A fundamental aspect of good choral singing identified by performers, directors, critics and theorists is the concept of blend. Blend is a term that has essentially come to encompass all aspects of singing that lead to a sound in which no one voice is distinguishable from another. Directors and singers often identify vibrato as a key musical and vocal parameter affecting the blend of a group. Whilst being well analysed in solo singing, and particularly opera, vibrato has not yet been studied in chorus singing. This PhD project will use electrolaryngograph and acoustic data alongside synthesis experiments to analyse vibrato behaviour in individual singers when ‘blending’ their voices in a group. This will help to establish the extent to which vibrato is adapted in a group and to what extent this contributes to perceived choral blend.