Fig. 8. Attenuation of pure-tone sound pulses (5-40 kHz) exceeding the spherical attenuation of 6 dB per double distance (`excess attenuation') at various distances. The attenuation was measured in a typical grassland habitat of the five Neoconocephalus species; the data shown here are taken from the best-fit curves for each frequency (see Materials and methods; Fig. 6).