Vibrato is a musical effect consisting of a regular, pulsating change of pitch. It is used to add expression to vocal and instrumental music. Vibrato is typically characterised in terms of two factors: the amount of pitch variation (extent of vibrato) and the speed with which the pitch is varied (rate of vibrato).ibrato is typically characterised in terms of two factors: the amount of pitch variation (extent of vibrato) and the speed with which the pitch is varied (rate of vibrato).