October 5, 2007
MELVILLE, NY—The Acoustical Society of America (ASA) announced on Tuesday (September 24) the American National Standard Methods of Estimating Effective A-Weighted Sound Pressure Levels When Hearing Protectors are Worn (ANSI/ASA S12.68-2007).
This standard is expected to be valuable to managers, industrial hygienists, and hearing conservation professionals responsible for selecting and assigning hearing protectors for noise-exposed workers: military and law-enforcement personnel; manufacturers of hearing protectors; hearing protection testing laboratories; acoustic consultants; and regulatory agencies. Though rating and computational methods have been previously described in the literature, as well as in governmental publications and regulations, this is the first time that an American National Standard specifies such procedures.
This standard specifies three methods, in ascending order of complexity of use and potential accuracy, for the estimation of the sound pressure levels (SPLs) that are effective when a hearing protector is worn.
The simplest of the methods is similar to the well-known NRR, but diverges in two key aspects: namely it can be used with A-weighted sound pressure levels instead of requiring the use of C-weighted levels, and instead of specifying a single number at the 98th percentile, it provides values for the 80th and 20th percentiles. This standard is accompanied by an informational spreadsheet programmed to perform the calculations specified in the standard itself. This Standard was developed by Accredited Standards Committee S12, Noise, under operating procedures accredited by the American National Standards Institute (ANSI). These procedures assure that the Standard represents the consensus of opinion among those with a direct and material interest in the subject matter. The standard was drafted by a working group comprising experts from all segments of the hearing conservation community.
This standard and many other national and international noise standards can be obtained from the Acoustical Society of America Online Store. Or, order by phone, fax or mail from: Acoustical Society of America, 35 Pinelawn Road, Suite 114E, Melville NY 11747 3177; phone: 631-390-0215; e-mail: [email protected].
ASA offers the full catalog of ISO/TC108, ISO/TC43, and IEC/TC29 standards, as well as a wide range of American National Standards on the topics of Acoustics, Mechanical Vibration and Shock, Bioacoustics and Noise.
Marshall Chasin, AuD, and Lee D. Hager co-edited a special edition of The Hearing Review in March 2007 which includes articles on Acoustics and Hearing Protection Devices , Earmuffs, Current Standards and Pending Developments, the Choosing and Use of HPDs, and Firearms and Hearing Protection, among other topics. Additionally, Maurice Miller, PhD, edited a special September 1999 edition of HR on the topic of occupational hearing testing and conservation (not currently archived online) which includes articles by John Franks, PhD, Julia & Larry Royster, PhD, John Earshen, MS, John Erdreich, PhD, David Lipscomb, PhD, Elliott Berger, MS, and George Cook, MEd.