![]() ![]() The Epidemiology of Hearing Loss Study (EHLS) is a population-based study of hearing loss in adults 48–92 years of age ( Cruickshanks et al, 1998). Consequently, the purpose of this study was to compare four algorithms for identifying audiometric notches ( Coles, Lutman & Buffin (2000) McBride & Williams, 2001 Dobie & Rabinowitz, 2002 Hoffman et al, 2006) using data from a population-based cohort study of older adults. Validation studies as well as studies comparing algorithms among older adults are still needed. Since the present study focused on older adults, these three studies were not considered further here. Three of these ( Kramer & Wood, 1982 West & Evans, 1990 Niskar et al, 2001) were carried out among children and young adults who typically have fewer competing factors contributing to the audiometric shape, thus making notches more easily recognized. Several studies have suggested algorithms to more objectively define the presence of a notched audiogram ( Kramer & Wood, 1982 West & Evans, 1990 Coles, Lutman & Buffin, 2000 McBride & Williams, 2001 Niskar et al, 2001 Dobie & Rabinowitz, 2002 Hoffman et al, 2006). The poor agreement among the three raters indicated visual inspection of the audiograms was not a reliable method for identifying notches. Intraclass correlations between the ratings of pairs of raters ranged from 0.14 to 0.52. Agreement between the raters was poor: Raters 1, 2 and 3 identified 26%, 49%, and 68% of the individuals as having a notched audiogram, respectively. In the McBride & Williams (2001) study, three raters with experience assessing audiograms (an otolaryngologist, an audiometrician, and an occupational physician) were asked to inspect the audiograms of 634 individuals (one audiogram for each ear) and assess whether a notch was present in the audiogram of either ear: a notch which, if a suitable noise history were obtained, would be attributed to noise exposure in that person. ![]() ![]() However, there is little agreement about a formal definition of a notched audiogram. A notched audiogram, together with a positive history of noise exposure, has been gradually accepted as a clinical sign of NIHL ( McBride & Williams, 2001). This may be reflected in the audiogram as hearing thresholds that reach a maximum between 3–6 kHz and then return toward the normal level at higher frequencies, forming a noise notch. Thus the worsening of sound perception typically starts in the 3–6 kHz range for people with NIHL ( Gallo & Glorig, 1964 McBride & Williams, 2001). The sensory cells in the basal portion of the cochlea concerned with the reception of sound at 3–6 kHz are more vulnerable to damage from noise than those tuned to lower and higher frequencies ( Johnsson & Hawkins Jr, 1976). People with NIHL have structural damage in their cochlea ( Rabinowitz, 2000 ACOEM, 2003). Motorcycle riding has also been associated with hearing loss ( McCombe & Binnington, 1994 McCombe et al, 1995), as has the use of firearms during hunting or target shooting ( Taylor & Williams, 1966 Prosser, Tartari, & Arslan, 1988 Nondahl et al, 2000). Noisy recreational activities like woodworking, metalworking, or the use of power tools have been associated with high frequency hearing loss ( Dalton et al, 2001). Non-occupational noise may also contribute to NIHL. Many Americans are exposed to hazardous levels of noise in the workplace, especially in industries using noisy machinery, such as metalworking, stone cutting, woodcutting, transportation, agriculture and the military. However, since multiple factors can contribute to hearing loss, the exact prevalence of NIHL is unknown.Įxposure to sufficiently loud occupational noise for extended periods of time, however, can increase the risk of developing NIHL. NIHL is a common type of sensorineural hearing loss. Noise-induced hearing loss (NIHL), as opposed to acute acoustic trauma, can be defined as hearing loss that develops slowly over a long period of time (several years) as the result of exposure to continuous or intermittent loud noise ( ACOEM, 2003). ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |