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Noises are difficult to describe, and this has been a barrier to understanding their meanings and using them in studies of behaviour. In the present study tape recordings and spectro‐graphic analysis were used to learn the properties of the noises and help to describe them. Noises fall into two groups, harsh noises and clear calls, which are considered seprately. Eight harsh noises associated with agonistic behaviour and four occurring in “friendly” situations are described. Clear calls show more individual variation and examples typical of five situations are given. A wide range of intermediates between the basic noises make a large “vocabulary” available to express small differences of mood.
Rowell et al. (1962) studied this question.