The normal range for young people is 20hz to 20khz, but high frequency perception declines as we age.
Use this flash based online hearing tests to see how sharp your hearing is.
Other hearing frequency facts:
Humans can hear between 20 Hz to 20,000 Hz
Dogs can hear between 40 Hz to 60,000 Hz
Bats can hear between 20 Hz to 120,000 Hz
Bats can hear between 1000 Hz to 90,000 Hz