1. A decibel (dB) is a logarithmic scale for sound. 1 decibel is the minimum intensity of sound that can be differentiated by the average human ear. Every 3 dB doubles the intensity of sound.
2. Just like pulse rate and bloop pressure is an average value fixed after comparing a large healthy population, so is the decibel. Therefore, just as you may have a pulse rate or blood pressure above or below the average 72/min and 120/80 mm of Hg respectively and still be considered normal, so is the case in hearing levels. There are some people with hearing better than the average and hence the PTA chart has a -10 dB above 0 dB.
3. Since your hearing thresholds are more than 10 dB in more than 3 successive frequencies, you have been declared unfit. There is no criteria in Armed Forces for 8000 Hz.
4. Though your hearing is nearly normal, this is a technical disqualification.
5. You may find it interesting to note that hearing loss
in the Armed Forces has been extensively studied and shown to occur 10 years earlier than in the general population due to exposure to firearm noise. Hence these rules are meant to protect you from further ear damage.