October 9, 2014

Noise Induced Hearing Loss

Loud Noise and Hearing Loss

Roughly 10 million cases of hearing loss can be attributed to noise exposure. Noise induced hearing loss (NIHL) is characterized by a gradual, progressive loss of high frequency hearing sensitivity that usually presents as a “notch” that occurs at or around 4000 Hz.

NIHL can occur from a one-time exposure to loud noises or from extended exposure to harmful levels of sound. Sound levels are measured in decibels (dB). Normal conversations typically occur between 50-60 dB SPL, which is not loud enough to cause damage to your hearing. Exposure to sound levels 85 dB and higher over an extended period of time can cause permanent damage to your hearing. The softer the sound, the longer period of time it is safe to listen to the sound. The graphic below, created by the Dangerous Decibels public health campaign, outlines guidelines based on NIOSH and CDC recommendations for maximum time exposure allowed in various levels of sound.

Ways To Protect Your Hearing

There are many ways to prevent NIHL, such as:

  • Avoid or limit exposure to dangerously loud sounds
  • Decrease the volume of music systems
  • Move away from loud sound sources when possible
  • If you must be around loud sounds, use appropriate hearing protection.

Hearing Protection Devices

At The Hearing Center, we offer a variety of hearing protection devices. Common devices include:

  • Swim plugs are designed to prevent moisture from entering the ear canal during swimming, showering and water sports
  • Shooter’s protection is designed to protect hunters/shooters from impulse noises up to 160 dB peak SPL. These devices can be made with special acoustic filters that allow for awareness of conversation and the ability to track animals.
  • Industrial noise protection- Some work places require workers to wear custom hearing protection due to exposure to dangerous sound levels. Employees who work in industrial factories, construction sites and around aircraft equipment are likely to be required to wear hearing protection. Specialized devices can be made that can connect to radios for those who work in jobs that require radio use.
  • Musician earpieces provide hearing protection for musicians who practice and perform in a variety of settings. Depending on the source and location of the sound, different levels of attenuators can be used in the earpieces to allow for optimal hearing protection.
  • Motorcyclist’s protection is designed to help eliminate wind noise under a helmet.
  • Custom sleep plugs can be used to promote interrupted sleep.
  • Custom fit ear tips for mp3 players or other headphones are designed to have standard earphones fit into a custom fit ear tip. These earplugs help block excessive environmental noise and allow the listener to turn down the music volume.

How Much Hearing Protection Is Enough?

Custom hearing protection is rated by a system known as the Noise Reduction Rating (NRR). The NRR is used to determine the ability of hearing protection devices to decrease sound exposure within an environment. The higher the NRR number assigned to the hearing protection, the greater potential for noise reduction. It is important to remember that the NRR number is not simply subtracted from the loudness of sound. To compute how much hearing protection is provided by an earplug, take the NRR number (in dB), subtract 7, and then divide by 2. If an earplug has a NRR of 29 dB, the equation would be (29-7)/2=11. This mean if you were at a concert were the level of noise exposure was 100 dB and your hearing protection had a NRR of 29 dB, your actual noise exposure level would be 89 dB. If you are wearing hearing protection in combination, you do not add the NRR of both devices together to find the amount of protection. Instead, you would add 5 dB to the higher NRR to find the combined hearing protection. For example, if you were wearing earplugs with an NRR of 17 dB and earmuffs with a NRR of 24 dB, your combined NRR would be 29 dB.

If you believe you are at risk for noise induced hearing loss, make an appointment with your JHBI audiologist to discuss a custom hearing protection option that is suitable for your needs!


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