What is Noise Exposure and Hearing Loss?
As the world becomes more industrialized, being exposed to noise is turning into a major risk at work and a significant source of pollution in the environment. Concerns about noise and hearing loss have been increasing over the last hundred years. Due to growing populations, more industries, the growing use of motor vehicles, and a lot of recreational activities, noise pollution is getting worse all over the world. Noise can cause both hearing and overall health problems because of the immediate harmful effect of very loud sounds and the long-term harmful effects from being exposed to noise over time.
Many people are not aware of the negative effects of noise on their physical and mental health. Government agencies like the United States Occupational Safety and Health Administration (OSHA) have the job of preventing exposure to noise and making employers, employees, and the general public more aware of how being exposed to noise can impact them. Research is also being done in different places with a lot of noise, like factories, military bases, and airports, to understand how big of a problem noise exposure is for the public.
What Causes Noise Exposure and Hearing Loss?
Exposure to loud noise can happen in either a work or everyday setting. Work-related noise exposure could happen in areas like mines, factories, rail yards, construction sites, or military bases. Everyday noise exposure can be experienced on highways, trains, airplanes, and in recreational places like nightclubs, sporting venues, or shooting ranges. Another source of noise exposure that’s becoming more common, especially in younger adults, is using headphones or earphones to listen to loud music, which can lead to hearing loss at an earlier age.
Noise-induced hearing loss could be either acute or chronic. Acute exposure to loud noises, like explosions or loud music, can cause sudden, or ‘acute’, hearing loss, which might be temporary or permanent, depending on how loud the noise was. On the other hand, being exposed to loud noise over a long period of time can cause a more gradual, or ‘chronic’, hearing loss along with some other health issues.
Several factors can influence the extent of noise-induced hearing loss. These include socioeconomic status, ethnicity, age, tobacco use, exposure to drugs that can harm the ear, and related health conditions such as diabetes and high blood pressure.
Risk Factors and Frequency for Noise Exposure and Hearing Loss
Noise-Induced Hearing Loss (NIHL) is a condition which is hard to track due to limited data. However, the World Health Organization believes that over 1 billion young people around the globe, aged between 12 and 35, risk developing hearing loss because of exposure to loud sounds during their leisure time. More often, men are affected by NIHL – a fact attributed to the higher exposure in certain jobs, especially amongst those of lower socioeconomic status. Women, on the other hand, may be partially shielded from NIHL due to the effects of hormones. In the employment space, NIHL comes in second as the most frequent occupational disease, with an estimated one in five adults in the U.S suffering hearing loss due to it.
Signs and Symptoms of Noise Exposure and Hearing Loss
Exposure to a single loud noise can lead to a condition known as acoustic trauma. This condition includes symptoms such as:
- Hearing loss
- Ringing in the ears (tinnitus)
- Increased sensitivity to sound (hyperacusis)
- Dizziness
- Feeling of fullness in the ear
- Headache
In addition to these symptoms, individuals may also experience an event called acoustic shock, with additional symptoms such as ear pain, nausea, anxiety, fatigue, and depression. On the other hand, continuous exposure to loud noise generally leads to symptoms like hearing loss and ringing in the ears.
Ringing in the ears, known as tinnitus, is a symptom often bothers people. It’s an early sign of ear damage and typically shows up when an audiogram detects hearing loss in the 3 to 6 kHz range.
Loud noise exposure can have other non-auditory effects like causing headaches, anxiety, depression, sleep disturbances, difficulty focusing with daytime drowsiness, an increased risk of high blood pressure and heart disease in adults, and cognitive decline in children. It is important to note that hearing loss caused by loud noise generally affects the 3 to 6 kHz range and is most noticeable in normal sounds heard above 8 kHz.
Diagnosing noise-induced hearing loss (NIHL) typically involves considering three factors: the type and amount of noise exposure, the potential age-related hearing loss, and possible degenerative changes in predisposed individuals.
NIHL affects the nerves of hearing and is usually bilateral (affecting both ears) with similar loss on both sides—unless caused by noise exposure on one side, such as from firearm use. In such cases, one ear exposed to the weapon’s muzzle may be more affected while the other ear is pointed away. It’s important to note that patients with typical NIHL often have normal or near-normal ability to understand speech.
The development of NIHL due to chronic noise exposure is fastest during the first 10 to 15 years of exposure, after which the loss rate decreases gradually without much progression. Generally, noise exposure alone doesn’t cause hearing loss of more than 75 dB in higher frequencies and 40 dB in lower frequencies. Patients with NIHL show a specific pattern—a dip or “notch”—at 3000, 4000, or 6000 Hz in a hearing test or audiogram, with recovery at 8000 Hz.
Testing for Noise Exposure and Hearing Loss
If you’re being tested for Noise-Induced Hearing Loss (NIHL), it’s important to know that a diagnosis is only made after thoroughly checking for all other potential causes of hearing loss. This is especially important for those who have job-related NIHL, as they may be entitled to compensation. Various specialized hearing tests are used to confirm a diagnosis of NIHL.
One such test is ‘Pure-tone Audiometry’. This standard hearing test often shows that those with NIHL have a hearing loss in both ears, more for high-pitch sounds, with a dip in hearing between the frequencies of 3 and 6 kHz, and better hearing at 8 kHz. In cases where hearing loss is not the same in both ears, a magnetic resonance imaging (MRI) test of the brain is done to rule out a tumor known as a vestibular schwannoma.
‘Hearing in Noise Test’ is another test where sentences are repeated in a quiet environment and with background noise. This test helps to identify people suffering from age-related hearing loss and central auditory processing disorder who might face difficulty hearing in noise. The results of this test help in setting up hearing aids correctly.
‘Speech Audiometry’ is a hearing test that assesses how well a person can hear, understand and recognize speech. It determines the quietest level that speech can be heard and understood half of the time (known as the speech recognition threshold) as well as how many words are repeated correctly from a list (termed as the word or speech discrimination score).
The ‘Otoacoustic Emissions’ test measures sounds produced by the inner ear in response to a sound presented to the ear – it’s an easy-to-use, highly sensitive, and objective test. The ‘Brainstem-evoked Response Audiometry’ test measures the electrical activity of the hearing nerve and the brain pathways that carry sound. Both tests are effective in detecting early NIHL and identifying cases of faked hearing loss.
The value of some investigations, like ‘auditory reflex testing’ and ‘high-frequency audiometry’, that might help find early signs of NIHL, is still being evaluated by researchers.
If you’ve been diagnosed with NIHL, it’s important to calculate the extent of your hearing loss to assess any potential compensation claims. This calculation involves three steps: getting the average of hearing thresholds of each ear at certain set frequencies to find the average hearing ability, working out the hearing handicap for each ear based on subtracting a standard value from the average and then scaling that result, and then assessing the total hearing handicap by taking a certain sum of better and worse ear hearing handicaps.
Treatment Options for Noise Exposure and Hearing Loss
The best way to treat Noise-Induced Hearing Loss (NIHL), which happens when the ears are exposed to loud sounds, is by using hearing aids. Doctors usually recommend a hearing aid when the Speech Reception Threshold (SRT) – that’s the quietest level at which a person can hear speech – is more than 25 decibels, or the person’s understanding of words is less than 80% when sounds are 50 decibels above their hearing threshold. If a person has tinnitus (a buzzing or ringing sound in the ears) caused by noise, it can be managed with a device called a tinnitus masker, or through tinnitus retraining therapy.
Research has shown some medicines to be promising in protecting against NIHL. These include corticosteroids, which are medications that reduce inflammation. Antioxidants and neurotrophins, which are proteins that help nerve cells grow and function, may also be beneficial. Corticosteroids can be powerful in treating sudden sound-based injuries with their anti-inflammatory effect, whether given through an IV, orally, or directly into the ear. Yet, their effectiveness in treating NIHL caused from long-term workplace noise exposure isn’t fully understood.
Using hyperbaric oxygen therapy – where you breathe pure oxygen in a pressurized room or tube – has also been beneficial for sound-based injuries, especially when corticosteroid treatment doesn’t work. Certain antioxidants, like N-acetyl cysteine, D-methionine, and coenzyme Q10 are currently being tested as potential protective measures against NIHL. Magnesium and vitamins A, E, C, and B12 have also shown positive effects in protecting against NIHL in animal studies.
In all cases, the best way to manage NIHL is to prevent it from occurring in the first place. This includes monitoring noise levels regularly, reducing noise exposure at work, and catching any damage to hearing caused by noise early. Noise monitoring can be done by taking measurements of the sound levels in specific areas or by having individuals wear a device that measures their personal exposure to noise.
We can lower the exposure to noise at work by using engineering controls (like putting up enclosures around noise sources), administrative controls (rules that regulate noise exposure), and by using personal hearing protection like ear plugs and ear muffs.
Keep in mind that early identification of damage to hearing from noise can be done through regular hearing tests and education on the health risks of noise. All employees working in noisy environments should have a hearing test within six months of starting work. If these tests reveal a hearing shift that increases by 10 decibels or more at certain frequencies, then the worker should join a hearing conservation program.
What else can Noise Exposure and Hearing Loss be?
When it comes to diagnosing Noise-induced hearing loss (NIHL), several conditions need to be considered as they can cause related symptoms. These include:
- Presbycusis: this is hearing loss related to advancing age and often comes with reduced high-frequency hearing. This condition could be due to the damage of hair cells in the ear or reduced functioning of the area supplying blood to the inner ear.
- Genetic hearing loss: This typically starts in childhood or early teenage years and gets worse over time. There can also be other structural abnormalities present in the ear.
- Hearing loss from past infections: Conditions like labyrinthitis, meningitis, or encephalitis could cause damage leading to hearing loss similar to NIHL.
- Hearing loss from brain issue: Issues with the body’s central nervous system, such as a stroke or tumors in certain areas of the brain could lead to hearing loss. The hearing loss usually starts suddenly and may occur together with other neurological issues.
- Auditory neuropathy and synaptopathy: These are conditions that lead to problems in how auditory signals are processed. These may occur due to issues with the hair cells inside the ear, the auditory nerve, or the connection between these two. People with these conditions often report having trouble hearing in noisy environments and suffer from hearing loss in both ears.
- Feigned hearing loss: This is when a person pretends to have hearing loss. The person may so much emphasize hearing difficulties but would go on to maintain normal speech volume. A hearing test might reveal this condition.
Having an awareness of these conditions can help to properly diagnose NIHL. The goal is to identify the real cause of the hearing loss so as to know the best way to manage it.
What to expect with Noise Exposure and Hearing Loss
According to studies, Noise-Induced Hearing Loss (NIHL) typically worsens significantly within the first 10 to 15 years, after which the degree of hearing loss tends to balance out a little. Essentially, once the exposure to loud noise is stopped, NIHL does not typically deteriorate further.
Since NIHL is a permanent and irreversible condition, prevention is very important. It’s crucial to control the noise exposure by adhering to safety limits. In terms of working environment guidelines, OSHA (the U.S Occupational Safety and Health Administration) specifies that during an 8-hour workday, employers must implement noise-management solutions if noise levels exceed 90 dB. If noise levels are more than 85 dB, employers need to introduce preventive measures, such as providing hearing protection and conducting annual hearing tests. If the duration of noise exposure varies from 8 hours, the allowed limit increases or decreases by 5 dB when the duration of exposure is cut in half or doubled.
In a similar vein, the U.S National Institute for Occupational Safety and Health recommends that the maximum workplace noise exposure should average at 85 dB over an 8-hour day. If the duration of exposure isn’t 8 hours, the permissible limit goes up or down by 3 dB when the exposure duration is cut in half or doubled. For instance, for a 4-hour workday, the limit would be 88 dB, and for a 16-hour workday, it’d be 82 dB.
The World Health Organization also proposes daily noise exposure limits, stating that noise levels should not surpass 70 dB over a 24 hour period or 85 dB over a 1 hour period to prevent hearing damage.
Possible Complications When Diagnosed with Noise Exposure and Hearing Loss
Being persistently exposed to loud noises can have harmful effects on not only your ears but also your general health and social life. It is widely understood that loud noise can cause hearing loss, ringing in the ears, and dizziness. However, it also impacts the body’s chemical balance, raising levels of specific hormones such as cortisol and norepinephrine. These hormonal imbalances can significantly heighten the risk for high blood pressure, heart diseases, heart attacks, and strokes.
Regularly being in a noisy environment can affect sleep quality, making workplace accidents more likely. It’s also noted that chronic noise exposure can lead to increased chances of experiencing depression and anxiety disorders. Excessive noise can disrupt family life, leading to issues like irritability, frustration, confusion, and difficulty in concentration.
Noise-Induced Hearing Loss (NIHL) also has a social impact as it can affect one’s communication skills. This can lead to a decreased sense of self-esteem and even cause problems in relationships. Moreover, it can decrease attention span and cognition, which could potentially increase the risk of dementia. Loud noise can also affect job performance, but this largely depends on each person’s resistance to noise. From an economic perspective, the costs that employers have to bear for hearing loss compensation can be quite high.
Effects of Loud Noise Exposure:
- Hearing loss, ringing in the ears, and dizziness
- Increased hormone levels leading to higher risk of high blood pressure, heart diseases, heart attacks, and strokes
- Poor sleep quality and increased risk of workplace accidents
- Increase in depression and anxiety disorders
- Disruption in family life leading to frustration, confusion, and reduced concentration
- Decreased sense of self-esteem and relationship issues
- Reduction in attention span, cognition, and possible increase in dementia risk
- Potential impact on work performance
- High compensation cost for employers due to hearing loss
Preventing Noise Exposure and Hearing Loss
The World Health Organization notes that hearing loss is one of the top 20 reasons for disease-related issues and is the most common disability worldwide. Noise-Induced Hearing Loss (NIHL), which can be caused by loud noise, is the easiest form of hearing loss to prevent. At the heart of prevention efforts is education for everyone. Both employees and their employers need to understand that hearing can only be protected if efforts are made to lessse reduce exposure to harmful noise, not just in the workplace but anywhere it may occur.
Regular screening for hearing loss, using hearing protection devices such as earplugs, and receiving proper training are important components of hearing protection programs. The public must also be aware of the harmful effects of noise and know what noise levels are safe, particularly in social gatherings, on roads, and at music concerts. Adhering to regulations at all levels is crucial to avoid the damaging effects of noise exposure.
