Frequently Asked Questions - Hearing Conservation Program

What is sound?

Sound is a change in pressure in a solid, liquid, or gas. In order to be heard, the sound must be at a frequency within the range of hearing and have enough energy to stimulate the hearing organs through vibration. In humans, the frequency range is between 20-20,000 Hertz. Humans can typically hear sounds as low as 10 decibels (dB). This is around the level of normal breathing or a soft whisper. Without hearing protection, we can tolerate up to 130 dB for a very short period, about the level of a jackhammer or jet engine at takeoff.

What is noise?

Noise is usually defined as unwanted sound. Depending on the frequency and intensity, noise can be considered hazardous or a nuisance.

How is noise measured?

Noise is measured using a dosimeter for personal noise exposure and/or a sound level meter for area monitoring. Noise is measured on a weighted scale, called the A-scale. The A-scale attempts to mimic human hearing. Noise measured on the A-scale is reported as dBA.

What levels are hazardous?

Like other types of energy, the closer and longer you’re exposed to high noise levels, the greater the risk of damage. Over an 8-hour workday, the Occupational Safety and Health Administration (OSHA) considers 90dBA to be hazardous. At this level for 8 hours per day, hearing damage can be irreversible if the proper steps are not taken. As noise levels increase, the time you can be exposed to that noise decreases. At 110bBA, about the sound of an ambulance siren, the allowable exposure time is 30 minutes per day.

What can I do to protect my hearing?

There are several controls that can be put in place to control hazardous noise, from noise isolation to hearing protectors. The first step is to contact Environmental Health & Radiation Safety (2-2520) to have an assessment of your work area done. EHRS can make recommendations to reduce the levels of hazardous noise.