Being exposed to high levels of noise can cause permanent hearing loss. Although hearing loss can be prevented, once the damage is done it is irreversible. So taking the correct precautions is important to your long term health and comfort.
Hearing loss from exposure to loud noise causes wear and tear on the hairs and nerve cells in the cochlea (this is what sends sound signals to the brain). When these tiny hairs and cells are damaged or missing the signals are not transmitted effectively to the brain, which causes the loss of higher pitched tones and make it difficult to pick out certain words when background noise is also present.
It may seem obvious that a one-time exposure to a loud sound, like an explosion, can instantly damage your hearing. It is far more common that long term exposure can lead to a gradual loss of hearing. While a long term exposure is painless, it is still permanent.
Action Limit: The maximum allowable decibel level before hearing protection is required is 85 dBA.
1926.52(b) When employees are subjected to sound levels exceeding those listed in Table D-2 of this section, feasible administrative or engineering controls shall be utilized. If such controls fail to reduce sound levels within the levels of the table, personal protective equipment as required in subpart E, shall be provided and used to reduce sound levels within the levels of the table.
This chart is saying, if you work in an area that produces 95 decibels, you can only work there unprotected for 4 hours per day.
How to Measure Noise Levels
- A Sound Level Meter – handheld device with a microphone that measures the real time noise level.
- Dosimeter – measures and documents the noise level over time to produce and average. This is the best way to figure out the Time Weighted Average for a work day to reference the chart above.
- Personal Noise Indicator – A warning device that alerts over 85 dBA.
- Phone App – NIOSH has a free app, assuming your phone microphone is in good working order.
- The 3 ft rule – If you can stand 3’ away and hold a normal conversation you are probably less than 85 dBA. If you have to raise your voice or lean in to hear, chances are you are over 85.
Hierarchy of Controls
Engineering – When you absolutely have to work near the noise, the most effective way to protect yourself and others from excessive noise is to use sound barriers, enclosures, mufflers, or silencers on equipment.
Administrative – Creating and enforcing rules to maintain a set distance from the noise. For example, a sign that reads “No working within 20 feet of this machine”
Personal Protective Equipment – The last line of defense, but often the best option for construction is to wear PPE. Earplugs or noise canceling muffs, as long as they are worn properly, can greatly reduce the risks of hearing loss.
Here are a few Toolbox Talks related to this topics: Hierarchy of Controls, Hard Hats, Table Saws