Klausner
Klausner is the story's protagonist. Having become obsessed with the idea that he is surrounded by sounds so high-pitched that they are inaudible to the human ear, Klausner invents a device that translates high vibrations in the air into tones he can hear through headphones. Dahl describes Klausner as being small and wiry and always moving his hands. He has pale white skin and grey eyes that peer out from thick lenses. It is unclear whether Klausner's obsession results from genius or his unstable mental and emotional state.
Mrs. Saunders
Mrs. Saunders is Klausner's neighbor. When she cuts roses to make a bouquet, Klausner's machine picks up on shrieking sounds Klausner believes are the roses crying out in pain. Mrs. Saunders humors Klausner's explanation while privately preparing herself to run inside to safety.
The Doctor
Dr. Scott is a doctor who periodically checks in on Klausner. The Doctor humors Klausner when he involves the Doctor in his experiments with the sound machine. Simultaneously, the Doctor is constantly assessing Klausner's behavior and looking for signs of madness.
