[The influence of high frequency hearing loss on the distortion product otoacoustic emissions in tinnitus subjects with normal hearing threshold (0,25-8 kHz)].

AIM OF THE STUDY To evaluate the influence of high frequency hearing loss (> 8000 Hz) on distortion product otoacoustic emissions registered in the frequency range from 0,5 to 8 kHz. MATERIAL AND METHODS 280 ears with tinnitus and normal hearing (0.25-8 kHz) divided into 3 groups depending on the degree of high frequency hearing loss: group A--hearing threshold up to 20 dB for 10, 12.5, 14 and 16 kHz (68 ears); group B--hearing threshold 25-40 dB HL for at least one of four EHfs (93 ears); group C--hearing threshold above 40 dB HL for at least one of four EHFs (119 ears). For each group mean audiogram and DP-gram were obtained and statistical analysis was used for comparison across these groups. RESULTS Mean DPOAE values in group C were significantly lower in comparison with group A for the frequency range 2-8 kHz, and in comparison with group B were significantly lower for the frequency range 4-8 kHz. CONCLUSIONS High frequency hearing loss (above 8 kHz) has a relevant influence on distortion product otoacoustic emissions registered at frequencies below 8 kHz in tinnitus patients. The greater is hearing loss above 8 kHz, the lower is DPOAE value below 8 kHz.