Noise and Your Hearing Can noise damage your hearing?
Every day we experience sounds in our environment such as the television, radio, washing machine, cars, music, and trucks. When you are exposed to harmful sounds, such as sounds that are too loud or loud sounds over a long time, the sensitive structures of the inner ear can be damaged, causing a hearing loss. Noise-induced hearing loss (NIHL) is the diminished hearing ability that occurs as a result of the damage to the inner ear by these harmful sounds. The noise damages the hearing cells of the hearing organ (cochlea) in the inner ear. How much noise is too much? Both the loudness of sound (called the intensity) and the amount of time you hear the noise will determine your risk of hearing damage. The loudness of sound is measured in decibels (dB). The hearing cells in your inner ear can tolerate no more than 85dB of sound for 8 hours before permanent damage starts to occur. At higher sound levels, you could lose hearing in even less time, because every 3dB increase in sound halves the amount of time the ear can tolerate sound before damage occurs. Sounds of 100dB can cause damage in just over 15 minutes and sounds of 103dB in just 7 minutes 30 seconds! The table below provides a guideline of the sound level in dB which is measured for some typical listening environments. For example, if you are riding a motorcycle, you receive an average loudness of 95dB, which means that if you ride an unsilenced motorcycle without hearing protection for over one hour, you risk noise damage. Keep in mind that the hair cells can also be permanently damaged from a sudden or one-off exposure of 130-140dB or above. This might occur from gunfire close to the ear or a blast injury. This kind of sudden damage is called acoustic trauma. The following table shows the safe limits for common noises: Level in decibels (dB) | Noise | Exposure time | 140 - 150 | Firecracker, gunshot, jet engine | No safe exposure at this level. Acoustic trauma may occur. | 120 - 130 | Ambulance siren, car horn | Less than 7 seconds of exposure. Risk of acoustic trauma starts at this level. | 110 | Rock concert, nightclub | Levels can range from 95-130dB, but concerts are often at 110dB, depending on distance from the speakers. At this level, exposure of more than 1 minute risks permanent hearing loss. | 105 | Personal stereo at maximum volume, amplified rock music | Levels can range from 105-130dB. At these levels it is less than 2 minutes before damage begins to occur. | 100 | Chainsaw, Jackhammer, Wood-working area | No more than 15 minutes unprotected exposure recommended. | 95 | Motorcyle | Unprotected exposure for over 1 hour could result in noise damage. | 90 | Lawn mower, workshop tools | Exposure for longer than 2 hours and damage may occur if no hearing protection is worn. | 85 | Heavy city traffic, average factory | Prolonged exposure of over 8hrs a day can cause gradual hearing loss. | 70 | Vacuum cleaner, noisy restaurant | Considered within safe limits for prolonged exposure of over 16 hours a day. | 60 | Normal conversation | Considered within safe limits. | 40 | Refrigerator humming | Considered within safe limits. | 30 | Whispered voice | Considered within safe limits. |
In 2005, researchers from the Ear Science Institute Australia (ESIA) and Ear Sciences Centre at The University of Western Australia, measured sound levels in twelve popular entertainment venues in Perth, Western Australia. To review the findings, Click Below
How common is noise induced hearing loss? Noise induced hearing loss is the second most common type of hearing loss after presbyacusis (old age associated hearing loss), and all age groups can be affected. There is a slight male bias, but it is still unknown if this is a result of occupational status (such as working with heavy machinery) or an increased vulnerability to NIHL. Studies show that deafness from noise exposure at work (often termed industrial deafness) is a serious community problem. For example, a study of the farming industry in Australia indicated that over two-thirds of farmers had hearing loss attributable to noise exposure. Researchers are now predicting an increase in recreational noise induced hearing loss with the increase in use of personal stereos at excessively amplified levels. How can I tell if noise has damaged my hearing? Noise damage can be temporary or permanent, and you may not recognise damage to your hearing immediately. Temporary hearing loss is recognised as a change in your hearing after a few hours in a loud environment, such as a concert. Typically this is a dullness in hearing that recovers over time and is termed temporary threshold shift. You are also likely to notice tinnitus (ringing in the ears) immediately after the noise exposure. Temporary damage occurs due to fatigue of the hair cells. If the hair cells recover, then the damage was deemed temporary. If the sound exposure was excessive then the cells don't recover and permanent noise damage results. Permanent threshold shift is often not detected until 48 hours after the exposure and can become increasingly worse for a number of years after the original damage occurred. Typical symptoms reported by those with a hearing loss is that sounds become distorted or muffled, and that it is difficult to understand speech on the telephone, television or in situations with background noise. Aside from the loss of hearing acuity, permanent noise damage can also result in permanent tinnitus, which can be distressing and reduce your overall quality of life. Keep in mind that noise-induced hearing loss is often gradual, and that you may only lose your ability to hear high-pitched sounds at first. If you have any concerns that you may have noise induced hearing loss, you should have a comprehensive hearing test with an audiologist. What can I do to protect my hearing? Hearing loss from noise exposure is preventable. All individuals should understand the hazards of noise and know how to protect their ears: - Be familiar with the kinds of activities that could damage your hearing and the maximum amount of time you can be exposed to these activities before permanent damage occurs.
How much noise is too much? - Avoid or modify those situations where noise is at dangerous levels. For example, don't stand too close to the speakers at concerts, don't stand in the vicinity of people using noisy machinery, spend less time in noisier environments, turn down your iPod or personal stereo or consider purchasing quieter machines in a noisy workplace. For more information on noise control measures, particularly in the workplace, Click Link.
Noise control measures - If there are no alternatives to reducing the noise level in your environment, wear earplugs or other hearing protective devices when involved in a loud activity. For more information on earplugs and earmuffs, Click Link.
Earplugs and earmuffs - Have a hearing test by an audiologist, who is a health professional trained to identify and measure hearing loss and to rehabilitate persons with hearing impairments.
Audiologists and their role
What can I do if I already have noise damage? Damage to the hair cells of the inner ear is irreversible, so permanent noise induced hearing loss will not improve on its own. Listening devices such as hearing aids will help to increase the volume of those sounds that you have problems hearing, but they will not improve your permanent hearing levels. Remember that if you already suffer from a degree of hearing loss it is imperative that you protect your residual hearing by following the noise protection guidelines above. The information contained on this page is not meant to be a substitute for the advice from a surgeon or other clinical specialist. This is not a complete discussion of ear disease and is not a complete explanation of the risks of surgery and/or treatments. |
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