It should come as no surprise that military personnel who spend time on the mortar range or in close proximity to jet engines are in danger of hearing loss. What's less commonly known is that housework can be equally as hazardous.

"Most vacuum cleaners are loud enough that exposure for extended periods can cause nerve damage," said audiologist Jaclyn Knutson, hearing services coordinator at Clarus Eye Centre, which has offices in Lacey and DuPont.

That's not an excuse to abandon housework - it's a warning to wear protective gear whenever you're exposed to loud ... ah, let's call it noise.

"You might go to a rock concert when you're a child and another when you're in your teens and another when you're in your 20s and not begin to experience hearing loss until you're in your 30s," Knutson said.

The damage is cumulative.

Any time you've experienced a noise that left your ears ringing - a sensation called tinnitus - you've probably suffered nerve damage, she said.

Chances are your hearing has already been damaged through years of activities you considered safer than falling off a log. But it's never too late to take precautions, she said, adding that the most effective noise dampers are those that look like earmuffs. Obviously, earmuffs would be considered gauche at most rock concerts, but fans who find it impossible to resist attending should get a seat as far from the amps as possible.

Those for whom Knutson's advice comes too late to save their hearing can take solace in the advances computerization has made possible in hearing aids.  First the good news: during the past five years, hearing aids have all gone digital. When wearing one, you're carrying a tiny computer in your ear.

This digitization of hearing aids allows the wearer to take advantage of Bluetooth technology, a system that uses short wavelength radio transmissions, making it possible not only for the hearing impaired to keep their phones hands free, but also hear calls more clearly.

"The caller's voice isn't being filtered through the phone's receiver - it goes directly to the hearing aids," explained Knutson.  This allows the wearer to hear the phone in both ears at a volume appropriate for the wearer's hearing loss.

The system also enables a direct link to televisions and most any other entertainment or communication devices commonly found in modern homes. The direct link eliminates, or at the very least dramatically reduces, extraneous sound. Computerization also enables Knutson to adjust filters so that other forms of white noise are less intrusive than with earlier hearing aids. 

"The most expensive hearing aids have a 25 decibel noise reduction," she said. "They filter out background noise and focus their hearing on whatever the wearer is looking at."

Now for the bad news: the significant advances in technology have not been able to reduce the price of hearing aids.

You can expect to pay as much as $6,600 for a pair of premium hearing aids or as little as $1,900 for an economy pair. In the mid-range are devices with rechargeable batteries. A good rule of thumb for anticipating what an individual will have to pay is the more extensive the hearing loss, the more expensive the hearing aids will be. If there's a silver lining, it's that Knutson worked for a nonprofit when she began her career and learned a good many tricks that can make a big difference to patients whose budgets don't stretch all the way to the upper end of the price range.

"I learned how to get the most out of even the least expensive hearing aids," she said.