Falls House Press - Vibrato Workbook, for flute players of all ages, with companion CD, by Dr. Chris Potter. This book provides a structure for intermediate level players of any age to develop and use vibrato. Vibrato is a tool that musicians use to add expression to their sound. You could think of it as controlled passion. Vibrato on the flute is a precise fluctuation in the speed of the air which causes slight changes in pitch and dynamics.