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Vuvuzelas blasted into the public's ears and awareness during the 2010 FIFA (Fédération Internationale de Football Association) World Cup in South Africa. One immediate question asked was if the cheap horns commonly made of plastic and blown by enthusiastic fans during sporting events pose serious risks to hearing.
Researchers from the Southern Polytechnic State University (SPSU), in Marietta, GA, and the Georgia Institute of Technology, in Atlanta, investigated the acoustics of vuvuzelas and the potential impact on hearing. They presented their findings at the annual meeting of the Acoustical Society of America held recently in San Diego.
The researchers found that the sound levels from single horns range from 90 dB to 105 dB at the ears of the person who blows it. They also discovered that the impact of the horns is greatest when blown simultaneously with many others, where the levels within an audience may approach 120 dB.
Richard Ruhala, PhD, program director of mechanical engineering at SPSU, provided perspective by explaining that 100 dB is the level of noise heard at a rock concert, and an ambulance siren or pneumatic jack hammer produces about the same level of noise as vuvuzelas in a stadium - 120 dB, which is at the threshold of feeling and produces a tickling sensation in the ears.
"The threshold of pain is 140 dB," Dr. Ruhala stated. "Sustained exposure to 120 dB is a thousand times the acoustic energy that causes hearing loss [with long-term exposure]. That's why OSHA requires people working near those noise levels to wear hearing protection."
He worked with his wife, SPSU researcher Laura Ruhala, and Kenneth Cunefare, PhD, professor of acoustics at Georgia Tech, to record the sound levels produced by a number of vuvuzelas, including one that had been used at the 2010 World Cup.
"On the field of play, with just a few percent of a stadium's audience blowing vuvuzelas, the predicted levels could exceed 90 dB, which is a level that would interfere with communication between players and impair their ability to hear the calls of officials," Dr. Cunefare pointed out. "At the end of the day, though, the use of these horns at sporting events is maybe as much a cultural and participation choice as anything else. Perhaps there's a product marketing opportunity here: Hearing protectors for sale at sporting venues in each team's colors?"
The researchers are continuing their work, analyzing the precision sound power and directivity of measurements already obtained. With the assistance of acoustic engineer Tina Ortkiese, they also are zeroing in on creating more accurate sound models to evaluate the sound pressure levels vuvuzelas produce in a stadium.
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