Infrasound: (Payne, et al. 1 9 86; Poole et a l. 1 988 :385,3 g6,39 1 ; PooIe 1994:332,347,344) Sound frequencies below the range of human-hearing (20-30 Hz); on a 10 hr sample of rumble-vocalizations at Amboseli, Kenya, only 27%o of the recorded calls were audible to the human observers Poole & Moss 1989:117). Some of these low ftequency calls are extremely powerful. Elephants are able to identify calling individuals up to 1.5 km away (McComb, et al. 2000), but infrasonic calls can probably be heard up to 5-10 Km away.