Your cat's ears can hear ultrasonic sounds.... Rodents use these sounds to communicate. Your cat can hear them but dogs and humans cannot. Your cat uses whiskers to gauge whether or not they can fit through an opening. Furthermore, your cat's collarbone does not connect to any other bones but instead sits buried in muscle. This makes it easier for your cat to squeeze through tight spots. Your cat purrs continuously... By flowing air past the voice box during both inhalation and exhalation.