Man and woman at a construction site, a common source of noise-induced hearing loss

The Guide on Noise-Induced Hearing Loss (NIHL)

April 14, 2021

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. This is known as noise-induced hearing loss.

What is noise-induced hearing loss?

As its name suggests, noise-induced hearing loss (NIHL) is a type of hearing loss caused when exposure to loud noise damages the sensitive structures within the ear. NIHL may be caused by exposure to loud noise for a brief period—resulting in immediate hearing loss—or it may result from exposure 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?

There are a variety of possible causes of NIHL. As mentioned, hearing loss can occur after prolonged exposure to loud noises. This could include years working in a manufacturing plant or construction site. It can also include recreational activities such as hunting or target shooting, using power tools around the house, or listening to loud music for extended periods of time—whether it be at concerts or using headphones or earbuds at unsafe volume levels. NIHL can also be caused by intense, once-off noises such as an explosion. 

Sound is measured in decibels (dBA), and sounds over 85 dBA are loud enough to cause hearing loss. That’s about as loud as the average vacuum cleaner or blender. In addition to the sound level, distance and time also factor into NIHL. For example, spending a long time very near to a sound that is too loud can greatly increase the risk of damage occurring.

What are the effects of noise-induced hearing loss?

The effects of NIHL 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 inner ear only and may worsen if continuous exposure occurs. Exposure to noise that may have caused damage to the structures in the ear will cause pain and discomfort.

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. 

In addition to hearing loss, individuals exposed to noise may also experience tinnitus—which is a ringing, buzzing, or roaring sound in the ear.

How is noise-induced hearing loss diagnosed?

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, hearing loss is generally seen across the low to the high frequencies. If the eardrum and bones behind the eardrum are not damaged, 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.

How is noise-induced hearing loss treated?

Because NIHL may be temporary or permanent, treatment options depend on the type of hearing loss experienced. NIHL is often 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. In this case, 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 noise-induced hearing loss be prevented?

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. Here are a few tips for preventing noise-induced hearing loss.

  1. Be aware and alert to noise sources that are louder than 85 decibels
  2. If you work in loud-noise environments or engage in noisy recreational activities, be sure to use hearing protective devices such as earmuffs or earplugs.
  3. If you are unable to completely 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.
  5. If you suspect you have hearing loss or believe you’re at risk of NIHL, have your hearing tested.

Test Your Hearing with Lexie Hearing

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. Lexie’s free online hearing test is clinically validated, can be taken in the comfort of your own home, and will provide you with results in only minutes. Take the test today, or contact a Lexie Expert for more information.

Image of post writer Michaela Sewpersad.

Written by Michaela Sewpersad

B. Audiology

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