Ultrasonic speaker for Arduino Mega

i curious if possible generate ultrasonic sounds arduino mega.  standard piezo buzzer reaches 10khz , need hit 50khz range, , upwards if possible.  have been told clock speed not fast enough generate such sounds.  if not true, there buzzer can use produce these sounds?

standard 40khz murata ultrasonic transducer.

quote

i have been told clock speed not fast enough generate such sounds.

who told that?

Arduino Forum > Using Arduino > Audio > Ultrasonic speaker for Arduino Mega

arduino