EHS has developed a Hearing Conservation Program (HCP) to comply with OSHA regulations, and to coordinate efforts to reduce occupational noise exposures and prevent occupational hearing loss. All employees with an 85 dbA Time Weighted Average (TWA) or higher must attend hearing conservation training annually and receive an annual audiogram.  Hearing protection devices must comply with ANSI standards.(


  • Excessive Noise
  • Ultrasound (High Frequency)

General Requirements

All University employees with noise exposures equal or exceeds an 8-hour time weighted average (TWA) of 85 decibels are enrolled in a HCP.  A general rule of thumb for detecting excessive noise levels is if you have to raise your voice when talking to someone 3 feet away. The key elements of the Hearing Conservation Program include:

  • EHS must conduct noise measurements to determine if employees are being overexposed to noise, and to identify the machine(s) or work process(s) that are contributing to the exposure.
  • If a worker is exposed to an excessive amount of noise, measurements are needed to determine the proper hearing protection device (HPD) that should be used.
  • A Noise Exposure Hazard Assessment Form should be used to determine if employees/staff need to be in NCSU’s Hearing Conservation Program and/or if noise level monitoring is needed

Types of Hearing Protection Devices (HPD)

To prevent noise-induced hearing loss, hearing protection devices must reduce noise exposure to time-weighted average (TWA) levels of 90 dbA or below, or to 85 dbA or below for those workers who have suffered a standard threshold shift (STS). HPDs reduce the amount of noise; however, they cannot eliminate all of the noise reaching the ear since noise can take many routes into the ear. The two most commonly used are:

  • Ear plugs are inserted into the ear canal to reduce the amount of noise that reaches the ear via that route. Ear plugs when placed in the ear correctly, will expand to fill the ear canal and seal against the walls of the ear.  This allows foam ear plugs to fit ear canals of different sizes.  There are two types of ear plugs disposable and reusable.
  • Ear muffs are devices that fit against the head and enclose the entire external ears. The inside of the muff cup is lined with an acoustic foam which can reduce noise by as much as 15 to 30 decibels. Ear muffs are often used in conjunction with ear plugs to protect the employee from extremely loud noises, usually at or above 105 decibels.
  • Specific Hearing Protection Devices (HPD)guidance can be found on the EHS website.


EHS will make recommendations for appropriate hearing protection devices (HPD) for individuals based on noise attenuation requirements and HPD fittings. If you are not already enrolled in the Hearing Conservation Program, contact EHS for more information. Those already enrolled in the program will be notified by EHS to attend annual training and testing.  Choosing the right hearing protector depends upon several factors.

  • Good seal: Sound reduction is dependent upon blocking any air leakage which will allow sound to bypass the hearing protector and enter the ear. For this reason, the hearing protector must fit properly whether over the ear or in the ear.
  • Comfort: Both comfort and convenience are important if the device is to be used consistently. The ease of placing and removing the device, as well as environmental factors such as the presence of dirt or chemicals must be considered.
  • Communication: Hearing protectors often make communication difficult by reducing and distorting sounds. Employees who are hearing-impaired who must receive detailed face to face instruction may prefer ear muffs so that they can lift up the muffs to hear speech.

Storage and Care

  • Follow manufacturer’s recommendations for storage, use, and care.
  • Ear plugs must be replaced whenever they become soiled. Using an unclean ear plug may lead to an ear infection. Employees should be issued their own ear muffs, however, if ear muffs are used by more than one employee, the ear muffs should be cleaned frequently. Ear muffs should be wiped off with soap and water.
  • Ear muffs should be inspected regularly for signs of wear and tear, and should defects appear, the device should be replaced.
  • Always follow the manufacturer’s recommendation for inspection.