The temperature-dependent emission of low frequency sound by motile cultures of the ciliate Tetrahymena thermophilia.

When a sensitive condenser microphone is appropriately sealed and immersed into a motile suspension of Tetrahymena, a characteristic sound spectrum can be recorded. The spectrum of cells cultured at 25 degrees C and measured at 20 degrees contains three main components, centred around 40, 55 and 80 Hz. Both the intensity and distribution of the sound emission are altered when the cells are cooled to 12 degrees or warmed to 33 degrees C. No such sound emission is detectable from suspensions of sessile organisms.