Research Outline

Noise-Induced Damage to Ears


To provide factors that cause noise-induced damage to ears to help prevent hearing damage to workers.

Early Findings

Noise-Induced Hearing Loss

  • According to the National Institute on Deafness and Other Communication Disorders (NIDCD), noises that are at/above 85 decibels can lead to hearing loss.
  • According to the CDC, loud noises are harmful to the inner ear (cochlea). "A one-time exposure to extreme loud sound or listening to loud sounds for a long time can cause hearing loss".
  • Hair cells in the cochlea enable the brain to detect sounds. "Up to 30% to 50% of hair cells can be damaged or destroyed" before any change in hearing can be measured. Hearing loss is noticed after many of these hair cells have been destroyed.

Factors That Influence Hearing Loss

  • According to the American Speech-Language-Hearing Association (ASHA), the risk of noise-induced hearing loss is influenced by three factors:
    • Noise level
    • The duration that one hears the noise
    • The closeness/proximity to the noise
  • Noise Level is measured by sound-level meters. Noise levels are recorded in decibels or dBA.
  • Sounds at 70 dBA or lower are safe to be listened to for any duration of time.
  • Sounds at 85 dBA can cause ear damage when listened to for more than 8 hours.
  • According to ASHA, "if the sound goes up to 88 dBA, it is safe to listen to those same sounds for 4 hours. And if the sound goes up to 91 dBA", safe listening time is 2 hours.
  • Sounds at 120 dBA or higher are not safe to be listened to for any period of time. These include fireworks (150 decibels), firearms (140 decibels), jackhammer (130 dBA), and a jet plane takeoff (120 dBA).