The frequency of "ultra"sound is much much much higher than any frequency that any human being can hear.
Ultrasound frequencies in diagnostic radiology range from 2 MHz to approximately 15 MHz (although even higher frequencies may be used in some situations) ! That's a range from 100 times to 750 times the average limit of human hearing (20,000 Hz) ! (See more numbers below.)
Even when ultrasound blasts through your canal, shakes your tympanum, oscillates your ossicles, and attacks your hair cells, your brain never has a clue.
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Looking at it another way:
-- The exact upper and lower limits of human hearing are different for just about every individual on Earth. As a broad average for the whole human race, we commonly consider the range to be from 20 Hz to 20,000 Hz .
That's a range of almost exactly 10 octaves.
-- Ultrasound operating at 2 MHz is another 6.6 octaves above the upper audible frequency limit.
-- Ultrasound operating at 15 MHz is another 9.5 octaves above the upper audible frequency limit.