Understanding Noise-Induced Hearing Loss

Hearing Health, Hearing Loss

Sound is a constant presence in our daily lives. Noise is part of the environments we live, work, and socialize in. Sounds from phones, television, traffic, office chatter, restaurants etc. are typically at levels that do not impact our hearing. But exposure to loud noise can permanently damage critical parts of the auditory system, causing hearing loss. This can develop immediately or gradually at any age and can be the result of one-time or chronic exposure to loud noise. In most cases, noise-induced hearing loss is preventable!

How Hearing Works

The sense of hearing involves a complex process that requires the complete function of our ears. The ears are very sensitive organs that can be divided into three components:

  • Outer Ear: includes the most visible part of the ear (known as the pinna or auricle), and the ear canal.
  • Middle Ear: the ear drum divides the outer and middle ear which consists of three small and connected bones known as the ossicles in addition to the eustachian tube. This canal connects the middle ear to the back of the nose which helps maintain pressure levels in the middle ear (needed to transfer sound).
  • Inner Ear: is comprised of the cochlea (filled with hair cells and fluid) and the auditory nerve

The outer ear absorbs as much sound from the environment as possible and the sound waves travel through the ear canal and lands on the eardrum, causing it to vibrate. This triggers the movement of the ossicles in the middle ear which help push the sound waves further into the ear. The sound waves move the fluid and hair cells in the cochlea which translate the sound waves to electrical nerve impulses that sent to the brain (via auditory nerve) to process.

Impact of Noise on Hearing

Short- or long-term exposure to loud noise can damage your hearing temporarily or permanently depending on the kind of sound and how long a person is exposed to loud noise. Examples of loud noise include:

  • Operating loud machinery
  • Working in a noisy environment (airport, factory, train station etc.)
  • Consistently attending concerts and/or sporting games
  • Frequently wearing headphones or earbuds with the volume on high
  • Hunting, target shooting

Noise induced hearing loss is often caused by damaging the hair cells in the cochlea. Humans are born with thousands of hair cells in each cochlea, these hair cells do not regenerate. This means that we are born with all of the hair cells we will ever have in the cochlea (unlike other cells that do regenerate, skin cells for example). Sound waves absorbed by the outer ear, amplified by the middle ear, cause the hair cells to move up, down, and bend. This is what allows the sound waves to be converted to electrical signals. The louder the sound, the greater the movement and vibration. The constant movement of these hair cells is what causes damage. Many of us have experienced short-term hearing loss as a result of this happening. After leaving a loud event (concert, sporting event) you may notice that it is difficult for you to hear – sounds are muffled, you may be talking louder, there could be ringing in your ears, and you can’t hear soft sounds. This often does not last for a long period of time and your hearing is restored. This is because the hair cells, after being exposed to loud noise (and moving) need time to rest. It is when there is too much movement and vibration triggered by loud noise that these hair cells loose sensitivity and are permanently damaged.

Preventative Tips

There are many useful ways to protect your hearing health and prevent noise induced hearing loss. This includes:

  • Wearing earplugs or earmuffs at loud events and/or at work if there is constant noise
  • Investing in noise-cancellation features on headphones which would allow you to listen to audio at safe levels in both loud and quiet environments
  • Move away from noisy environments when you can (for example, avoiding construction sites by taking alternative routes)
  • Taking listening breaks (from headphone usage, attending loud events)
  • Have your hearing assessed. A hearing test can inform you of any impairment (the type and degree of any loss)