Appendix 1. Hearing related questionnaires

Hearing difficulty
 Choose the sentence that best describes your hearing 1. I feel difficulty in hearing2. I do not feel any difficulty in hearing
tinnitus
 Have you ever heard a sound in your ear within the past year? 1. Yes2. No3. I cannot remember
Noise exposure
 1. Have you worked for more than 3 months in a place with noise (such as mechanical or generator induced noise)? 2. Have you been exposed to loud noises for more than 5 hours a week other than occupational exposures? 3. So far, have you been exposed to sudden loud noises such as gunshots or explosions? 1. Yes (at least one)2. No3. I cannot remember