2.4 Study design
Subjects were asked to complete the questionnaire by themselves. If they could not do so, a staff or a questionnaire administrator would help them. The HDRS test was administered in a face to face interview. Following the procedures, the audiometric assessment was performed. The audiological evaluation consisted of pure-tone octave air conduction audiometry and speech audiometry including speech discrimination scores in quiet condition. The pure tone average (PTA) air-conduction threshold was calculated as the average pure-tone threshold at 500, 1 and 2 kHz in each ear. All PTAs in the better hearing ear were used as criteria.