Can rabbits hear infrasonic and ultrasonic sounds? My bunny lifts up his ears when I take a step.
Rabbits can hear sounds down to 96 Hz; this is a lot higher than the lowest frequency humans can hear--about 20 Hz. This is above the range of infrasound: https://en.wikipedia.org/wiki/Infrasound
So rabbits cannot hear infrasound, but they can feel vibrations when you walk across the room.
Rabbits can hear sound up to 49 kHz, and this is in the range of ultrasonic sound. Ultrasonic sound is any frequency above 20 kHz and up to the radio frequency of 10 mHz and sometimes even higher for inspection of metall constructions.
So rabbits can hear ultrasound, or at least the lower part of the ultrasonic frequency band.