But those NASCAR fans, as well as the pit crews and drivers, are being exposed repeatedly to extremely dangerous levels of noise -- as high as 140 decibels -- according to extensive studies of three popular race tracks by federal investigators.
Decades of research at scores of different work settings led scientists, physicians and safety specialists at the National Institute of Occupational Safety and Health to determine that the most noise workers can be exposed to on the average eight-hour work day is 85 decibels. The Occupational Safety and Health Administration adopted that level as the national maximum, legal noise level.
NIOSH scientists Chucri Kardous, a research engineer, and Thais Morata, a research audiologist, did multiple tests at the Brickyard at the Indianapolis Motor Speedway, Tennessee's Bristol Motor Speedway and the Kentucky Speedway in Sparta.
Sound measurements were conducted using sound level meters, personal noise dosimeters, and digital audio recorders that made sound recordings for later laboratory analysis. The measurements were made during race preparation, practice, qualification, and competition. Individual measurement devices called dosimeters were placed on drivers, team members, and spectators.
They found that the OSHA eight-hour limit was exceeded in less than a minute for a driver during practice, within several minutes for his team members, and in less than one hour for spectators during the race.
What this means is that a driver's noise dose was 50-900 times higher than the allowable occupational daily noise dose set by the federal government, the researchers reported.
NASCAR did not immediately respond to calls for comment today.
It's not a fleeting hazard, Morata told AOL News.
She and her partner determined that race team members -- drivers, fuelers, mechanics and the rest of the pit crew -- receive 12 to 21 hours of "intensive noise exposure" every week up to 40 consecutive weeks and more during the off-season.
Think of the spectators, wedging themselves as close as they can get to the roaring 750-horsepower engines making 500 or so laps around the oval tracks, sometimes at speed greater than 200 mph; the noise becoming even more damaging and ear-splitting as the cars blast down the superspeedway or straightaway.
The team from NIOSH, which is the worker safety research arm for the Centers of Disease Control, determined that spectators are exposed to a noise dose that is two to 10 times higher than a person working a 40-hour week at the maximum allowable limit of 85 decibels.
Their measurements showed that spectators in the stands during a race were surrounded by 96 decibels of noise. A driver inside a car during practice got 114 decibels; in the pits, noise reached or exceeded 130 decibels, a level often recognized as the human hearing threshold for pain. During the race, peak sound levels pushed the meters to 140 decibels.
To understand how loud is loud, normal conversation is 50 to 60 decibels. Urban traffic is about 70 decibels and for heavy trucks, add another 20 points. The loudest alarm clock comes in at about 80 decibels, a snowmobile or chainsaw registers at about 90 to 100 decibels, a jet taking off generates about 120 decibels and heavily amplified rock music can reach 150 decibels.
The pit crews and some spectators are likely to have greater hearing impairment because they are exposed to louder noise than the driver, who is usually protected by using custom-molded earplugs with built-in speakers.
What makes the NIOSH research so alarming is that the hearing damage inflicted from these levels on those involved or watching the races is cumulative and mostly irreversible.
"Most people love the noise, are attracted by it because they relate it to power and many know the risks involved," Morata said in a interview, "but they may not know that the damage can be permanent."
The hazard to hearing varies depending on the number of cars racing, track conditions and design.
On Friday and Saturday there is another major race at Tennessee's Bristol Motor Speedway.
It holds the title of the noisiest track on the NASCAR circuit, NIOSH says. Its bowl-shaped layout is much like a football stadium, the track is small and the metal stands amplify the sound and causes it to reverberate.
"Earplugs are for sale there and I wonder how many people will buy and use them," Morata said.
While the likelihood of hearing damage has been well quantified, the extent of the injuries has not been determined.
But NIOSH Director Dr. John Howard said the research findings were important and should be heeded.
"Drivers, pit crews, and other workers at NASCAR's tracks are justifiably proud of being part of a tradition that millions of people enjoy. At the same time, it is important to be aware that occupational exposures to excessive noise can lead to hearing impairment and tinnitus, and that protections are available and recommended for lessening this risk."
The study on workers and spectators at stock car races is the second of three studies that NIOSH is conducting on hearing dangers posed by sporting and recreational events.
The first was on the African vuvuzelas, the plastic horns that drowned out most other sounds at the World Cup Games. The final research will be on hearing damage from exposure to music, including symphony orchestras, marching bands, rock and rap groups and record DJs.
"I believe people will be amazed to learn what the noise levels are at the various music venues, for performers and spectators alike," she said.
For additional information, read the NIOSH Science Blog.