A highly variable class or type of tonal vocalisations that is characterised by calls with very low fundamental frequencies. Rumbles are the most frequently heard call type in the repertoire of all age/sex classes of African savannah elephants and are easily distinguished from other types by their very low frequencies and clear harmonic structure. Fundamental frequencies range from 8-34 Hz depending upon the callers age, body size, arousal level and call context.
Some rumbles are highly modulated, powerful sounds; others rise or fall in pitch; some rumble contours are flat, some undulating, and still others are jittery. Rumbles range in duration from less than half a second to almost 12 seconds and may be emitted as a soft fluttering whisper or an explosive throaty resonance with sound pressure levels up to 103 dB extrapolated to 5 m from source.
References: Douglas-Hamilton 1972: ch 6 [Growl]; Berg 1983 [Growl]; Payne et al 1986; Leong et al 2003; Poole et al 1988; Stoeger-Horwath et al 2007; Poole 2011. (Full reference list)
This behavior occurs in the following context(s): Advertisement & Attraction, Aggressive, Ambivalent, Attacking & Mobbing, Attentive, Avoidance, Birth, Calf Nourishment & Weaning, Calf Reassurance & Protection, Coalition Building, Conflict & Confrontation, Courtship, Movement, Space & Leadership, Social Play, Submissive, Vigilance, Protest & Distress