Ultrasonic

Ultrasonic sound was sound at a frequency higher than human hearing. Other species could hear it, including Skarasens, (TV: Terror of the Zygons) Mandrels, (TV: Nightmare of Eden) Shrivenzales, (TV: The Ribos Operation) Gorrillazons, (COMIC: Carnage Zoo) the Apatosaurus-like creatures of Spekra (COMIC: Prisoners of Gritog) and the dinosaur-like creatures of Quorus. (PROSE: Doctor Who Fights Masterplan "Q")

Zarbi communicated by making ultrasonic sounds. The First Doctor, calling it an "extra-sonic" sound, claimed that it was a kind which young people and young animals could hear, explaining why only Vicki Pallister could hear it. (TV: The Web Planet)

During an attempt to obtain a Krikoosh from a zoo, the Daleks set off an ultrasonic signal that drove the animals berserk. (COMIC: Carnage Zoo)

The disintegrator gun used an ultrasonic beam to disintegrate the target. (TV: Day of the Daleks)

The TARDIS had ultrasonic showers. (PROSE: The Empire of Glass)