Hearing Conservation


Exposure to excessive noise can damage hearing, and it is important to understand the effects of this kind of noise, particularly because such exposure is avoidable.

Noise exposure can be from recreational activities such as hunting or target shooting, to occupational exposures such as noisy industrial machinery and equipment. Sound trauma has a cumulative effect; the more your ears are traumatized by loud noise, the more damage you’ll do. Generally, prolonged exposure to high noise levels over a period of time gradually causes permanent hearing damage.

Noise, or unwanted sound, is one of the most pervasive occupational health problems.

It is a by-product of many industrial processes. Exposure to high levels of noise in the workplace causes hearing loss and may cause other harmful health effects as well. The extent of damage depends primarily on the intensity. The Occupational Safety and Health Administration, (OSHA), may require employers to maintain a hearing conservation program which includes monitoring and audiometric testing. The hearing conservation program requires employers to monitor noise exposure levels in a way that accurately identifies employees exposed to noise at or above 85 dBA averaged over 8 working hours, or an 8-hour time-weighted average (TWA). Employers must monitor all employees whose noise exposure is equivalent to or greater than a noise exposure received in 8 hours where the noise level is constantly 85 dBA. The exposure measurement must include all continuous, intermittent, and impulsive noise within an 80 dBA to 130 dBA range and must be taken during a typical work situation. This requirement is performance-oriented because it allows employers to choose the monitoring method that best suits each individual situation.

In the case of gunshot, a firearm produces a loud burst of sound which is a concussive energy that rattles the ear drum, the bones in the inner ear and the cochlea, a fluid-filled, snail-shaped organ with thousands of tiny hair-like structures that convert sounds from the outside world into electrical impulses the brain can understand. A single gunshot can send 100 decibels down the ear canal, louder than a twin engine airplane.

Whenever a noise source cannot be mitigated, a hearing protection device is the solution. Depending on the application and individual preference, hearing protection can be in the form of over the head ear muffs or earplugs.

There are four general classes of earplugs. These include: pre-molded, formable, custom molded, and semi-insert.

  • Pre-molded earplugs do not require the plug to be formed before it is inserted into the ear. This prevents the plugs from becoming soiled before insertion.
  • Formable earplugs are made of a variety of substances. However, each substance shares the common feature of being able to be shaped by the user prior to insertion. One drawback of this is the obvious need for the user to have clean hands while shaping the earplug. They do have the advantage of forming to the user’s ear, while many pre-molded earplugs do not accomplish this very well.
  • Semi-inserts are generally a soft earplug on the end of band. The band aides in maintaining the earplug in position. They are often useful since they can be quickly removed and inserted.
  • Custom molded ear plugs are unique for each person, since they are cast from each user’s own ear canals. Therefore, they provide a personalized fit for each individual. Custom ear plugs are also available with impulse suppression electronics that protect the user from noise levels above 85 dBA but allow the user to be able to communicate at lower noise levels.

Earmuffs are another type of hearing protection device. The main difference between earmuffs and earplugs is that earmuffs are not inserted inside the ear canal. Instead the muffs create a seal around the outside of the ear to prevent noise from reaching the inner ear. Earmuffs are easy to wear and often provide a more consistent fit than an earplug. There are earmuffs available that use the principle of active noise control to help reduce noise exposures.

Hearing protection in noisy environments is essential to working in a safe and healthful environment and can stimulate innovation and creativity and result in increased performance and higher productivity.