title: Extended frequency range hearing thresholds and otoacoustic emissions in acute acoustic trauma.
abstract: OBJECTIVE
  We sought to evaluate the relative value of pure tone audiometry (PTA), extended high-frequency audiometry (EFA) and transiently evoked otoacoustic emissions (OAE) and distortion products when monitoring acute acoustic trauma (AAT).
  
  
  METHODS
  Controlled prospective clinical study.
  
  
  METHODS
  Tertiary referral center.
  
  
  METHODS
  Seventy one active duty soldiers in the same age with normal hearing
  
  
  METHODS
  Forty one soldiers suffered assault-rifle-induced acute acoustic traumas with hearing loss and tinnitus. Thirty soldiers served as a control group.
  
  
  METHODS
  Pure tone threshold changes detected by PTA and EFA, amplitude and reproducibility changes in transiently evoked OAE, distortion products, and tinnitus analysis based on a visual analog scale.
  
  
  RESULTS
  Assault rifle-induced AAT caused unilateral temporary threshold shifts (TTS) in PTA and bilateral TTS in EFA. Two frequency regions with the largest threshold shifts were identified: one between 3 and 6 kHz and another between 11 and 14 kHz. The reproducibility of transiently evoked OAEs revealed changes related to the acoustic trauma in the 3- to 5-kHz frequency window. The amplitudes of the low stimulation level distortion products at 6 kHz were correlated with the audiometric AAT-induced TTS.
  
  
  CONCLUSIONS
  Acute acoustic trauma-induced audiometric TTS are predominantly confined to 2 specific frequency regions. PTA and EFA are both necessary to identify the full extent of acute acoustic trauma. PTA and EFA revealed that the TTSs were correlated to with distortion product OAE amplitude shifts at 6 kHz and changes in the reproducibility of transiently evoked OAE in the 3- to 5-kHz frequency window. PTA remains the most important measurement to monitor AAT. It may be useful to complement it with EFA, focusing on the 11 to 14 kHz frequency range. If used, OAE should be analyzed in the frequency range of 3 to 6 kHz.
authors.affiliation: Regional Military Medical Center, Military Medical Service, Swiss Armed Forces, Thun, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Büchler
authors.forename: Martin
authors.initials: M
authors.lastname: Kompis
authors.forename: Michel André
authors.initials: MA
authors.lastname: Hotz
mesh_terms: D000208:Acute Disease; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold / Q000502:physiology*; D003627:Data Interpretation, Statistical; D023381:Endpoint Determination; D005389:Firearms; D005500:Follow-Up Studies; D034381:Hearing Loss / Q000175:diagnosis / Q000209:etiology; D006316:Hearing Loss, High-Frequency / Q000175:diagnosis / Q000209:etiology; D006317:Hearing Loss, Noise-Induced / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008889:Military Personnel; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D013557:Switzerland; D014012:Tinnitus / Q000209:etiology; D055815:Young Adult