Ted Nugent once played a concert in Kansas City that was so loud he received complaints from farmers who lived eighteen miles away. Now, if the Motor City Madman’s high end made the heifers low way out there, you can imagine what it sounded like to Nugent, who was standing less than a foot from the amplifier that was producing those “overwhelmingly beautiful decibels.”
Overwhelming, yes. “I guess I noticed it about ten years ago,” Nugent said. “I couldn’t hear people talking on my left side when there was background noise, and I had trouble hearing on the phone through my left ear. But it wasn’t surprising. When it comes to playing loud, I got an attitude of overkill.”
Nugent discovered that he had suffered a hearing loss of nearly twenty percent in his left ear, and now wears earplugs during his concerts. “It hasn’t gotten any worse since it was diagnosed,” he said, “and it’s really not all that bad. It doesn’t interfere with my music or hunting. I’m still the first to hear a pheasant sneaking across the gutter.”
Nugent’s hearing loss may, in fact, be more related to his sport shooting than his guitar. But that didn’t make much difference to concerned audiologists in the late Sixties and early Seventies. Armed with statistics that showed, for instance, that a significant percentage of freshmen entering the University of Tennessee displayed high-frequency hearing impairment, researchers began to show up at rock concerts with banks of testing equipment. They measured the hearing thresholds of musicians and fans before and after exposure to amplified sound and, as expected, rock & roll, already blamed for a host of other social ills, was tagged as the culprit.
The hue and cry that reverberated throughout the scientific community prompted a wave of legislative attempts to restrict sound levels in recreational establishments. In England, the Leeds governing body adopted a noise code that effectively prohibited any loud band over ninety-six decibels from playing there. Several local boards of education in the United States set noise limits for bands playing at school dances. And several cities, including Los Angeles, adopted a model noise ordinance requiring concert halls and nightclubs to post a sign warning patrons of hazardous sound levels.
Recent studies, however, including several conducted by researchers who were among the first to ring the sonic death knell for rock musicians and fans, contradict the negative findings, extending the controversy. While nearly all researchers agree that overexposure to amplified music is dangerous — the New York League for the Hard of Hearing found that more than thirty percent of the disco DJs in New York have suffered significant hearing loss — audiologists now claim it is just one of many modern environmental noise sources that can impair hearing. Which means that exposure to Nugent may be no more hazardous than exposure to factory noise, the roar of a snowmobile or the high-pitched screams of food processors and vacuum cleaners.
Almost everyone who has attended a rock concert or discothèque has experienced a temporary threshold shift in hearing, or an inability to detect weak sounds. The decreased sensitivity may last for minutes, hours or days and is often accompanied by a ringing in the ears. The ringing may be an indication that damage has occurred to the hair cells in the inner ear, which are part of the sensory apparatus that converts mechanical stimuli — noise — into neural impulses. The damage may be minimal, but repeated exposure can result in a permanent shift, for which the only remedy is a hearing aid.
“The nerve endings are destroyed, physically torn apart by noise assault,” said Dr. Thomas H. Fay, director of speech and hearing at Columbia-Presbyterian Medical Center in New York. “If you can just picture tossing a bomb randomly into a telephone switching-exchange building, then you can see the randomness of damage. You haven’t the faintest idea what connections and relays are going to be destroyed.”
Overexposure to noise sometimes causes tinnitus, the ringing in the ear that can disappear in a short time or follow you to the grave. “Too many people have gone and jumped out the window after they’ve been told they will have to live with that,” said Dr. Fay.
Many rock musicians and audience members have suffered some sort of damage to the ear. But there is a considerable range of opinion on whether amplified music by itself can cause this damage. Among the variables considered by researchers today are the source of sound (live concerts, earphones or home stereo equipment), length of exposure versus recovery time, a subject’s history of industrial noise exposure, drugs in the body, individual sensitivity and even the attitude a person brings to his listening experience.
William F. Rintelmann, professor and chairman of audiology at the University of Pennsylvania School of Medicine, recently provided researchers with the first longitudinal study of noise-induced hearing loss among rock musicians. Beginning in 1967, he screened 150 musicians to arrive at a sample of forty-two who had a clean otological history, that is, no chance of hearing loss for reasons other than music. Forty of these musicians in 1967 showed no sign of hearing loss. In 1971 he called back ten of the musicians for further testing and found that their hearing had not changed. By 1975 his sample was down to six musicians.
“We found over a seven-year period that four of the six musicians’ hearing had not changed,” Rintelmann said. “One musician showed a very mild high-frequency loss, but it was still within normal limits. The other had a slight hearing loss. That leads us to say that there’s a certain amount of susceptibility to noise damage from rock music, but it’s not dramatic.”
Rintelmann also studied a group of 120 college students. equally divided among regular and infrequent listeners of rock music. He found no difference in the hearing of these two groups.
Many of the negative conclusions reached in the early Seventies resulted from comparison of concert sound levels with federal workplace noise standards. According to guidelines adopted by the Occupational Safety and Health Administration in 1970, an American worker cannot receive a noise dose of over ninety decibels (db) for more than eight hours a day. Because the decibel scale is logarithmic, ninety db is twice as loud as eighty; a hundred db twice as loud as ninety. The daily noise-level limits, then, range from ninety decibels for eight hours to 115 db for fifteen minutes.
Applying those standards to sound levels measured in studios, concert halls and discos may have gotten researchers off to a false start. Many found that concert sound levels peaked higher than 120 decibels, which approaches the threshold of pain. However, most of those readings measured peak sound level rather than equivalent, or average, sound level. According to Peter George, an engineer with Acoustic Noise Control Consultants in New York, “heavy metal” music averages in excess of 110 decibels, stereos put out as much as 110 db and more, and discos reach peak levels in excess of 125 db. By workplace standards, a concertgoer or musician should only be exposed to 105 db for a maximum of one hour daily — considerably less time than the average double-billed concert.
“You have to remember that you don’t have this kind of exposure five times a week,” said W. Dixon Ward, director of the Hearing Research Laboratory at the University of Minnesota. “It’s a fluctuating noise, the musicians take breaks, and the ear has a chance to recover.”
Other researchers have exposed animals to high levels of sound for long periods and have found resultant damage to the inner-ear hair cells, which causes permanent hearing loss. But some researchers now believe that predicting comparable effects in human hearing based on these experiments may be misleading.
“I think we may have been generalizing inaccurately from the animal studies,” said David M. Lipscomb, a professor of audiology and speech pathology at the University of Tennessee who at one time thought rock music to be a major cause of hearing loss. “Subsequent research has found extremely viable attitudinal factors involved in noise-induced hearing loss. An animal simply doesn’t have the high-level attitude-shaping capabilities that a human does. An individual who likes what he hears can probably introduce something of a protective element into his sound exposure. If you are exposed to high-level sound and become distressed by it, this seems to increase your susceptibility to noise damage. Which means that the person most in danger at a rock concert is the chaperone.”
The ear does have a built-in mechanism, called “acoustic reflex,” that can mediate susceptibility to damage. It’s triggered when noise has reached a dangerous level. When the acoustic reflex fires, the stapedius muscle in the middle ear contracts and reduces the efficiency of noise traveling to the nerves in the inner ear. But because it is a muscle — the smallest one in the body, in fact — it will tire and is not protective for long periods of time. Researchers have also found that the stapedius can be affected by drugs.
“Alcohol has been shown to weaken the ability of the stapedius muscle to contract,” said Dr. Maurice Miller, professor of audiology at New York University and chief of audiology at Lenox Hill Hospital. “With a high intensity of noise and the ingestion of alcohol and various other substances, the inner ear is rendered highly susceptible to severe damage.” Studies show that barbiturates can also adversely affect the stapedius, and it is suspected that marijuana, antibiotics and even aspirin can cause problems.
Conclusions drawn from future research will no doubt vary as widely as those circulating now. Dr. Miller, for instance, thinks it likely that exposure to 100 decibels for fifteen minutes on a weekly basis will produce hearing damage. But the rock musicians in Rintelmann’s study were exposed to approximately 105 decibels for an average of eleven hours per week for three years and suffered no hearing loss.
All researchers agree that the dangers are real. Worse, hearing loss is not detectable until it is permanent.
Which means that the individual rock & roller will have to decide for himself about ear protection. A person who rides a motorcycle to a job in a noisy factory should probably think seriously about protecting his ears before getting a dose of decibels from Nugent. But a librarian could possibly listen to him every night and suffer no damage — at least to his or her ears. Thresholds and tolerance levels vary from person to person, but it’s best to remember that whatever you’re listening to, it’s all noise to your ears.