Noise Induced Hearing Loss (NIHL) is a permanent hearing disorder experienced by people who have been exposed to excessive noise for either a brief time or for an extended period. Exposure to intense sounds can come from occupational or recreational activities and can result in temporary or permanent hearing loss. The important thing to note is that NIHL is preventable once the necessary precautions are taken.
To understand NIHL we need to look at how our ears and brain receive and interpret sound. When we are listening to the radio or if there is a sudden noise, sound waves travel from the outer ear canal and into the eardrum. The sound waves cause the eardrum to vibrate, which in turn causes three tiny bones in the middle ear, the ossicles, to also vibrate. The ossicles move the sound waves into the inner ear, the cochlea, which is fluid filled and home to the hair cells (sensory cells). Sound waves vibrating through the ear stimulate the top layer of the hair cells which causes them to transmit a signal to the central auditory system within the brain. Our brain interprets this signal as sound. NIHL occurs when the hair cells are overstimulated from a harmful level of noise and are consequently damaged. The damaged hair cells never heal and are never replaced leading to loss of hearing.
Understanding sound and how it is measured will increase awareness of which sounds are harmful and should be avoided. Sound is measured in decibels and we experience different levels of sound throughout our day. A whisper would only reach approximately 30 decibels while normal conversation would be 60 decibels. The noise from a motorcycle would measure at 95 decibels while a rock concert would reach 120 decibels. Any sound above 85 decibels would be considered harmful to our hearing. Exposure to intense sounds may happen when an individual is taking part in leisure activities like hunting or at a concert, or perhaps as a result from working long-term in a noisy environment such as manufacturing, the military or farming. Temporary hearing loss may only last for a few hours or days, however it’s likely that there will be long-term damage to the individual’s hearing.
If hearing loss is gradual it can take time before the sufferer is fully aware of it. Symptoms include finding it difficult to follow a conversation in a crowd or a noisy room, or having to turn up the volume on the radio in order to hear it. NIHL combined with aging can have a drastic effect on an individual’s hearing and hearing aids may be required in order to maintain a good quality of life. Another element of NIHL is tinnitus, which is a ringing or buzzing in the ear. This can be extremely distressing and uncomfortable to sufferers as they are not able to experience any quiet time. Concentration and sleep can also be affected by tinnitus, which makes normal life very difficult. If symptoms are present it is important to get an assessment by a suitable physician.
To protect yourself from NIHL it’s important to take the proper precautions when you are in a noisy environment. If possible turn off or move away from the source of the noise. If you must be in a noisy setting it’s important to wear earplugs or earmuffs to reduce the sound that reaches your inner ear. Familiarize yourself with sounds that go above 85 decibels so you can take steps to protect yourself. Always ensure that babies, children and the elderly are not exposed to loud sounds. Just a few taking the necessary precautions can reduce the possibility of long-term irreversible damage to your hearing.