I just tried the hearing test on this website: http://www.freemosquitoringtones.org/hearing_test/ The concept is that as our ears age, we lose the ability to hear higher frequencies. On the hearing test, I could only hear up to 10 KHz, even using the maximum volume setting on my Macbook. But on the home page, I see this information: 8khz - Everyone 10khz - 60 & Younger 12khz - 50 & Younger 14khz - 49 & Younger 15khz - 39 & Younger 16khz - 30 & Younger 17khz - 24 & Younger But I am only 31, and I can't even hear 12KHz. Am I going deaf? Should I go visit a doctor? I don't generally listen to loud music, and I very rarely wear headphones. Advice needed.