My immortal ear
With software "audacity" I can hear sound at 55 KHz . This is a very high frequency and I am 31 years old.

I am so sorry to disprove you franco, human ear cannot go after 20khz the same sound card is designed to produce 20khz, so you software is bullshitting you into believing that sound hardware can produce that frequency. The limit in frequency of EVERY sound card is 20khz , there is no need to go further, if you think you can hear 55khz, you'd better to take a trip at NASA and be inspected by their engeneers and medical staff.