What is Noise-induced hearing loss ?

Noise is part of everyday life, but at a certain level, it can become dangerous, resulting in Hearing Loss which is called Noise-induced hearing loss.

Noise-induced hearing loss (NIHL) remains a problem in developing and developed countries, despite reduced occupational noise exposure by technology.

Noise-induced hearing loss (NIHL) can harm the delicate structures and nerve fibers within the inner ear. It is typically caused by exposure to loud noises, such as those encountered during heavy engine operation, frequent gun firing by military personnel, attending rock concerts, or using personal music players at high volumes. This exposure, whether in an occupational or recreational setting, can lead to Noise-induced hearing loss (NIHL).

The effects of Noise-induced hearing loss (NIHL) can vary, with some cases resulting in permanent damage while others may be temporary. The severity and duration of noise exposure are key factors influencing the outcome. Noise-induced hearing loss (NIHL) ranks as the second most prevalent form of sensorineural hearing loss (SNHL), following presbycusis, which is associated with aging.

Exposure to loud noise can damage the delicate hair cells in the inner ear. These cells are essential for converting sound waves into electrical signals, which are then sent to the brain. Damage to these cells can impair their function, leading to hearing loss.

Noise-induced hearing loss can occur suddenly such as after a single exposure to extremely loud noise, or it can develop gradually over time after repeated exposure to loud noises. The extent of the hearing loss can vary from mild to severe and can affect one or both ears.

During testing, especially in audiograms, a notch at 4kHZ may be observed. This notch is known as an acoustic dip or a Boiler’s notch. In some cases, there may also be high-frequency hearing loss present.

Types of Noise-Induced Hearing Loss

Noise-induced hearing loss (NIHL) can be categorized into two main types based on the nature of the exposure:

1. Acoustic Trauma: 

Acoustic trauma, a type of Noise-induced hearing loss (NIHL), occurs when a person is exposed to a sudden, extremely loud noise, like an explosion, gunshot, or firecracker. The intensity of the sound is so high that it causes immediate damage to the delicate structures of the inner ear, including the hair cells responsible for detecting sound. This damage can result in immediate and severe hearing loss, often accompanied by symptoms like ringing in the ears (tinnitus) or dizziness.

2. Chronic Noise Exposure:

Chronic noise-induced hearing loss (NIHL) develops slowly over time from regular or repeated exposure to loud noises at lower levels. Industries like manufacturing, construction, or music often have high noise levels that contribute to this type of exposure. Prolonged exposure to these loud noises can gradually harm the hair cells in the inner ear, leading to a gradual decline in hearing sensitivity. Chronic NIHL usually affects both ears and is more prevalent than sudden, intense noise exposure.

     Illustrative Cases

1. Case I ( Acoustic Trauma) :

During Diwali, a 40-year-old man was lighting fireworks when one exploded near him, causing a sudden ringing sound in his ears. He promptly consulted his family ear, nose, and throat (ENT) specialist, who prescribed medication. The doctor also recommended a Pure Tone Audiometry (PTA) test, which revealed a notch at 4 kHz indicative of acoustic trauma. As a result, he now experiences permanent ringing in his ears (tinnitus) and also struggles with muffled sounds, particularly during phone calls, group discussions, or when someone speaks from a distance.

2. Case II ( Chronic noise exposure) :

A 50-year-old factory worker began experiencing a ringing sound in his ears, especially noticeable at night while sleeping. Despite working in a noisy environment, he never used hearing protection such as earplugs, noise filters, or earmuffs. He also had to raise his voice to communicate with his co-workers. Concerned, he consulted an ear, nose, and throat (ENT) specialist, who recommended a Pure Tone Audiometry (PTA) test. The test, conducted by an Audiologist, confirmed sensorineural high-frequency hearing loss (SNHL). As a result, a hearing aid was prescribed to help manage his condition.

 

Prevention of Noise-induced hearing loss (NIHL)

Preventing Noise-induced Hearing Loss (NIHL) requires a proactive approach to protect your ears from loud sounds. Here are some steps you can take:

• Avoid or Limit Exposure: 

Stay away from excessively loud environments or activities. If you can't avoid them completely, try to limit the duration of exposure.

• Use Ear Protection Devices: 

Wear earplugs, earmuffs, or noise-cancelling headphones in noisy environments. These devices can help reduce the intensity of loud sounds reaching your ears.

•  Move Away from the Source:

If you find yourself in a loud environment, try to move away from the source of the noise to reduce your exposure.

• Recognize the Symptoms:

Pay attention to any signs of hearing loss, such as difficulty hearing high-pitched sounds, muffled speech, ringing or buzzing in the ears, or a feeling of fullness or pressure in the ears.

• Consult an Audiologist:

If you experience any of these symptoms, it's important to consult with an audiologist immediately. They can assess your hearing and guide how to protect your ears in the future.

Remember, protecting your hearing is crucial for maintaining your overall health and quality of life.