Noise-Induced Hearing Loss (NIHL)

During noise exposure there is a cascade of events inside the cochlea damaging both the hair cells and the supporting cells inside the inner ear. The damage is not just due to mechanical damage to the cochlear cells but also chemical processes triggered by noise.  Research has identified that this process is ongoing for up to 7 to 10 days following noise exposure.  Additionally, a very loud sound can cause acoustic trauma in a single event such as permanent damage to the inner ear, or can damage the ear drum or the middle ear bones.


When exposed to loud sounds a noise-induced temporary threshold shift is the first effect experienced.  This is a temporary decrease in hearing that may be accompanied by tinnitus, ringing in the ears.  This decrease in hearing may last anywhere from minutes to days depending on the volume of the noise and duration of exposure.  Over time and with repeated noise exposure the ear is unable to recover from temporary threshold shifts and permanent damage occurs.

Noise induced hearing loss occurs when there has been exposure to a loud sound for a prolonged period of time.  As a sound increases in volume the time permitted to spend in that environment decreases.  This is referred to as the time-intensity trade off.

When you are unsure whether or not a certain noise has the potential to harm your hearing there are a couple of things to keep in mind.  Noise may be too loud if:

  • You need to raise your voice to be heard
  • The noise hurts your ears
  • Your ears are ringing from the noise
  • Everything sounds muffled after noise exposure

In Canada, regulations have been set to prevent noise induced hearing loss. Nova Scotia noise regulations are based on the following:

dB Time Table

We all know that working in industrial settings can be noisy but what about all the other sounds around us?  It is important to remember that hearing loss is not just from working in a noisy place but may be from hobbies as well.  Often we think about occupational noise exposure and recreational noise exposure as two separate concepts however, what may be occupational to one person may be recreational to another.  Additionally, those who work in noise need to be careful about activities done outside the workplace as they can contribute to noise exposure.

dB Table

Anyone exposed to noise, whether occupational or during leisure activities, should add a hearing test to their health and wellness checklist. A baseline assessment establishes your hearing levels and can be used to monitor changes as they occur. It is important to know your hearing health status.
- Dr. Patricia Cameron, Audiologist



At Hearing Institute Atlantic we share a deep commitment to the highest quality of hearing care. We understand that hearing connects us; to people and places, to the things we love to do. That’s why we offer affordable solutions that are comfortable, discreet and packed with technology. If you have concerns about your hearing health visit our team of trusted professionals.