**3.8 Prognosis factors for ISSHL improvement**

Based on the results of feature selection model, we identified the prognosis factors that affect ISSHL improvement by AT using a decision tree model. In patients who started AT within 2 weeks and over 6 months, the improvement was not affected by PTA on the day of the initial visit. Otherwise, in patients who started treatment 6 weeks - 6 months PTA on the day of the initial visit were found to be important variables to the prognosis for ISSHL improvement. Especially, in patients who started treatment between 2 and 6 weeks, pure tones at 500Hz (middle-low frequency range) were found to be important variables to the prognosis for ISSHL improvement (Fig. 3).
