title: Evaluation of distortion and transient evoked otoacoustic emission in tinnitus patients with normal hearing.
abstract: BACKGROUND
  Tinnitus is a perception of sound without external source. The exact etiology of tinnitus is not fully understood, although some researchers believe that the condition usually starts in the cochlea. The aim of this study was to determine the potential contribution of outer hair cell dysfunction to chronic tinnitus, by application of Distortion-Product Evoked Otoacoustic Emission (DPOAE) and Transient Evoked Otoacoustic Emission (TEOAE) and also to determine the relationship between tinnitus loudness and the amplitude of these two potentials.
  
  
  METHODS
  This study was conducted on 20 tinnitus patients aged 20-45 years and 20 age- and gender-matched control subjects. DPOAE and TEOAE were performed on each subject.
  
  
  RESULTS
  The difference in the amplitudes of TEOAE between the two groups was not significantly different (P=0.08), but the amplitude of DPOAE in patients with tinnitus was significantly lower than the corresponding value in the control subjects (P=0.01). There was no correlation between tinnitus loudness and the amplitudes of neither DPOAE nor TEOAE.
  
  
  CONCLUSIONS
  Abnormal findings in the DPOAE of tinnitus sufferers suggest some form of cochlear dysfunction in these patients. As there was no correlation between the amplitude of the recorded potentials and tinnitus loudness, factors other than cochlear dysfunction may also influence the loudness of tinnitus.
authors: Department of Audiology, Faculty of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran.
authors: Helnaz
authors: H
authors: Mokrian
authors: Department of Audiology, Faculty of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran.
authors: Abdolreza
authors: A
authors: Shaibanizadeh
authors: Department of Audiology, Faculty of Rehabilitation Sciences, Tehran University of Medical Sciences, Tehran, Iran.
authors: Saeid
authors: S
authors: Farahani
authors: Department of Statistics, Faculty of Rehabilitation Sciences, Tehran University of Medical Sciences, Tehran, Iran.
authors: Shohreh
authors: S
authors: Jalaie
authors: Department of Audiology, Faculty of Rehabilitation Sciences, Tehran University of Medical Sciences, Tehran, Iran.
authors: Parvane
authors: P
authors: Mahdi
authors: Department of Audiology, Faculty of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran.
authors: Amin
authors: A
authors: Amali
authors: Department of Audiology, Faculty of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran.
authors: Homa
authors: H
authors: Arian Nahad
keywords: Distortion-Product Evoked Otoacoustic Emissions; Normal hearing; Subjective Tinnitus; Transient Evoked Otoacoustic Emission