People participating in a variety of activities need ear protection. The NIDCD (National Institute on Deafness and Other Communication Disorders) estimates that 15 percent of Americans between ages 20 and 69 have hearing loss caused by loud noises (NIDCD, 2014). Ear protection prevents this hearing loss. Additionally, ear protection keeps water out of the ear canal during water sports. Ear protection is important because ear damage is preventable, and once damage occurs it may be irreversible.
Loud Noise Damages Hearing
Sound waves enter the outer ear and travel to the eardrum, causing the eardrum to vibrate. Small bones transfer vibrations to the cochlea. The vibrations in the cochlea are detected by specialized hair cells. The hair cells transmit information via the auditory nerve to the brain. Hair cells are fragile and can be damaged by loud noise. Hair cells in humans cannot regenerate, making hearing loss irreparable and irreversible.
The process of hair cell damage from noise exposure can be slow and progressive, or it can happen quickly after exposure to a loud noise. Understanding which noises pose a risk to hearing helps individuals select appropriate ear protection.
Sound is measured in units called decibels (dB). Sounds measuring less than 75 dB do not pose a risk to hearing, whereas sounds at or above 85 dB cause hearing loss. Normal conversations measure 60 dB, whereas a power mower measures 90 dB. A sound at 100 dB damages hearing within 15 minutes. Concert speakers generate sounds as high as 110 dB, damaging hearing within one minute. Similarly, stereo headphones can be as loud as 105 dB, damaging hearing within minutes. Discharges from firearms and explosions from firecrackers near 150 dB; thus ear protection is required.
Types of Ear Protection for Noise Reduction
In the United States, ear protection carries a noise reduction rating (NRR), indicating the decibel reduction provided. Wearing two types of hearing protection, such as earplugs and earmuffs, does not offer an additive advantage and only provides a few more decibels reduction than the higher NRR value.
Earplugs are available in foam, silicone, flanged, and custom molded styles. Foam earplugs are compressed and placed in the ear canal. These earplugs are used in manufacturing and construction, providing NRR values from 20 to 35 dB. Silicone earplugs are moldable, covering the external ear canal, providing NRR values from 20 to 25 dB. Flanged earplugs provide less sound distortion and have variable NRR, often around 20 dB. Some flanged earplugs offer a cap, allowing the user to hear without removing the earplugs. Custom molded earplugs may be vented for communication, may have filters allowing less sound distortion, or may contain electronics to block loud sounds and amplify soft sounds.
Earmuffs, which fit over the external ear, are used for a variety of activities including shooting and construction. Earmuffs are available with a range of NRR. Advantages of earmuffs include comfort and the ability to wear hearing aids. Disadvantages of earmuffs include bulk and difficulty getting a proper seal around hair and eyeglasses. Earmuffs passively block damaging sound waves. Electronic earmuffs have circuits that allow amplification of sound in addition to protection against loud sounds. Earmuffs can also be purchased with built-in speakers to play music.
Although some forms of hearing protection play music, headphones available with music players are not ear protection. Frequent exposure to sounds exceeding 85 dB causes long-term hearing loss. Many people listen to music players at higher levels.
Water Sports Damage Ears
Water sports pose risks for different types of ear damage; all types of ear damage can cause hearing loss. Surfer’s ear, caused by repeated exposure to cold water and wind, causes bony growths in the ear canal. Swimmer’s ear is an outer ear infection resulting from water exposure. Water can cause infection in people with exposed middle ears due to eardrum perforation or tube placement.
Different types of ear protection are available for water sports. Surfers need protection to keep the ear warm and dry. Swimmers who have had ear infections use earplugs to keep water out, as do people with exposed middle ears. Chisholm, Kuchai, and McPartlin (2004) found that petroleum jelly and a cotton ball kept the ear as dry as commercially available earplugs.
Effectiveness of Ear Protection
Some hearing loss caused by damage from water sports is irreversible and all hearing noise—induced hearing loss is irreversible, highlighting the importance of ear protection. With proper ear protection, hearing loss is preventable.
Lisa A. Rabe
See also: Age-Related Hearing Loss; Cochlea; Deafness; Sensory Receptors; Tinnitus
Chisholm, Edward J., R. Kuchai, & D. McPartlin. (2004). An objective evaluation of the waterproofing qualities, ease of insertion and comfort of commonly available earplugs. Clinical Otolaryngology and Allied Sciences, 29(2), 128—132. http://dx.doi.org/10.1111/j.1365-2273.2004.00795.x. PMID 15113295
National Institute on Deafness and Other Communication Disorders. (2014). NIDCD fact sheet: Noise-induced hearing loss (NIH Pub. No. 14-4233). Retrieved from http://www.nidcd.nih.gov/staticresources/health/hearing/NIDCD-Noise-Induced-Hearing-Loss.pdf