tested and approved by the American National Standards (ANSI) in accordance with the Occupational Safety and Health Administration (OSHA). The higher the NRR number the higher the potential of noise reduction.

Earplugs and earmuffs will usually come with a Noise Reduction Rating (NRR). They can range from 22 NRR up to 33 NRR. If your earplug is a 33 NRR, this does not mean you will get 33 db of protection. Unfortunately, you will have to do a little math. To know how many decibels you are being protected from (with varying degrees of accuracy), subtract 7 from the NRR, then divide by 2. Subtract the value from the noise.

Example: For 110 dBA: Night Club (with music) using a 33 NRR rated earplug.

1. 33 - 7 = 26
2. 26 / 2 = 13
   
3. 110 - 13 = 97 dB
   

Hearing Protection