Sound Levels and Hearing Loss

The World Health Organization (WHO) recently released a report on the effect of unsafe listening practices on hearing. They estimate that up to one billion young people worldwide could be at risk of hearing loss due to exposure to excessive sound levels.  According to WHO, teenagers and young adults in middle- and high-income countries are at particular risk due to: 

• Nearly half being exposed to unsafe levels of sound from the use of personal audio devices.
  
• Around 40% being exposed to potentially damaging sound levels at clubs, discotheques and bars.

An estimated 5.2 million children and adolescents aged 6–19 years have suffered permanent damage to their hearing from unsafe levels of sound.  The fact that people are losing their hearing at much younger ages than they did just 30 years ago, along with the surge in sales of personal listening devices, suggests that loud music may be playing a role.
 
How does loud music affect the ears? Exposure to loud music, whether live or recorded, can damage sensitive structures in the inner ear, resulting in noise-induced hearing loss (NIHL).  Once damaged, the sensitive structures, called hair cells, cannot repair themselves. NIHL is related both to the decibel level of a sound and how long someone is exposed to it.  Additionally, the risk of developing NIHL from exposure to loud sounds is cumulative, adding up over a lifetime of exposure.

At what sound level can damage to the ears occur? Sound level (or more correctly sound pressure) is measured in decibels (dB).  The lower limit of hearing is defined as 0 dB and a normal conservational level is around 60 dB.  Sound reaching 85 dB or stronger, particularly if the exposure is prolonged, can result in permanent hearing damage. Many personal listening devices generate sound levels as high as 105 dB at maximum level, more than enough to cause permanent hearing loss.

 What about the effects of prolonged listening?  As mentioned, it’s not just the sound level that is a concern regarding potential hearing damage. The length of exposure is also a critical issue. Hearing damage can occur with as little of 15 minutes of exposure to music at 100 decibels. With newer digital music players being capable of storing several hours of music, prolonged listening times increase listener’s risk of cumulative damage to their ears.

What can be done to minimize the risk of hearing loss?  Fortunately, NIHL related to listening to loud music, whether live or recorded, is almost completely preventable. Here are some tips for minimizing the risk of developing NIHL from loud music:

1. Follow the 60 percent/60 minute rule.  Researchers have determined that listening to music, a movie, or a video game a portable music player at 60 percent of its potential volume for one hour a day is relatively safe. This 60 percent for 60 minutes rule is a good guideline for everyone to follow.
    
2. If noise levels reach the point that you have to raise your voice to be heard more than an arms length away, remove yourself from the situation or wear earplugs.
    
3. In situations in which live music is consistently louder than 85 dB, consider the use of sound attenuating ear plugs. If inserted properly, earplugs can reduce the exposure by 5 to 45 dB, depending on the type of earplugs. The ones used by professional musicians can be quite expensive, however, “consumer” models are available for as little as $12 (e.g.  ETY•Plugs® High Fidelity Earplugs).
    
4. Certain newer listening devices (e.g. iPod Shuffle) allow the listener to limit the maximum volume of the device.
    
5. Consider using noise-canceling earphone or ear buds.  These allow the listener to reduce the volume of the music by blocking the majority of external sounds.
    
6. Take listening breaks.  When going to nightclubs, sporting events or other noisy places, move to a quieter spot intermittently to help reduce the overall duration of noise exposure.

You know that you have abused your ears if you have ringing in the ears, a feeling of fullness in the ears, or if speech sounds muffled.  Avoid loud noises long enough to allow your hearing to return to normal. After that, avoid repeating the exposure to excessive loud sound.  If features suggestive of damage to the ears persist, have your hearing checked by a medical professional.
 
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