Measure Sound, Protect Hearing

Four million workers do their job each day in environments with damaging noise. Particularly at risk for exposure to dangerous level noise are employees who work in industries like manufacturing, utilities, aviation, construction, mining, transportation, agriculture, and the military. Noise-induced hearing loss is one of the most common occupational diseases and the second most self-reported occupational illness or injury. Long-term exposure to high average noise levels is the number one cause of occupational hearing loss, yet many people are unaware the damage is happening. So what are the warning signs that a workplace may be too noisy?

The noise level in a work environment may be at dangerous levels if employees:

• Experience ringing or humming in their ears after they've left work.
• Have to shout to be heard by a coworker just a few feet away.
• Experience temporary hearing loss after leaving work.
• Have a "fullness" feeling in their ears after leaving a noisy area.
• Can hear people talking but have dificulty understanding them.

Occupational noises can be continuous, noise that remains constant over a given period of time, or intermittent, noise with intervals of quiet and noisy. Inside a typical workplace, noise comes from different sources like machinery, boilers, heavy equipment, tools, and fans. A reaction to a sound can vary from person to person, and one sound may seem louder than another. That's because frequency, the number of times per second that a sound wave cycles from positive to negative to positive again, causes humans to perceive one sound to be louder than another. In other words, the more a sound wave moves the air backwards and forwards, the more the ear drum moves as the sound wave enters the external auditory canal. So two sounds can be of equal intensity but a sound that seems louder does so because it has a different frequency.

The key to preventing noise-induced hearing loss in the workplace is to routinely assess the noise exposure using a sound level meter which measures the amount of noise an individual is exposed to throughout the work day.

Sound level meters can be used to:

• Spot-check personal sound exposure meter (PSEM) performance.
• Determine an employee's noise dose whenever use of a PSEM is unavailable or inappropriate.
• Identify and evaluate individual noise sources for reduction purposes.
• Aid in determining the feasibility of engineering controls for individual noise sources.
• Evaluate hearing protectors.

Institute for Occupational Safety and Health (NIOSH) and the Canadian Centre for Occupational Health and Safety suggest an 85 dBA limit).

The OSHA standard uses a 5 dBA exchange rate. This means that when the noise level is increased by 5 dBA, the amount of time a person can be exposed to a certain noise level to receive the same dose of sound is cut in half. Here is the permissible noise exposure limits set by OSHA:

Operations Managers and safety professionals should include measuring workplace noise and workers' exposure to noise as routine part of their safety program. Sound level meters can help identify work locations where the noise levels are potentially dangerous and the workers than may be affected. Digital, hand-held meters like Testo 815 and Testo 816 are the ideal sound level meter for daily use with max-min value memory, frequency A and C weighting, and built-in tripod knuckle screw. The Testo 816 model has a microphone, stereo jack, on-site calibration option, AC/DC output, and switchable time weighting to better evaluate the noise source. All these features make it ideal for workplace measurements to protect your workers by detecting and reducing occupational noise-induced hearing loss in the workplace.