Attenuation Values of a Noise-Cancelling Headphone
By Baur, Francis X.; Zalewski, Thomas R.; Hearing Review,Publication Date: June 2008
Study seeking to determine the attenuation value provided by the Bose QuietComfort Noise-Cancelling Headphones in the presence of high-level white noise. The study was undertaken as noise-induced hearing loss, the second most common form of acquired hearing impairment following age, can be prevented by using protective devices that reduce the intensity level of the noise. A total of 30 volunteers without hearing impairment, with a mean age of about 23 years, participated in the project. A probe tube attached to an Audioscan Verifit system was put into the ear canal of each participant before the headphones were placed over their ears. White noise of 85 dBA produced by a computer program was presented via a speaker system into the sound field of the test room. The sound pressure level within both external auditory canals was measured individually with the Verifit system in the presence of the white noise. These measurements represented the attenuation of the white noise provided by the headset, while the difference between the dBA levels with and without the headset represented the level of noise reduction (NR) provided by the headset. Results indicated a significant reduction in the 85 dBA white-noise level in the ear canal upon placement of the noise-cancellation headset. The study concludes that the amount of NR provided by this technology is sufficient to allow for extended exposure to noise levels up to approximately 98 dBA, such as those in a machine shop, to remain within a safe listening level.
Assistive Products Discussed: VERIFIT
Published by: Ascend Media LLC (Website:http://www.ascendmedia.com)
Link to text: http://www.hearingreview.com/issues/articles/2008-06_03.asp?frmNewsletter=topten
