Hearing loss

Q) My teenage son is in a rock band and, while I’m pleased he’s found something he’s passionate about, I’m worried about the long-term damage the loud music might be doing to his ears. I’ve suggested he wear earplugs, but he says he won’t be able to hear what he’s playing. Can you recommend any other ways to protect his hearing?—J.S., Leeds

 

A) Repeated exposure to loud noises such as gunfire, drilling or, in your son’s case, rock music is one of the most common causes of hearing loss. When noise is too loud—in general, above 85 decibels (dB), the level made by the average factory or an electric shaver—it begins to destroy the sensitive hair cells in the inner ear. These hair cells move as sound waves travel through the ear structures, and the movement is converted to nerve impulses that are interpreted by the brain as sound.

A single loud noise such as a gunshot blast can permanently harm these ear structures—and years of exposure to less intense sounds, such as loud music, can also cause irreversible damage (Pediatrics, 2001; 108: 40–3). As well as impaired hearing, such exposure to loud noise can lead to tinnitus (persistent ringing in the ear), hyperacusis (extreme oversensitivity to sound) and other hearing disorders (Int J Audiol, 2003; 42: 279–88).

Although your son isn’t keen on the idea, using ear protection is one of the best ways to prevent noise-induced hearing loss (NIHL). In a recent study of non-professional pop and rock musicians, hearing loss was minimal in those who always used ear protection and was significantly worse in those who had never used it (Ear Hear, 2006; 27: 321–30). Making your son aware of the risks of not wearing earplugs may motivate him to use them.

Fortunately, there are now hearing-protection devices designed to meet the special listening needs of musicians (Md Med J, 1998; 47: 13–8). One such device are flat attenuation earplugs, which provide an equal reduction in sound across frequencies, thus preserving the tonal balance of music and the clarity of speech. The result is that sound has the same quality as the original, only quieter.

But remember, earplugs need to be used consistently for them to be effective, so make sure they fit properly and are comfortable to wear. Etymotic Research offers a range of flat attenuation earplugs, including other custom-made products (see www.etymotic.com). 

However, there are additional ways to protect hearing. Emerging evidence shows that free-radical formation in the inner ear plays a key role in the development of noise-induced hearing loss. Antioxidants, which mop up free radicals, may be an effective intervention. Animal studies (so these results may not necessarily apply to humans) have shown that a variety of dietary antioxidants, including vitamins A, C and E, can reduce NIHL when given prior to noise exposure. A combination of high-dose vitamin A (2.1 mg/kg), C (71.4 mg/kg) and E (26 mg/kg) plus magnesium (343 mg/kg) was able to prevent NIHL, when given one hour before noise exposure and continued once a day for five days (Free Radic Biol Med, 2007; 42: 1454–63). It appears that the vitamins worked in synergy to reduce both free-radical formation and hair-cell damage, while the magnesium preserved blood flow to the inner ear, which is also affected by loud noise.

Remarkably, even antioxidants delivered up to three days after noise exposure were shown to be beneficial (Neuroscience, 2005; 134: 633–42)—although, again, these animal results may not necessarily apply to humans.

Nevertheless, there is evidence for magnesium use in humans. In a two-month, double-blind, placebo-controlled study of 300 military recruits, daily supple-mentation with 167 mg of magnesium significantly helped to protect the ear from noise-induced damage (Am J Ontolaryngol, 1994; 15: 26–32). Another Israeli study in 20 young men found similar results (Clin Otolaryngol Allied Sci, 2004; 29: 635–41).

While nutrients shouldn’t replace noise-reduction devices such as earplugs, daily supplementation with antioxidants and magnesium may add an additional level of hearing protection.

 

Protect your ears

  -           Stop smoking. A recent study of people working in noisy environments found that long-term smokers were more likely to develop permanent hearing loss than non-smokers (Clin Otolarygol, 2005; 30: 517–20).

-           Give your ears a rest. Take regular breaks from the noise source. Aim for at least a 10-minute break every hour. Also, give your ears time to recover after exposure to excessive noise. Exposure to 100 dB of sound for around two hours requires at least 16 hours of rest to avoid the hearing loss becoming permanent.

-            Consider sound conditioning. Exposure to low-level, non-damaging noise prior to high-level expos-ure can reduce NIHL (Semin Hear, 2002; 23: 13–20). So listening to not-too-loud music (at around 60 per cent of the maximum volume), for example, may be protective.

-           Have your hearing checked regularly.