PLAINFIELD - When John Deere tractors are assembled in Waterloo, workers are required to wear hearing protection.

When the green machines get in the field, it's up to the farmer to decide. And according to health experts, too many are not wearing earplugs or muffs, causing permanent hearing loss and putting them at greater risk for farm accidents.

As producers take to the fields this fall to chop silage and combine corn and soybeans, many will be doing it from the comfort and quiet of a near sound-proof cabs. But as soon as they step out of the hearing-safe sanctuary, they're often bombarded with noise loud enough to eventually cause noise-induced hearing loss. That goes for a myriad of other harvest and fall farm activities.

Loud conditions created by tractors, combines, grain dryers, chainsaws, livestock and other things create a hazardous work environment. According to a University of Iowa College of Public Health study earlier this year, farmers who had difficulty hearing normal conversation are 80 percent more likely to suffer an injury related to a fall. Those wearing hearing aids were twice to more than five-times more likely to get injured depending on the task or activity.

To Dr. Nancy Sprince who headed the hearing study of 7,000 Iowa farmers, the choice is obvious: wear earplugs or muffs regularly.

"During harvest, working near noisy machinery for long periods of time, eventually you won't be able to hear what your parents are saying," Sprince said of farmers who refuse to protect their hearing. "You'll double (or more) the risk of injury. You can't hear the warning signs, the change in animal noises or malfunctioning machinery."

The study's participants were pulled from a larger Agricultural Health Study of 30,000 farmers by the university. Of those randomly selected to participate in the hearing screening, 431 were chosen for the case group and 473 for the control group. Case group farmers said they were injured on the job in the past year and the control group were not.

Hearing aid wearers are 2.4 times more likely to be injured on the job, 5.4 times more likely to get hurt by an animal and 4.4 times more likely to suffer a machinery-related injury.

Sprince said about 75 percent of farmers asked don't wear hearing protection when they should, or enough of it when they do. Even if they get out of the cab for a few minutes to hook up a wagon, she said they still should protect themselves.

"I would suggest it because it does add up. Poor hearing is the strongest predictor of injury, even more than age or hours worked," she said.

Sprince said farmers should wear earplugs or muffs when doing any activity exceeding 85 decibels. For example, running grain dryers, combines and even riding lawnmowers warrant protection. Normal conversation averages 60 decibels, she said.

Gloria Dielschneider, Grundy County Public Health nurse and AgriSafe - a statewide agriculture safety program - coordinator, said loud noises cause the hair in the inner ear, or cochlea, to break or bend. The hair collects sound and helps people hear.

"Once the hairs are damaged, they're gone and you'll never get them back. Higher frequencies are lost first," Dielschneider said. "The farmers I've seen, easily over half have significant hearing loss."

Ken Simmer, a 59-year-old farmer near Waverly, readily admits he doesn't wear earplugs as much as he should. He predicts he'll have to wear a hearing aid some day as a result.

Still, Simmer spent Monday helping his friend, Rick Juchems of Plainfield, fill silo without hearing protection. He drove a small tractor without cab to haul chopper boxes full of corn silage from the field to the blower, which is powered by a large diesel tractor.

Standing next to the blower shooting silage up a pipe 75 feet, the noise is almost deafening. Sprince said it probably well exceeded 115 decibels - rock concert level.

"I don't do it (wear ear plugs) as often as I should. I don't know, it's stupid," Simmer said.

Health officials and farm experts say farmers come up with a variety of excuses for not wearing hearing protection. Some say it's not convenient, they don't remember because it's not a habit or they're afraid they won't be able to properly hear equipment if something breaks or clogs.

Some farmers say they didn't do it growing up, so why start now, Dielschneider said. Decades ago, hearing protection wasn't stressed on the farm like today, she said. That's come with education and medical discoveries.

"You want to protect what hearing you have left," Dielschneider said.

In the cab of Juchems' 1992 Case-IH tractor Monday it's fairly quiet, even pulling a two-row silage chopper chewing up corn and spitting it out. He has to crack a window to hear if the equipment is operating properly.

Juchems prides himself on being safe - wearing ear protection most of the time and keeping all safety shields and guards in place - but if he had to get out of the cab, his ears wouldn't be protected. A hearing test four years ago showed the inability to hear high-pitch sounds, the 51-year-old said.

"If I know I'll be around loud (noises), I try to be safe," Juchems said.

The National Hearing Conservation Association says early warning signs of noise-induced hearing loss are:

- Ringing in the ears.

- A sensation of "fullness" in the ears.

- Some reduction in the ability to understand conversation.

Of the trio filling silo Monday, only Paul Regenold of Charles City put in foam earplugs before starting for the afternoon. After working in the foundry and retiring from John Deere in Waterloo, he said wearing earplugs is second nature.

The row-crop farmer said his hearing hasn't changed in 27 years.

"When you get old you start losing it, but why lose it prematurely?"

AgriSafe provides free hearing checks for farmers. Call 1-866-312-3002 to find the nearest participating clinic, or go online at www.agrisafe.org.

Contact Matthew Wilde at (319) 291-1579 or matt.wilde@wcfcourier.com.