ARE you missing nuances in conversations more often these days? Do you frequently ask people to repeat what they’ve just said? Do you keep turning up the volume on your TV or radio?
If so, you may be developing presbyacusis. It is the medical term for age-related hearing loss, and US scientists say it makes you more likely to develop thinking and memory problems, compared to other older adults whose hearing is normal.
The latest and long-term study, by researchers at John Hopkins University School of Medicine, is believed to be the first to gauge the impact of hearing loss on higher brain functions over the long term.
There is no single cause of age-related hearing loss, say hearing specialists. Along with the passing of the years, some drugs, head injuries and too much noise can all cause lasting damage to hearing, they say. However, excessive noise exposure has been identified as a major risk factor.
Research shows that about 80% of deafness is caused by damage to the tiny hair cells in the inner ear. Hearing is yet another case where prevention is better than cure — because there is no cure. Experts will tell you that fish, amphibians and birds are able to regenerate these cells. In humans, damage to hearing is permanent.
An aggravating factor in hearing loss is that many people who need a hearing aid don’t get one for a variety of reasons, say researchers. This can exacerbate the effects of the hearing loss on brain function, they say.
Senior study investigator Dr Frank Lin, an otologist and epidemiologist at Johns Hopkins Hospital, says hearing loss should not be looked on as an inconsequential part of ageing, because the research results show it may come with some serious long-term consequences for a healthy brain.
On average, older adults with hearing loss are shown to develop a significant impairment in their cognitive abilities a little over three years sooner than those with normal hearing, Dr Lin says.
The findings, reported online in the Journal of the American Medical Association Internal Medicine in January, are among the first to emerge from a large, ongoing study monitoring the health of 1,984 black and white men and women between the ages of 75 and 84.
All study participants were in good general physical health and had normal brain function when the study began.
Factors already known to contribute to loss of brain function were accounted for in the researchers’ analysis, including age, high blood pressure, diabetes and stroke.
Participants were initially tested for hearing loss, which hearing specialists define as recognising only those sounds louder than 25 decibels.
"Our findings emphasise just how important it is for physicians to discuss hearing with their patients and to be proactive in addressing any hearing declines over time," says Dr Lin.
When it comes to possible explanations for the cognitive slide that can accompany hearing loss, Dr Lin says research points to links between hearing loss and social isolation, with loneliness being well established as a risk factor for cognitive decline.
Degraded hearing may also force the brain to devote too much of its energy to processing sound, and at the expense of energy spent on memory and thinking. He adds there may also be some common, underlying damage that leads to both hearing and cognitive problems.
Dr Lin and his team have plans under way to launch a larger study to determine if the use of hearing aids or other devices to treat hearing loss in older adults might forestall or delay cognitive decline.
He estimates that in the US, as many as 27-million Americans over age 50, including two-thirds of men and women aged 70s and older, suffer from some form of hearing loss. More worrying, he says, is that only 15% of those who need a hearing aid get one, leaving much of the problem and its consequences untreated.
There are no definitive statistics of the incidence of hearing problems among South Africans over the age of 50, but rates are likely to be proportionately as high, say experts.
While reactions to encroaching hearing loss differ from person to person, the South African Hearing Institute, on its website, says most impaired people suffer some social, psychological and physical problems as a result of their hearing. People who have hearing loss will benefit socially and psychologically, and improve their quality of life when their hearing loss is treated with proper hearing instruments, the institute says.
Causes of hearing loss
Ageing, some drugs and head injuries can all cause lasting damage to hearing, according to the South African Hearing Institute.
However, the most common type of permanent hearing loss results from excessive noise exposure, because frequent exposure to loud or moderately loud noise over a long period of time can damage the soft tissue of the inner ear, the institute says on its website.
How it happens
Cells and nerves in the inner ear are destroyed by continuous or repeated exposure to loud sounds. If enough cells and nerves are destroyed, hearing is permanently damaged.
Whether noise harms your hearing depends on the loudness, the pitch and the length of time you are exposed to the noise, the Institute says.
The loudness of a sound (measured in decibels, or dB) and the length of exposure are related. The louder the sound, the shorter the exposure can be before damage occurs." For example, the institute says that eight hours of exposure to 85 dB noise on a daily basis can begin to damage your ears over time.
Using power tools (at about 100 dB), listening to loud stereo headsets (at about 110 dB), attending a rock concert (at about l20 dB) or hearing a gunshot (at 140 dB to 170 dB) may damage the hearing of some people after only a few times.
10 top tips to protect your hearing
Keeping your hearing healthy is largely about knowing how much loud sound you are exposed to, say hearing specialists.
A "noise diet" can protect your hearing from future problems, they say.
Here are some tips:
1. Use earplugs. The louder the noise and the longer you’re exposed to it, the greater the chance of damaging your hearing. Protect your ears with ear protectors – earplugs or earmuffs – and get away from the noise as quickly or as often as you can.
2. Turn down your iPod. Don’t listen to your personal music player at very high volumes, and never to drown out background noise. If the music is uncomfortable for you to listen to, or you can’t hear external sounds when you’ve got your headphones on, then it is too loud.
3. Be smart. If your iPod has a "smart volume" feature, use it. It will help you regulate the volume.
4. Wear headphones. When listening to your personal music player, opt for noise-canceling headphones, or go retro with older muff-type headphones. These block out background noise and allow you to have the volume lower. Ear-bud style headphones and in-the-ear headphones are less effective at drowning out background noise. Try to take regular breaks from your headphones, though, to give your ears a rest.
5. Turn down the dial. Turn down the volume on your TV, radio or hi-fi a notch. Even a small reduction in volume can make a big difference to the risk of damage to your hearing. If you need to raise your voice to be heard above the sound, turn it down.
6. When listening to live music, use ear plugs. They can reduce average sound levels by between 15 and 35 dB. They’re widely available at many live music venues and shouldn’t spoil your enjoyment of the music.
7. Don’t put up with work noise. If you’re experiencing noise at work, talk to your human resources department or your manager and ask for advice on reducing the noise and getting hearing protection.
8. Wear ear protectors (earplugs or earmuffs). These will protect your hearing if you are using noisy equipment such as power drills, saws, sanders or lawn mowers.
9. Be careful in the car. Listening to music in a confined space increases the risk of hearing damage. Don’t listen to music too loud for too long.
10. Have an "aural detox". Give your ears time to recover after they’ve been exposed to loud noise. According to Deafness Research UK, you need at least 16 hours of rest for your ears to recover after spending around two hours in 100 dB sound, for example in a nightclub or at a rock concert. Reducing this recovery time increases the risk of permanent deafness.
• Source: NHS Choices