You may get more information / test tone from: http://www.audiocheck.net
Moreover, you may try to move your head or even go around the listening room. You may have a new experience about where the Perfect Listening Seat is. Actually, there is no such thing in the real world ... ... except you fix your head at one spot.
After the test, I found my hearing ability is not quite good ... I cannot hear the frequency start from 14,000 Hz.