Noise-Induced Hearing Loss

Man and woman at a construction site. If they don't wear ear protection they may experience noise-induced hearing loss

In our daily lives, we experience a wide range of noises from the environment such as the traffic on the street or sound from the television and radio. These noises are generally not harmful to our hearing. However, being exposed to loud noises is a common cause of hearing loss in adults and can cause damage to the sensitive cells within the hearing system. As its name suggests, noise-induced hearing loss (NIHL) is caused by exposure to “noise” that is loud enough to cause a hearing loss. NIHL may be caused by exposure to loud noise for a brief period, or over a prolonged period. The effects of NIHL may be temporary or permanent and may affect either one ear or both ears.

What causes noise-induced hearing loss?

NIHL can be caused by being exposed to an environment in which loud noise is present for a prolonged period of time, such as working in a manufacturing plant, or by exposure to a loud sound once-off, such as the firing of an air-rifle. Recreational exposure to loud sounds may also cause an NIHL, such as listening to music above safe levels through earphones, attending loud concerts frequently, hunting or shooting practice, or doing handy work around the home with power tools.

What are the effects of noise-induced hearing loss?

The effects of a noise-induced hearing loss on the hearing system are dependent on how long the exposure to the noise is, and how close the listener is to the source of the noise. If it is once-off exposure to intensely loud noise, it may cause damage to the eardrum, the small bones behind the eardrum as well as damage to the cells in the ear responsible for the understanding of sound. Prolonged exposure to loud noise may cause damage to the cells in the ear only and may worsen if continuous exposure occurs.

The effects of noise affect the cell’s ability to understand high frequencies well. This means that individuals with noise-induced hearing loss are still able to hear low-pitched sounds well but experience difficulties with higher-pitched sounds. This is especially important for hearing speech sounds, as many of the consonants from the alphabet, such as “f”, “t”, and “s” are high-pitched sounds. High pitched speech sounds may sound muffled and be unclear to hear. Exposure to noise that may have caused damage to the structures in the ear will cause pain and discomfort. Sometimes, individuals exposed to noise may also experience tinnitus – which is a ringing, buzzing, or roaring sound in the ear.

How is a noise-induced hearing loss treated?

As mentioned, a noise-induced hearing loss may be temporary or permanent. It is often considered to be temporary when exposure to an intense noise is experienced in a single encounter. The effects of a temporary hearing loss generally disappear after 16 – 48 hours, but the long-term effects of damage to the hearing system because of noise, may remain and be experienced later in life. Permanent damage to the hearing system is due to the destruction of the cells in the ear that cannot be regenerated.

Diagnosis of noise-induced hearing loss is done with a hearing test. The hearing test identifies the ability of an individual to hear sounds that are low, mild, and high in frequency. If the eardrum and bones behind the eardrum are also damaged because of the loss, a loss of ability to hear is generally seen across the low to the high frequencies. If the eardrum and bones behind the eardrum are not damaged because of the loss, a distinctive decrease in the high frequencies will be seen in the hearing test, indicating a decrease in hearing sensitivity for high frequency sounds known as a “noise-induced notch”. Damage to the eardrum and bones requires medical attention, and you will be prescribed medication and/or recommended to consult with an otolaryngologist.

NIHL and hearing aids

Hearing aids are an important tool to assist in the management of noise-induced hearing loss, because of their ability to help you hear speech sounds. A hearing aid can be programmed to resolve the loss in the high frequencies and assist the listener to hear the high-frequency sounds that may have been lost due to damage to the hearing system.

However, if it continues over some time, extensive noise exposure may have damaged cells completely. If the hair cells are not functioning due to damage, this may result in “dead areas” in the hearing system that is incapable of helping understand sound. As a result, the optimum benefits of hearing aids may not be achieved. Sometimes, an individual may be fitted with a hearing aid, to match their current hearing loss but may still be exposed to loud noise frequently. This will affect how effective the hearing aid is at helping one hear, because the hearing loss may worsen, whilst the hearing aid was programmed to fit the initial loss. It is important to continue to protect your hearing where possible, to reduce the effects of it getting worse.

How can I prevent noise-induced hearing loss?

Noise-induced hearing loss is completely preventable, and if one can understand the hazardous effects of noise and identify the sources of noise, it is possible to protect your hearing health. The unit of measurement for sound is called decibels and sounds greater than 85 dBA (A-weighted) are harmful to the hearing system. Common noises that are louder than 85dbA include power tools, motorcycle or dirt bike engines, live music concerts, an ambulance siren, and guns or rifles being fired.

4 Tips to prevent noise-induced hearing loss:

  1. Be aware and alert of noise sources that are louder than 85dbA in the environment.
  2. If you work in, or commute past, loud noise sources or engage in noisy recreational activities, be sure to use hearing protective devices such as earmuffs or earplugs.
  3. If you are unable to protect yourself from loud noise sources, move away from the source or take breaks in quieter areas.
  4. Educate family and friends about the harmful effects of noise in both occupational and recreational environments and encourage them to use hearing protection.

If you have been exposed to loud sounds, or feel like you are having difficulty hearing, it is important to get your hearing tested or to speak to a hearing expert. Take the free online Lexie hearing test and get your hearing result in 2 minutes or speak to a Lexie hearing expert for peace of mind.

Hearing library article writer and hearing expert

Written byMichaela Sewpersad

B. Audiology

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