title: Predicting hearing thresholds in occupational noise-induced hearing loss by auditory steady state responses.
abstract: OBJECTIVE
  Currently available behavioral tools for the assessment of noise-induced hearing loss (NIHL) depend on the reliable cooperation of the subject. Furthermore, in workers' compensation cases, there is considerable financial gain to be had from exaggerating symptoms, such that accurate assessment of true hearing threshold levels is essential. An alternative objective physiologic tool for assessing NIHL is the auditory steady state response (ASSR) test, which combines frequency specificity with a high level of auditory stimulation, making it applicable for the evaluation of subjects with a moderate to severe deficit. The primary aim of the study was to assess the value of the multifrequency ASSR test in predicting the behavioral warble-tone audiogram in a large sample of young subjects with NIHL of varying severity or with normal hearing. The secondary goal was to assess suprathreshold ASSR growth functions in these two groups.
  
  
  METHODS
  The study group included 157 subjects regularly exposed to high levels of occupational noise, who attended a university-associated audiological clinic for evaluation of NIHL from 2009 through 2011. All underwent a behavioral audiogram, and on the basis of the findings, were divided into those with NIHL (108 subjects, 216 ears) or normal hearing (49 subjects, 98 ears). The accuracy of the ASSR threshold estimations for frequencies of 500, 1000, 2000, and 4000 Hz was compared between groups, and the specificity and sensitivity of the ASSR test in differentiating ears with or without NIHL was calculated using receiver operating characteristic analysis. Linear regression analysis was used to formulate an equation to predict the behavioral warble-tone audiogram at each test frequency using ASSR thresholds. Multifrequency ASSR amplitude growth as a function of stimulus intensity was compared between the NIHL and normal-hearing groups for 1000 Hz and 4000 Hz carrier frequencies.
  
  
  RESULTS
  In the subjects with NIHL, ASSR thresholds to various frequencies were significantly and highly correlated with the behavioral warble-tone thresholds; Pearson correlation coefficients ranged from 0.6 to 0.8 over the four frequencies tested. Differences between thresholds ranged from 10 to 13 dB. The configuration of the ASSR waveforms closely approximated the behavioral audiogram. The sensitivity for screening hearing thresholds was 92%; by frequency, sensitivity ranged between 92.7 and 98.4%, but specificity was lower, especially at the low frequencies. ASSR accurately predicted moderate and severe NIHL. The mean ASSR growth amplitude to increasing stimulus level for 1000 and 4000 Hz was significantly steeper in the NIHL than in the normal-hearing group, with no significant difference between frequencies.
  
  
  CONCLUSIONS
  The ASSR test has a high sensitivity to detect moderate to severe hearing loss in subjects with NIHL. Its use can facilitate the early identification of noise-exposed workers with NIHL. It may also serve an important medico-legal function in cases of workers' compensation. The ASSR test is not, by itself, an appropriate tool for hearing screening in the general population.
authors: 1Department of Communication Sciences & Disorders, University of Haifa, Haifa, Israel; 2Institute for Audiology and Clinical Neurophysiology, Schneider Children's Medical Center of Israel, Petach Tikva, and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; and 3Department of Otolaryngology, Head and Neck Surgery, Rabin Medical Center, Petach Tikva, and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors: Joseph
authors: J
authors: Attias
authors: Hanin
authors: H
authors: Karawani
authors: Rafi
authors: R
authors: Shemesh
authors: Ben
authors: B
authors: Nageris
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001299:Audiometry / Q000379:methods; D001309:Auditory Threshold; D016022:Case-Control Studies; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D006317:Hearing Loss, Noise-Induced / Q000175:diagnosis* / Q000503:physiopathology; D006320:Hearing Tests / Q000379:methods; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000175:diagnosis* / Q000503:physiopathology; D012372:ROC Curve; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index