title: High-frequency hearing thresholds: effects of age, occupational ultrasound and noise exposure.
abstract: OBJECTIVE
  It has been suggested that high-frequency audiometry (HFA) could represent a useful preventive measure in exposed workers. The aim was to investigate the effects of age, ultrasound and noise on high-frequency hearing thresholds.
  
  
  METHODS
  We tested 24 industrial ultrasound-exposed subjects, 113 industrial noise-exposed subjects and 148 non-exposed subjects. Each subject was tested with both conventional-frequency (0.125-8 kHz) and high-frequency (9-18 kHz) audiometry.
  
  
  RESULTS
  The hearing threshold at high frequency deteriorated as a function of age, especially in subjects more than 30 years old. The ultrasound-exposed subjects had significantly higher hearing thresholds than the non-exposed ones at the high frequencies, being greatest from 10 to 14 kHz. This hearing loss was already significantly evident in subjects with exposure <5 years and increased with years of exposure and advancing age. The noise exposure group had significantly higher hearing thresholds than the non-exposed group at the conventional frequencies 4 and 6 kHz and at the high frequency of 14 kHz. After stratification for age, there was a significant difference between the two groups at 9-10 and 14-15 kHz only for those under 30 years of age.
  
  
  CONCLUSIONS
  Multivariate analysis indicated that age was the primary predictor, and noise and ultrasound exposure the secondary predictors of hearing thresholds in the high-frequency range. The results suggest that HFA could be useful in the early diagnosis of noise-induced hearing loss in younger groups of workers (under 30 years of age).
authors.affiliation: University Hospital of Padua, Padua, Italy, isabella.macca@unipd.it.
authors.forename: Isabella
authors.initials: I
authors.lastname: Maccà
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Scapellato
authors.forename: Mariella
authors.initials: M
authors.lastname: Carrieri
authors.forename: Stefano
authors.initials: S
authors.lastname: Maso
authors.forename: Andrea
authors.initials: A
authors.lastname: Trevisan
authors.forename: Giovanni Battista
authors.initials: GB
authors.lastname: Bartolucci
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000367:Age Factors; D000368:Aged; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold; D005260:Female; D006317:Hearing Loss, Noise-Induced / Q000175:diagnosis / Q000453:epidemiology*; D006801:Humans; D007221:Industry; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009623:Noise, Occupational / Q000009:adverse effects*; D009784:Occupational Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D012307:Risk Factors; D012907:Smoking; D055815:Young Adult