Noise-Induced Hearing Loss

Noise-Induced Hearing Loss

Sounds are all around us in our environments. Most sounds such as the television, phone ringing or household appliances may be at a safe level in terms of volume, however, sounds can be harmful when they are too loud. These sounds can damage sensitive structures in our inner ear, which can cause noise-induced hearing loss. This can be temporary or permanent damage of the inner ear, depending on the type of noise and length of time you were exposed to that loud sound.

How do we hear?

There are a series of events that occur before we hear. Sound waves enter our outer ear and travel down the ear canal to the eardrum. The sound wave hits our eardrum causing the eardrum to vibrate. This vibration sets three bones behind the eardrum into motion. These tiny bones of the middle ear are called ossicles (malleus, incus, and stapes). The ossicles vibrate and in turn, create movement of the fluid in the inner ear. The snail like structure of the inner ear is called the “cochlea”. Once the fluid of the cochlea is set into motion, changes in the tiny hair cells of the inner ear are in effect. The movement of the hair cells send electrical signals from the inner ear up the auditory nerve to the brain. The brain then interprets the electrical signals as sound.

Most noise-induced hearing loss is caused by damage to the hair cells of the inner ear. If you are exposed to loud sounds slowly, you may gradually lose your hearing. Since noise-induced hearing loss can occur over time, individuals might not notice it and may ignore the signs of hearing loss until they become more pronounced. Over time, sounds may be distorted, muffled, or the individual may find it difficult to understand people talking. Alternatively, exposure to one loud burst of sound, such as an explosion or gunshot can rupture the eardrum, which can cause immediate permanent hearing loss. Loud noise exposure can cause tinnitus, which is the perception of ringing or buzzing in the ears/head, when no external sound is present.

Sounds are measured in decibels. Sounds that are lower than 75 decibels are unlikely to cause hearing loss. Repeated exposure to sounds at or above 85 decibels can cause hearing loss. The National Institute for Occupational Safety and Health (NIOSH) has recommended that all worker exposures to noise should be controlled below a level equivalent to 85 dBA for eight hours to minimize occupational noise induced hearing loss. In comparison: familiar sounds, such as normal conversation level, is 60 decibels; noise from heavy city traffic is 85 decibels; lawn mower is 90 decibels; motorcycles are 95 decibels; sirens are 120 decibels; and firearms/firecrackers are 150 decibels.

How can you prevent Noise-Induced Hearing loss? 

  • Be aware of hazardous noises in the environment.
  • Know which noises are at or above 85 decibels that can cause hearing loss.
  • Wear hearing protection or earplugs around loud noises (recreational or work related). If you are in noisy environments for long periods of time and are interested in custom hearing protection, please see our Custom Noise Protection page.
  • Have your hearing tested or monitored if you are exposed to noise either recreationally or on a regular basis.

If you have any questions, please contact HEARING HEALTHCARE of East Gwillimburyand book a complimentary hearing test today!

Call (905) 478-2929


Additional resource:

Canadian Centre for Occupational Health and Safety