This study discusses the structure of the calls of bush crickets Steropleurus nobrei and examines the way the structure of records of a bush-cricket call, comprising pure tone bursts and bursts of white noise, changes as these sounds propagate through different environments. Measurements of the coherence and spectral composition at different distances from the sound source are made in open and thickly vegetated environments. The results show that coherent frequency components in reproductions of the records of the natural call propagate over greater distances than do other components. The results are discussed in relation to the possible sources of information contained in insect calls and how the environment degrades these information sources as the call propagates away from the source. The consequences of the structure of the calls on the properties of the auditory organs of bush crickets is also discussed.

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