title: The relationship between distortion product otoacoustic emissions and extended high-frequency audiometry in tinnitus patients. Part 1: normally hearing patients with unilateral tinnitus.
abstract: BACKGROUND
  The aim of this study was to evaluate distortion product otoacoustic emissions (DPOAEs) and extended high-frequency (EHF) thresholds in a control group and in patients with normal hearing sensitivity in the conventional frequency range and reporting unilateral tinnitus.
  
  
  METHODS
  Seventy patients were enrolled in the study: 47 patients with tinnitus in the left ear (Group 1) and 23 patients with tinnitus in the right ear (Group 2). The control group included 60 otologically normal subjects with no history of pathological tinnitus. Pure-tone thresholds were measured at all standard frequencies from 0.25 to 8 kHz, and at 10, 12.5, 14, and 16 kHz. The DPOAEs were measured in the frequency range from approximately 0.5 to 9 kHz using the primary tones presented at 65/55 dB SPL.
  
  
  RESULTS
  The left ears of patients in Group 1 had higher median hearing thresholds than those in the control subjects at all 4 EHFs, and lower mean DPOAE levels than those in the controls for almost all primary frequencies, but significantly lower only in the 2-kHz region. Median hearing thresholds in the right ears of patients in Group 2 were higher than those in the right ears of the control subjects in the EHF range at 12.5, 14, and 16 kHz. The mean DPOAE levels in the right ears were lower in patients from Group 2 than those in the controls for the majority of primary frequencies, but only reached statistical significance in the 8-kHz region.
  
  
  CONCLUSIONS
  Hearing thresholds in tinnitus ears with normal hearing sensitivity in the conventional range were higher in the EHF region than those in non-tinnitus control subjects, implying that cochlear damage in the basal region may result in the perception of tinnitus. In general, DPOAE levels in tinnitus ears were lower than those in ears of non-tinnitus subjects, suggesting that subclinical cochlear impairment in limited areas, which can be revealed by DPOAEs but not by conventional audiometry, may exist in tinnitus ears. For patients with tinnitus, DPOAE measures combined with behavioral EHF hearing thresholds may provide additional clinical information about the status of the peripheral hearing.
authors.affiliation: Institute of Physiology and Pathology of Hearing, Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Fabijańska
authors.forename: Jacek
authors.initials: J
authors.lastname: Smurzyński
authors.forename: Stavros
authors.initials: S
authors.lastname: Hatzopoulos
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Kochanek
authors.forename: Grażyna
authors.initials: G
authors.lastname: Bartnik
authors.forename: Danuta
authors.initials: D
authors.lastname: Raj-Koziak
authors.forename: Manuela
authors.initials: M
authors.lastname: Mazzoli
authors.forename: Piotr H
authors.initials: PH
authors.lastname: Skarżyński
authors.forename: Wieslaw W
authors.initials: WW
authors.lastname: Jędrzejczak
authors.forename: Agata
authors.initials: A
authors.lastname: Szkiełkowska
authors.forename: Henryk
authors.initials: H
authors.lastname: Skarżyński
mesh_terms: D000293:Adolescent; D000328:Adult; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold / Q000502:physiology; D016022:Case-Control Studies; D004423:Ear / Q000503:physiopathology; D005260:Female; D006309:Hearing / Q000502:physiology*; D006801:Humans; D008297:Male; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D014012:Tinnitus / Q000503:physiopathology*; D055815:Young Adult