The Influence of High Frequency Hearing Loss on the Distortion Product Otoacoustic Emissions in Tinnitus Subjects with Normal Hearing Thresold (0,25-8kHz)

Aim of the study: To evaluate the influence of high frequency hearing loss (\u3e8000 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 HLfor 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