How old are you?
At 18 and older, the ranges start to fall from 18-20,000.
At 21, I'm hearing no more than 17,000 noticably, and without listening carefully
This is from Wiki:
"An infant's ear is able to perceive frequencies ranging from 16 Hz to 20,000 Hz; the average human can hear sounds between 20 Hz and 16,000 Hz."