Objectives: We investigated cochlear function in normalhearing
patients with tinnitus using distortion product otoacoustic
Patients and Methods: The study included 20 normal-hearing
patients with tinnitus (13 males, 7 females; mean age 25
years; range 17 to 52 years) and 15 controls (10 males, 5
females; mean age 23 years; range 18 to 27 years) with normal
hearing. Both groups underwent routine audiological
tests including audiometry and tympanometry. Cubic
DPOAEs were recorded from both groups. Signal-to-noise
ratios (SNRs) lower than the 10th percentile of the control
values were regarded as abnormal or undetectable.
Results: Tinnitus was bilateral in seven patients and unilateral
in 13 patients. Seven patients with unilateral tinnitus and
all patients with bilateral tinnitus had a history of exposure to
noise. The mean perceived frequencies for tinnitus were 6.3
kHz and 6.2 kHz in the left and right ears, respectively.
Loudness was measured as 8 dB SL in the left ears, and 7
dB SL in the right ears. Compared to unilateral cases,
patients with bilateral tinnitus exhibited a higher percentage of
abnormal SNRs at most frequencies. Some asymptomatic
ears in the patient group had abnormal results.
Conclusion: These findings show that tinnitus in normalhearing
patients is often associated with varying degrees of
cochlear dysfunction. The results also suggest that tinnitus
may be regarded as an early manifestation of noise-induced
hearing loss in patients with a history of exposure to noise.
FREE FULL TEXTAnahtar Kelimeler: İşitme eşiği, fizyoloji; koklea/fizyopatoloji; uyarılmış potansiyeller, işitsel/fizyoloji; saç hücreleri, dış/fizyopatoloji; işitmekaybı, gürültüyle oluşan; otoakustik emisyonlar, spontan/fizyoloji;tinnitus/ tanı/ fizyopatoloji.