When people in Wisconsin think of the dangers that farmworkers face, they might envision extreme heat, malfunctioning machinery, or even unruly livestock. But they might be unaware of another serious threat: Hearing loss.

Melanie Buhr-Lawler, a clinical associate professor of communication sciences and disorders at the University of Wisconsin-Madison, has spent a lot of time thinking about the auditory health of rural Wisconsinites. Growing up on her family’s dairy farm near Viroqua, she knows that rural areas aren’t always quiet. People across less populated parts of Wisconsin are exposed to noise from sources including agricultural equipment in fields, motor vehicles, industrial manufacturing machinery in factories, and guns.

Buhr-Lawler leads an outreach project to help rural Wisconsinites guard against hearing loss. In a July 1, 2015, talk at the Wednesday Nite @ The Lab series on the UW-Madison campus, recorded for Wisconsin Public Television’s University Place, Buhr-Lawler and research assistants Rachael Jocewicz and Timothy Kuckuk detailed how hearing loss can harm people across Wisconsin, and described their efforts to prevent it.

At her father’s suggestion, Buhr-Lawler took her message to a tractor pull in Tomah. She and her colleagues have returned to the event for several years running, distributing thousands of earplugs and educating attendees about the damage that loud tractor engines can inflict upon their hearing.

In their talk, Jocewicz offered explained the inner workings of the ear, while Kuckuk went into detail on the mechanisms of how noise damages hearing over time. Buhr-Lawler provided a bigger picture about the prevalence of hearing loss across society, focusing on the public policies and cultural attitudes that aggravate the problem in rural areas, explaining how a simple issue can be much more important than people think.

Key facts

• Audiologists define noise two ways: An unpleasant sound, or any sound, even if it’s pleasant or desired.
• Noise exposure can lead to expected consequences like hearing loss or tinnitus. But it has equally important impacts on people’s mood and stress level, ability to communicate, concentration, and workplace absenteeism and accidents. It can cause physical effects like muscle tension and hypertension, and can contribute to mental health conditions, including depression and dementia.
• Many of the harmful effects of noise result from prolonged exposure, but brief periods of noise exposure can do significant damage as well. The time over which one is exposed to the noise and the intensity of the sound itself are both important factors.
• People can’t compensate for noise-induced hearing loss by simply turning up the volume on amplified devices or asking others to speak more loudly because the malady actually damages the ear’s hair cells, which make it harder for the brain to interpret auditory information.
• The tiny stapedius muscle protects the ear against loud noises that come from within the body, like loud speech or chewing, but doesn’t safeguard against abrupt external noise.
• The decibel is a unit of measurement that quantifies the intensity of sound, but the scale is logarithmic, not linear — an increase of 10 decibels actually means a tenfold increase in sound power.
• Some common benchmarks for decibel levels in everyday life are the hum of a fridge (45 dB), average conversation volume (60 dB), and traffic noise (85 dB). Crowd noise levels at a recent well-attended Badger football game at Camp Randall Stadium in Madison measured at 96 dB. An MP3 player at peak volume is 105 dB, and rock concerts and chainsaws both rank at about 110 dB.
• Federal workplace safety regulators uses the 90 decibel rating as a benchmark. Regulations require that employees exposed to that level of sound for more than eight hours per day be offered hearing protection.
• Farmers often are not subject to Occupational Safety and Health Administration regulations that require workers exposed to noise to use hearing protection.
• Forty-eight million Americans have experienced hearing loss. So too have about 60 percent of American military veterans returning from tours in Iraq or Afghanistan; hearing loss is. considered the most common war wound among veterans.
• Researchers at Harvard discovered that people with hearing loss earn less than people with normal hearing and are unemployed at a higher rate.
• Buhr-Lawler’s recommendations for preventing hearing loss are simple: People should wear earplugs or earmuffs when they are exposed to loud noise.

Key quotes

• Buhr-Lawler on why any sound can count as noise: “The fact behind loud sound is that whether it’s something that’s wanted, or something that’s unwanted… if you’re exposed to enough of that sound over time, or even if you’re exposed one time to a very loud level, it can do permanent damage to your auditory system. And our auditory system is a very crucial component in our ability to connect with other people.”
• Buhr-Lawler on new hearing-loss trends: “We’re starting to see a noise-induced hearing-loss epidemic in the younger population that’s starting to mimic what was showing up for people who had worked in factories their whole lives… and we’re doing it to ourselves.”
• Buhr-Lawler on farmers’ attitudes toward noise: “Noise is just part of that culture, and it’s something that is accepted and not really thought about, at least in my background and the background of the people around me growing up.”
• Jocewicz on the importance of the outer hair cells within the inner ear: “If we do not have outer hair cells, we typically have a hearing loss on the order of 40 to 50 decibels, minimally… These hair cells are typically the place where noise causes damage.”
• Kuckuk on the significance of permanent ear damage: “When I say permanent, I really mean it. There is work that’s being done on trying to regenerate hair cells — actually work that’s being done at this university — but so far we haven’t been able to do that.”