Medieval police sirens. Nothing quite so painful to the ear. The change in pitch comes from the doppler effect.
HIGH SPL WARNING:
Swinging cats can cause serious damage to ribbon microphones, eardrums, nearby upholstery, and the skin on your forearms. Do not combine cat swinging with alcohol, as serious injury or death could result. Cat swinging is not for everyone. Ask your doctor if you are healthy enough for feline activity before you start cat swinging. Some restrictions and limitations apply. See store for details.