Roar of the Crowd Carries Hearing Hazard

EDMONTON, Alberta, Dec. 4 -- When enthusiastic hockey fans get into it, the sound in an indoor arena can soar to the level of a jet aircraft taking off, with the risk of permanent hearing damage.

A case in point was last year's National Hockey League finals at Rexall Place here, when levels spiked to more than 120 decibels (dB A) when the hometown Oilers scored, according to William Hodgetts, a Ph.D., candidate at the University of Alberta.

In three of the games in the series, fans had a noise exposure of 104.1, 100.7, and 103.1 dB A, respectively over three hours, Hodgetts and a colleague reported in the Canadian Medical Association Journal.

"An average level of 85 dB A for eight hours is generally considered the maximum allowable daily noise dose," the researchers noted, and the risk of hearing damage increases sharply as the level of the logarithmic decibel scale rises.

The researchers noted that each three dB increases in average noise level cut the safe exposure time in half, so that at 88 dB, the maximum allowable daily noise dose is reached after four hours and at 91 dB it is reached after two hours.

For the third game of the series, fans reached the maximum allowable daily noise dose in less than six minutes, the researchers said, and unless they were wearing hearing protection, fans got 8,100% of their daily allowable noise dose over the course of the game.

"Given that most fans do not wear hearing protection during hockey games, thousands are at risk for hearing damage," the researchers said.

For the study, researcher Richard Liu, M.D., of the University of Alberta, was equipped with a data-logging noise dosimeter, and he and his wife had their hearing tested before and after each of the three games.

Only the results from the third game were reported in detail.

Pure-tone audiometric data showed that the hearing thresholds of both participants deteriorated by between five and 10 dB for most frequencies, with the biggest changes at 4,000 Hertz, which is the frequency known to be most susceptible to noise damage.

One participant had a temporary threshold shift in one ear of 20 dB, which "represents a real change in hearing status," the researchers said.

Such a shift usually disappears within a few days, but further noise exposure before full recovery may cause the change to become permanent, they noted.

"Both subjects described the world as sounding muffled after the games, and both experienced mild ringing tinnitus," the researchers reported.

Dr. Liu and Hodgetts noted that even cheap earplugs would reduce the noise exposure by 25 to 30 dB, which -- at the levels experienced during the games - "would drop the average sound exposure to below 80 dB, where no hearing damage is likely to occur."

The Carolina Hurricanes won the best-of-seven series four games to three.