Would You Please Repeat That?

According to Bob Halstead, the Aussie scuba pioneer and diving guru, most married men understand selective deafness. “This is attained by training over many years to automatically tune out sentences with words like ‘washing up,’ ‘garbage,’ ‘shopping,’ and tune in to words such as ‘dinner,’ ‘wine,’ ‘sex,’ etc. Women must understand that this is a kind of defense system that enables men to survive marriage,” he writes in the amusing and occasionally tongue-in-cheek piece “Speak Up!” in the February issue of Dive Log Australasia.

But the real focus of his article is about how male divers suffer from the true affliction of high-frequency hearing loss, more so than women. “This problem advances with age, number of dives and whether the diver has done much freediving or only used scuba. [They] can seriously damage their ears if they fail to clear their ears thoroughly and regularly, ending up with tinnitus.”

Halsted, who has tinnitus and high-frequency loss, blames diving for the difficulties in carrying on a conversation in a noisy restaurant. During a lunch with Jean- Michel Cousteau and Aussie diving luminaries Ron and Valerie Taylor, Barry Andrewartha and Belinda Barnes, Mike Ball and Phil Nuytten, Halsted had to lean forward and cup his ear to hear. “Then I made a startling observation - - all the men were doing the same thing.”

The article got us thinking about the known ramifications of scuba on our auditory well-being. Published research distinguishes between acute diving-related damage to the ear, like those caused by infection barotrauma and DCI, and insidious decreases in hearing from a history of injury or excessive noise exposure. It’s clear that sport divers sustain a variety of acute injuries to the ear with permanent effects such as tinnitus, hearing loss and balance disorder. Fortunately, proper ear hygiene frequently can prevent this type of injury, and common sense can prompt expert attention when ear problems do arise.

But does scuba automatically result in hearing loss in divers with no history of immediately identifiable injury? The first thing to appreciate is that hearing acuity routinely diminishes with age, diving or no. Hearing loss is the third most common health problem in people over age 65. Agerelated hearing loss occurs slowly and usually isn’t noticed until later in life, but it definitely happens. Indeed, it is indeed more common in men than women. Difficulties in hearing human speech typically are noticed first, and high ambient noise often compounds the difficulty. As such, Halstead and his tablemates, some of whom began diving four or more decades ago, shouldn’t be too hasty in indicting scuba as the sole cause of their communication issues.

Demonstrated reductions in hearing are far more prevalent and severe in occupational divers. As a group, commercial divers, including younger ones, are subject to hearing loss caused by damage to the inner ear. Sport divers, on the other hand, seem to escape the diminishment in hearing seen in commercial scuba divers. This likely is due to minimal exposure to ear-punishing decibels of noise underwater and to diving far less frequently on average.

In a 2006 study by Australian researchers published in the Undersea & Hyperbaric Medicine Journal, 16 experienced recreational divers with an average of 725 dives each under their belts were tested along with 16 non-divers of the same demographics. All were age 55 or under and had no history or likelihood of hearing loss. The tests found no significant differences in either air or bone conduction studies, nor pure tone or high frequency averages. The only exception was a significantly greater loss of acuity in divers at a high-frequency hearing level of 6,000 hertz, the upper level of hearing range to decipher human speech (vowel sounds have lower frequencies of 250 to 1,000 Hz and are easier to hear, while many consonants have higher frequencies of 1,500 to 6,000 Hz). This conclusion is consistent with other contemporary work indicating no meaningful differences in hearing thresholds between sport divers and non-divers.

Given the science to date, recreational scuba divers who avoid preventable ear injuries need have no undue worry about hearing impairment as a result of diving. And if future research proves otherwise, don’t fret. Chances are you’ll be more able to find a quiet place for a drink, so scuba to your heart’s content.

-- Doc Vikingo