Changes

In general sounds that are '''produced with the mouth closed''', such as purrs, trills and chirrups, are '''distance-reducing signals'''. The same is true of vocalisations that are produced with the mouth initially open but closing whilst the sound is produced, such as the miaow. Strained intensity vocalisation that are '''made with the mouth open''' throughout the sound are generally '''distance increasing signals or signs of distress'''. This includes growls, hisses, spits, snarls and shrieks<ref>Kiley-Worthingon, M. (1984) Animal language? Vocal communication of some ungulates, canids and felids. ''Acta Zoologica Fennica''. 171, 83-88.</ref>.

In general sounds that are '''produced with the mouth closed''', such as purrs, trills and chirrups, are '''distance-reducing signals'''. The same is true of vocalisations that are produced with the mouth initially open but closing whilst the sound is produced, such as the miaow. Strained intensity vocalisation that are '''made with the mouth open''' throughout the sound are generally '''distance increasing signals or signs of distress'''. This includes growls, hisses, spits, snarls and shrieks<ref>Kiley-Worthingon, M. (1984) Animal language? Vocal communication of some ungulates, canids and felids. ''Acta Zoologica Fennica''. 171, 83-88.</ref>.

There is some evidence that cats are able to modify their vocalisations when communicating with people. In a study investigating human sensitivity to purring in cats, it was found that cats used a "solicitation purr" to obtain a response from people. This purr contains an embedded high pitched component that resembles sounds made by crying human infants, and which people experience as sounding urgent and disturbing<ref>McComb, K., Taylor, AM., Wilson, C., Charlton, BD. (2009) The cry embedded within the purr. "Cell Current Biology". 19(3), 507-508.</ref>.

There is some evidence that cats are able to modify their vocalisations when communicating with people. In a study investigating human sensitivity to purring in cats, it was found that cats used a "solicitation purr" to obtain a response from people. This purr contains an embedded high pitched component that resembles sounds made by crying human infants, and which people experience as sounding urgent and disturbing<ref>McComb, K., Taylor, A.M., Wilson, C., Charlton, B.D. (2009) The cry embedded within the purr. ''Cell Current Biology''. 19(3), 507-508.</ref>.

==Olfactory Communication==

==Olfactory Communication==