title: Prevalence of high frequency hearing loss consistent with noise exposure among people working with sound systems and general population in Brazil: a cross-sectional study.
abstract: BACKGROUND
  Music is ever present in our daily lives, establishing a link between humans and the arts through the senses and pleasure. Sound technicians are the link between musicians and audiences or consumers. Recently, general concern has arisen regarding occurrences of hearing loss induced by noise from excessively amplified sound-producing activities within leisure and professional environments. Sound technicians' activities expose them to the risk of hearing loss, and consequently put at risk their quality of life, the quality of the musical product and consumers' hearing. The aim of this study was to measure the prevalence of high frequency hearing loss consistent with noise exposure among sound technicians in Brazil and compare this with a control group without occupational noise exposure.
  
  
  METHODS
  This was a cross-sectional study comparing 177 participants in two groups: 82 sound technicians and 95 controls (non-sound technicians). A questionnaire on music listening habits and associated complaints was applied, and data were gathered regarding the professionals' numbers of working hours per day and both groups' hearing complaint and presence of tinnitus. The participants' ear canals were visually inspected using an otoscope. Hearing assessments were performed (tonal and speech audiometry) using a portable digital AD 229 E audiometer funded by FAPESP.
  
  
  RESULTS
  There was no statistically significant difference between the sound technicians and controls regarding age and gender. Thus, the study sample was homogenous and would be unlikely to lead to bias in the results. A statistically significant difference in hearing loss was observed between the groups: 50% among the sound technicians and 10.5% among the controls. The difference could be addressed to high sound levels.
  
  
  CONCLUSIONS
  The sound technicians presented a higher prevalence of high frequency hearing loss consistent with noise exposure than did the general population, although the possibility of residual confounding due to unmeasured factors such as socioeconomic status cannot be ruled out.
authors.affiliation: Urgency Medicine and Evidence-Based Medicine Department, Brazilian Cochrane Centre, Federal University of São Paulo, Brazil. re.lucci@terra.com.br
authors.forename: Regina P
authors.initials: RP
authors.lastname: El Dib
authors.forename: Edina M K
authors.initials: EM
authors.lastname: Silva
authors.forename: José F
authors.initials: JF
authors.lastname: Morais
authors.forename: Virgínia F M
authors.initials: VF
authors.lastname: Trevisani
mesh_terms: D000328:Adult; D000368:Aged; D001299:Audiometry; D001938:Brazil / Q000453:epidemiology; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006317:Hearing Loss, Noise-Induced / Q000139:chemically induced / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009146:Music; D009623:Noise, Occupational / Q000009:adverse effects*; D016273:Occupational Exposure / Q000009:adverse effects* / Q000706:statistics & numerical data; D015995:Prevalence; D011795:Surveys and Questionnaires