Dancing in the din
Recent measurements in the din of San Francisco night spots revealed conditions in the most popular club that would endanger the hearing of the customers and employees in less than five minutes of continued exposure. Other night venues were a little less noisy, but all of those included in the survey played their music at toxic levels. And all were in violation of the Californian laws governing noise in the workplace.
The results of the survey were published by Hearing Education and Awareness for Rockers, H.E.A.R., a San Francisco based organization focusing on hearing disorders and their prevention among musicians and music lovers. The survey made measurements in a dozen clubs and found the most popular club, the Sound Factory, to be the noisiest with an output as high as 105 dB. In the least noisy club in the survey, Holy Cow, the sound level was recorded as 94 dB.
The California Occupational Safety and Health Administration (CAL-OSHA) admits that a lack of resources prevents the agency from routinely monitoring the clubs. Workplace rules require that employees working in sound levels above 85 dB wear ear protection, be given regular hearing exams and be provided with a hearing loss education program sponsored by the employer. In addition, warning signs must be posted in areas where hearing protection is required.
In some of the clubs, the recorded noise levels are so high that CAL-OSHA recommends that employees wear earplugs as well as earmuffs. However, no state rules and regulations are in place to protect the clubs' customers from the noise, but the city of San Francisco is now requiring that earplugs must be available to the patrons in large night clubs.
The safe level of noise is often defined as 85 dB of continuous noise output in up to eight hours. At 105 dB, as measured in the Sound Factory, the maximum safe continuous exposure according to the U.S. National Institute for Occupational Safety and Health (NIOSH) guidelines is 4 minutes and 43 seconds. At Holy Cow's 94 dB exposure beyond one hour a day brings serious risk of hearing loss.
Source: H.E.A.R. (www.hearnet.com), 2002