Sounds at 85 dBA can cause hearing loss if listened to for more than 8 hours. Sounds that are louder over 85 decibels (dBa) might damage your hearing more quickly. For every 3-dB increase in noise levels above 85 dBA, the safe listening time is lowered in half. You may, for example, listen to noises at 85 dBA for up to 8 hours. At 90 dBA, you should avoid sounds for less than 1/2 hour; at 95 dBA, only 10 minutes.
The longer you expose yourself to loud noises, the more likely you are to suffer hearing loss. Hearing loss can be gradual or sudden. It can also be temporary or permanent. Some factors in determining how much noise exposure causes hearing loss include: length of exposure, intensity of the sound, frequency of the sound, whether the person wears hearing protection, and any other conditions that may lead to hearing problems such as diabetes or high blood pressure.
Exposure to loud noises can lead to hearing loss regardless of age. However, people who work with dangerous equipment, participate in activities where hearing is important, or live in areas where there is significant environmental noise are especially at risk.
Hearing loss can have many causes, but it is most commonly due to aging or disease. The two main types of hearing loss are sensory impairment and structural change to the ear. Aging can lead to sensory hearing loss, which affects the ability to hear high frequencies. This type of hearing loss starts at about 55 years old.
The louder the noise, the greater the noise level. You can listen to noises that are 70 decibels or lower for as long as you wish. At 100 dBA, you should stop listening to them after 4 minutes.
Decibels are measured with an instrument called a decibel meter. The ear is most sensitive to sounds between 130 and 140 dB. When you go into battle or use power tools, you want to avoid levels above 115 dB. Even at these high levels, however, you will not hear damage immediately caused by loud noises. That takes time: years of exposure to high levels of sound can lead to hearing loss.
Loud noises occur everywhere, in all kinds of situations. Some things that are very loud indeed include explosions, firearms shots, car accidents, and rock concerts. Other sources include roadworks, industrial plants, and machinery such as lawnmowers and leaf blowers.
Even if a noise is not extremely loud, it may still be harmful if you listen to it for a long period of time. For example, someone walking down a street might make some noise with their shoes - but if you were to do the same thing, people would call you crazy.
Sounds of 70 dBA or less are typically regarded as safe. Any sound at or above 85 dBA is more likely to cause long-term hearing impairment. Researchers discovered that those who are exposed to noise levels of 85 dBA or above over extended periods of time are at a substantially increased risk of hearing damage. Noise levels as low as 60 dBA have been linked to hearing loss.
Noise pollution is one of the most widespread environmental health concerns in both developed and developing countries. The main sources of noise pollution are traffic vehicles, aircraft, industrial plants, and weapons. Other sources include rock concerts, fireworks, and idling engines.
How does noise affect the body? Noise exposure can lead to many health problems, such as stress, sleep disorders, heart disease, cancer, and hearing loss. It has been estimated that between 10% and 20% of hospital admissions and up to 50% of occupational injuries could be attributed to noise exposure. Noise also affects animal health - for example, noise from heavy machinery can disturb wildlife and lead to conflict between workers and residents nearby. Children especially suffer from the negative effects of noise exposure because their bodies are still developing - studies have shown that listening to loud music for several hours per day can result in hearing loss by the age of 18. Also, research has shown that students who listen to music through headphones for several hours per day score lower on tests than students who do not use headphones.
The widely acknowledged criterion for minimizing hearing danger is to expose yourself to 85 decibels for a maximum of eight hours per day, followed by at least ten hours of recovery time at 70 decibels or below (at which the risk of harm to healthy ears is negligible). This should be done without damage to hearing aids or other devices used to reduce exposure to noise.
The actual threshold of hearing varies from person to person. However, the average person can detect sounds ranging from 20 dB above normal background levels up to 120 dB when listening with earphones. Sounds above this range require some kind of protection. The human ear can be damaged by loud noises; hearing loss is therefore a common side effect of many forms of occupational sound exposure.
Hearing loss can also result from prolonged exposure to lower-level sounds. This type of hearing loss is usually due to aging or disease and cannot be prevented. But it can often be reduced through the use of hearing protectors, such as headphones or earmuffs. Hearing protectors reduce the level of noise that reaches the ear by about 10 dB; thus reducing the risk of damage to hearing ability.
Finally, hearing loss may also result from environmental factors outside of our control. These include extremely loud noises such as gun shots, explosions, power tools, and motorcycles; and low-frequency sounds such as wind blowing against a wall or waves crashing on a beach.