Test your hearing.
When you are young, you can hear sounds with frequencies up to 20 KHz. As you get older, the sensitivity of your ears becomes less for the higher frequencies.
If you are frequently subjected to loud noise, your hearing can deteriorate. Not only for high frequencies but also for specific frequencies in the mid or low range.
This application tests the sensitivity of your left and right ears for 20 frequencies between 100 Hz and 17KHz and compares the results.
Note: visit a doctor should you have any concerns about your hearing.