Audiometric data
Six-frequency PTA was performed before the start of treatment (D1) and on days 7 (early test point, D7), 13 (middle test point, D13), 24 (late test point, D24), and 90 (long-term test point, D90) or until the patient fully recovered. The mean PTA values at low-mid frequencies (0.25, 0.5, and 1 kHz) and high frequencies (2, 4, and 8 kHz) were calculated. The total effective rate was the sum of complete, marked and slight hearing gain (PTA >15 dBHL) according to Siegel’s criteria[3].